ELECTRIC ACTUATOR AND ELECTRIC MOBILITY

An electric actuator includes an electric motor, a drive device that drives the electric motor to output a first rotary motion using power accumulated in a capacitor, and a motion converter that is coupled to the electric motor and converts the first rotary motion into a second rotary motion. The first rotary motion is forward and reverse rotary motions that are output by the electric motor as the drive device drives the electric motor to repeat forward rotation and reverse rotation. The second rotary motion is a unidirectional rotary motion. Regenerative electric power generated in the electric motor by the electric motor repeating the forward rotation and the reverse rotation is supplied to the capacitor.

BACKGROUND

Technical Field

The present disclosure relates to electric actuators and electric mobility vehicles provided with the electric actuators.

Related Art

Industrial machinery and electric vehicles in which electric actuators such as motors are used as drive sources are widely used. Power saving of drive sources is strongly required to realize energy saving in society.

SUMMARY

A conventional electric car only provides regenerative electric power generation by a motor generator during inertial driving and braking, and there is room for improvement.

Aspects of the present disclosure are advantageous to provide an electric actuator with improved power-saving performance.

According to aspects of the present disclosure, there is provided an electric actuator including an electric motor, a drive device that drives the electric motor to output a first rotary motion using power accumulated in a capacitor, and a motion converter that is coupled to the electric motor and converts the first rotary motion into a second rotary motion. The first rotary motion is forward and reverse rotary motions that are output by the electric motor as the drive device drives the electric motor to repeat forward rotation and reverse rotation. The second rotary motion is a unidirectional rotary motion. Regenerative electric power generated in the electric motor by the electric motor repeating the forward rotation and the reverse rotation is supplied to the capacitor.

DETAILED DESCRIPTION

It is noted that various connections are set forth between elements in the following description. It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. Aspects of the present disclosure may be implemented on circuits (such as application specific integrated circuits) or in computer software as programs storable on computer-readable media including but not limited to RAMs, ROMs, flash memories, EEPROMs, CD-media, DVD-media, temporary storage, hard disk drives, floppy drives, permanent storage, and the like.

The inventor has discovered that efficiency of regenerative electric power utilization can be increased by reversing drive of an electric motor at a high repetition frequency. The high repetition frequency is, for example, 10 Hz or higher, but is not limited to 10 Hz or higher.

Illustrative embodiments of the present disclosure will be described below with reference to the drawings. In the following description, identical or corresponding items will be marked with identical or corresponding reference numerals, and redundant explanations will be omitted. In addition, in each figure, when multiple items with a common reference numeral are indicated, the reference numeral is not necessarily marked to all of those multiple items and the indication of the reference numeral to some of those multiple items is omitted as appropriate.

First Embodiment

FIGS.1and2are a perspective view and a plan view, respectively, of an electric actuator100according to a first embodiment of the present disclosure. InFIG.2, a portion of a piston50, which will be described later, is shown in cross-sectional view.

As shown inFIG.1, the electric actuator100includes a drive unit100dand a crankshaft70. The electric actuator100may further include a servo amplifier95(drive device) and a controller96which are described below with reference toFIGS.5and6.

In this specification, the term electric actuator may mean only a motor and a mechanism driven by the motor, may mean a set of a motor and a mechanism (referred to as a mechanism part) plus a drive device that drives the motor, or may mean to further include a controller that controls the drive device. When the electric actuator includes the drive device and the controller, the drive device and the controller may be installed in the same housing as the mechanism part, or may be configured as a device separate from the mechanism part and connected to the mechanism part by a cable or the like.

The drive unit100dincludes a motor10(electric motor), a bearing30, a ball screw40(feed screw mechanism), linear motion part50(hereinafter referred to as “piston50”), and a connecting rod60.

The motor10is, for example, an ultra-low inertia and high output type AC servomotor. The use of such ultra-low inertia and high output type motor10enables to drive the motor10to rotate back and forth at high frequencies of, for example, 100 Hz or higher.

A screw shaft41of the ball screw40is rotatably supported by the bearing30fixed to a frame (not shown). The screw shaft41is connected to a shaft11of the motor10by a shaft coupling20.

The piston50is a cylindrical member to which a hollow portion50aextending in the direction of an axis line Ax1is formed. The axis line Ax1is a center line of the drive unit100dand is a straight line common to axes of rotation of the motor10and the ball screw40. A nut42of the ball screw40is for example housed in one end portion of the hollow portion50aof the piston50(left end portion inFIG.2) and is fixed to the piston50.

At the other end portion of the piston50(right end inFIG.2), a pin52is attached perpendicular to an axis of the piston50(in other words, parallel to the crankshaft70).

FIG.3is a side view of the connecting rod60. The connecting rod60has a small end part62to which a small diameter pin hole62ais formed, a large end part64to which a large diameter pin hole64ais formed, and a rod part66connecting the small end part62and the large end part64. The pin holes62aand64aare formed parallel to each other.

The pin52is inserted into the pin hole62aof the small end part62, for example via a bush (not shown). Both ends of the pin52are inserted into a pair of pin holes50b(FIG.2) formed to the other end portion of the piston50and fixed to the piston50. As a result, the connecting rod60is connected to the other end portion of the piston50via the pin52at the small end part62to be rotatable within a certain angular range with the pin52as the central axis of rotation. In addition to the pin52(first pin), the connecting rod60is rotatably connected to a crank pin72(second pin) which will be described later.

FIG.4shows a side view of the crankshaft70. The crankshaft70has a pair of crank journals71coaxially disposed (i.e., axes of rotation or centerlines are coincident), a crank pin72disposed eccentrically with respect to axis lines of the crank journals71(i.e., axis Ax2which is an axis of rotation of the crankshaft70), a pair of crank arms73connecting the crank journals71and the crank pin72, a pair of balance weights74disposed on opposite sides of respective crank arms73with respect to the axis line Ax2, and an output shaft75coaxially coupled to one of the crank journals71. The balance weights74are formed to counteract imbalances created by the crank pin72and the crank arms73, which are eccentric with respect to the axis line Ax2.

The crankshaft70is a rotating body rotatably supported at the pair of crank journals71by a not-shown pair of bearings (e.g., rolling bearings) fixed to the frame (not shown).

The crank pin72is an eccentric pin eccentric with respect to the axis of rotation of the crankshaft70and is inserted into the pin hole64aof the large end part64of the connecting rod60, for example, via a bush (not shown). The crankshaft70is thus rotatably connected to the connecting rod60.

For example, oilless bushes are used as the bushes that engage with the pin holes62aand64aof the connecting rod60. Other types of bearings, such as rolling bearings, may be used in place of the bushes.

The motor10is driven so that the shaft11repeatedly rotates back and forth within a predetermined angular range. In other words, the motor10repeats forward and reverse rotations at a predetermined frequency. The rotation of the motor10(more specifically, the reciprocating rotary motion, i.e., forward and reverse rotary motions) is converted into linear motion by the ball screw40and transmitted to the piston50. As a result, the piston50, together with the nut42of the ball screw40, moves in a reciprocating linear motion on the axis line Ax1with a predetermined stroke. In other words, the ball screw40functions as a first motion converter that converts the reciprocating rotary motion (the forward and reverse rotary motions) of the motor10into a reciprocating linear motion. The reciprocating linear motion of the piston50in the direction of the axis line Ax1is transmitted by the connecting rod60to the eccentric crank pin72of the crankshaft70and converted into rotary motion of the crankshaft70. That is, the connecting rod60and the crankshaft70(as well as the pin52rotatably supporting the connecting rod60and the not-shown bearings rotatably supporting the crankshaft70) configures a crank mechanism (more specifically, a slider crank mechanism) as a second motion converter that converts the reciprocating motion (reciprocating linear motion) into a unidirectional rotary motion (hereinafter referred to as “unidirectional rotary motion”).

FIG.5is a block diagram showing a schematic configuration of an electric power feeding system90S (electric drive system90) that supplies driving electric power to the motor10.FIG.6is a diagram showing a circuit configuration of an electric drive system90. The electric power feeding system90S constitutes the electric drive system90together with the motor10.

A primary power source91is a commercial power source or electric power supply device, which provides, for example, three-phase alternating current electric power. The electric power supplied from the primary power source91(hereinafter referred to as “system electric power”) is supplied to a servo amplifier95(drive device) via a circuit breaker92, an electromagnetic switch93, and a reactor94. The servo amplifier95is an inverter device that converts the alternating current supplied from the primary power source91into driving electric power for the motor10, and supplies the electric power supplied from the primary power source91to the motor10. The motor10is connected to an output terminal of the servo amplifier95, and the drive electric power is supplied from the servo amplifier95to the motor10. The servo amplifier95is communicatively connected to a controller96and operates in accordance with control by the controller96.

The servo amplifier95includes a power regenerative converter95a, an inverter95b, and a capacitor95c. The power regenerative converter95ais a converter suitable for electric power regeneration and is, for example, a PWM (Pulse Width Modulation) converter that sinusoidalizes electric power supply side current by PWM control. The power regenerative converter95amay also be a converter that performs electric power conversion using the 120-degree-energization method. The inverter95bis, for example, a PWM inverter that controls the output electric power by PWM control. The power regenerative converter95aof the present embodiment has both a function of rectifying the alternating current supplied from the primary power source91during power operation (i.e., an operation mode in which the motor10is driven by the electric power supplied from the servo amplifier95) and a function of generating alternating current of the same quality as the system electric power to be returned to the primary power source91during regenerative operation. However, a converter dedicated to electric power operation and a converter dedicated to electric power regeneration may be provided separately.

The power regenerative converter95aincludes switching elements SW1to SW14, a capacitor (or condenser) C, and a transformer Tr. The inverter95bincludes switching elements SW15to SW20. The switching elements SW1to SW20are, for example, IGBTs (Metal Oxide Semiconductor Field Effect Transistors).

When the electric power supplied from the primary power source91(e.g., single-phase three-wire commercial power source or three-phase three-wire commercial power source) is supplied to the motor10, the switching elements SW1to SW6are repeatedly turned on and off by the controller96in accordance with a frequency of the alternating current electric power supplied from the primary power source91to rectify the alternating current electric power supplied from the primary power source91.

When the electric power supplied from the primary power source91is supplied to the motor10, the electric power rectified by the switching elements SW1to SW6is smoothed by the capacitor C.

When the electric power supplied from the primary power source91is supplied to the motor10, the switching elements SW7and SW10and the switching elements SW8and SW9are alternately and repeatedly turned on and off by the controller96so that the electric power smoothed by the capacitor C is transmitted from the primary coil L1to the secondary coil L2of the transformer Tr.

When the electric power supplied from the primary power source91is supplied to the motor10, the switching elements SW11and SW14and the switching elements SW12and SW13are alternately and repeatedly turned on and off by the controller96to rectify the electric power transmitted from the primary coil L1to the secondary coil L2.

When the electric power supplied from the primary power source91is supplied to the motor10, the electric power rectified by the switching elements SW11to SW14is smoothed by the capacitor95c.

When the electric power supplied from the primary power source91is supplied to the motor10, the switching elements SW15to SW20are repeatedly turned on and off by the controller96, so that the electric power smoothed by the capacitor95cis converted into alternating current electric power with phase differences of 120 degrees and supplied to the motor10and supplied to the motor10.

When the regenerated electric power from the motor10is supplied to the servo amplifier95, the alternating current electric powers supplied from the three phases of the motor10, respectively, are rectified by diodes connected in parallel with the switching elements SW15to SW20, respectively.

When the regenerated electric power from the motor10is supplied to the servo amplifier95, the electric power rectified by the diodes connected in parallel with the switching elements SW15to SW20, respectively, is smoothed by the capacitor95c.

When the regenerated electric power from the motor10is supplied to servo amplifier95, switching elements SW11and SW14and the switching elements SW12and SW13are alternately and repeatedly turned on and off by the controller96, so that the electric power smoothed by the capacitor95cis transmitted from the secondary coil L2to the primary coil L1of the transformer Tr.

When the regenerated electric power from the motor10is supplied to the servo amplifier95, the electric power transmitted from the secondary coil L2to the primary coil L1is rectified by diodes connected in parallel with the switching elements SW7to SW10, respectively.

When the regenerated electric power from the motor10is supplied to the servo amplifier95, the electric power rectified by the diodes connected in parallel with the switching elements SW7to SW10, respectively, is smoothed by the capacitor C.

When the regenerated electric power from the motor10is supplied to the servo amplifier95, the switching elements SW1to SW6are repeatedly turned on and off by the controller96, so that the electric power smoothed by the capacitor C is converted into alternating current electric power and supplied to the primary power source91.

When driving the motor10(during power operation), the alternating current electric power output from the reactor94is converted into direct current by the power regenerative converter95a, smoothed by the capacitor95c, and then converted into alternating current (e.g., pulse train) driving electric power by the inverter95b. The driving electric power output from the inverter95bis input to the motor10to drive the motor10to rotate.

When the motor10generates regenerative electric power (during regenerative operation), the regenerative electric power output from the motor10is converted into direct current by the inverter95band input to the power regenerative converter95avia a direct current bus bar95d. One system of the direct current bus bar95dconsists of a pair of positive and negative conductive wires. The power regenerative converter95aconverts the direct current electric power supplied from the direct current bus bar95dto sinusoidal alternating current and outputs the alternating current to the primary power source via the reactor94, the electromagnetic switch93, and the circuit breaker92.

FIG.7Ais a graph showing a drive waveform of one cycle of the motor10.FIG.7Bis a simplified graph showing a change in the rotation speed [rpm] of the motor10in the first half of one cycle of the motor10, andFIG.7Cis a simplified graph showing the change in the rotation speed of the motor10in the second half of one cycle of the motor10.FIG.7Dis a simplified graph showing a change in torque [Nm] of the motor10in the first half of one cycle of the motor10, andFIG.7Eis a simplified graph showing the change in torque of the motor10in the second half of one cycle of the motor10. InFIG.7A, the horizontal axis represents time t, and the vertical axis represents an angular position0of the shaft11. InFIGS.7B and7C, the horizontal axis represents time t, and the vertical axis represents the rotation speed of motor10. InFIGS.7D and7E, the horizontal axis represents time t, and the vertical axis represents torque of motor10. The respective time widths inFIGS.7A through7Ecoincide with each other.

The motor10is driven so that the angular position0of the shaft11fluctuates repeatedly in the range of −θa to θa in accordance with a sinusoidal drive waveform during the repeated passage of time t from time t0to time t6. The drive waveform of the motor10is not limited to a sine wave. When the drive waveform of the motor10is a sinusoidal drive waveform, an actual waveform of a rotation speed (the rotation speed) of the motor is a cosine waveform. However, inFIGS.7B and7C, for convenience of explanation, the waveform of the rotation speed of the motor is shown in a simplified form, with constant speed change for a range with large changes and no speed change (constant rotation speed) for a range with small changes.

In section A shown inFIG.7A, or more precisely, for example, in the first period from time t0to time t1, the shaft11is accelerated in the positive rotation direction. In other words, in the first period, the rotation speed of the motor10in forward rotation direction increases, and torque generated at this time is defined as a positive torque (acceleration torque). Also, at this time, electric power is supplied from the servo amplifier95to the motor10(power operation). For example, in the first period, electric power accumulated in the capacitor95cand the capacitor C is supplied to the motor10, and shortfall of electric power is supplied to motor10from the primary power source91.

In section B shown inFIG.7A, or more precisely, for example, in the second period from time t2to time t3, the shaft11is decelerated in the positive rotation direction. In other words, in the second period, the rotation speed of the motor10in the forward rotation direction decreases, and negative torque (deceleration torque) is generated. At this time, regenerative electric power is supplied from the motor10to the servo amplifier95(regeneration). For example, in the second period, the regenerated electric power from the motor10is accumulated in the capacitor95cand the capacitor C.

In section C shown inFIG.7A, or more precisely, for example, in the third period from time t3to time t4, the shaft11is accelerated in the negative rotational direction. In other words, in the third period, the rotation speed of the motor10in the reverse rotation direction increases, and torque generated at this time is defined as a positive torque (acceleration torque). Also, at this time, electric power is supplied from the servo amplifier95to the motor10(power operation). For example, in the third period, the electric power accumulated in the capacitor95cand the capacitor C is supplied to the motor10, and shortfall of electric power is supplied to the motor10from the primary power source91.

In section D shown inFIG.7A, or more precisely, for example, in the fourth period from time t5to time t6, the shaft11is decelerated in the negative rotation direction. In other words, in the fourth period, the rotation speed of the motor10in the reverse rotation direction decreases, and negative torque (deceleration torque) is generated. At this time, regenerative electric power is supplied from the motor10to the servo amplifier95(regenerative operation). For example, in the fourth period, the regenerated electric power from the motor10is accumulated in the capacitor95cand the capacitor C.

In this way, the power operation and regeneration are repeated, and the electric power accumulated in the capacitor95cand the capacitor C during regeneration can be used to drive the motor10in the next power operation, thus reducing the electric power supplied from the primary power source91to the motor10in the next power operation. This allows to make the electric drive system90more power-efficient. Furthermore, the shaft11of the motor10rotates back and forth by repeating acceleration (power operation) and deceleration (regenerative operation) while alternating the direction. Such reciprocating rotation is repeated at, for example, a repetition frequency of 500 Hz at maximum.

As described above, in the present embodiment, the supply of electric power to the motor10and the generation of regenerative electric power by the motor10are alternately repeated in order to make the motor10perform repeating acceleration and deceleration operations. Short-time (e.g., about one cycle of the motor10) voltage fluctuations in the direct current bus bar95dcaused by the transfer of electric power to and from the motor10are adjusted (in other words, leveled) mainly by the capacitor95c. Therefore, most of the electric power supplied to the motor10in sections A and C is recovered and reused as regenerative electric power in sections B and D, allowing the motor10to be driven with almost no consumption of electric power supplied from the primary power source91.

Table 1 shows driving conditions and measurement results of electric power consumption of the electric actuator100of the present embodiment.

“Frequency F” is the number of times per second that one cycle of driving shown inFIGS.7A to7Eis repeated. Electric power consumption was measured by varying the frequency F at 25 Hz intervals up to a maximum of 200 Hz. However, the minimum frequency was set not at 0 Hz but at 10 Hz, which allows stable operation.

“Torque To” is a maximum value (amplitude) of a relative torque (expressed as a percentage against a rated torque) of the shaft11of the motor10.

The “Power Consumption Value WA” is an average value of electric power consumption of the electric drive system90as a whole, as measured by a power meter PM upstream of the circuit breaker92(FIG.5).

“Output Power WB” is an average value of electric power output from the servo amplifier95to the motor10.

“Energy Saving Rate R” is a ratio of electric power consumption reduced by the reuse of regenerative electric power and is calculated by R=100×(1−WA/WB).

By using the electric actuator100of the present embodiment, the energy saving rate of over 70% is achieved at the frequencies F below 200 Hz. In particular, the energy saving rate exceeding 90% is achieved in a low frequency range below 75 Hz.

The electric power consumption reduction effect in by the electric actuator100of the present embodiment can be obtained even when the repetition frequency of the reciprocating rotation of the motor10is set at 1 Hz, but when the repetition frequency is set at 3 Hz or higher (more preferably 5 Hz or higher), the regenerative electric power is efficiently reused by the electric actuator100itself, resulting in good energy saving rate.

FIG.8Ais a graph schematically showing a drive waveform of a typical conventional motor, andFIG.8Bis a graph schematically showing a drive waveform of the motor10of the present embodiment.

As shown inFIG.8A, in the driving of the typical conventional motor, the motor is accelerated to a predetermined rotation speed in section T1and is then continuously driven at a constant speed (section T2), and is then decelerated to a stop at the end (section T3). In such driving, regenerative electric power is generated only in section T3. Therefore, the electric power consumption reduction effect through the use of regenerative electric power is modest.

On the other hand, in the present embodiment, as shown inFIG.8B, acceleration (power operation) and deceleration (regenerative operation) of the motor10are repeated at a high frequency over the entire section from the start to the end of driving. The regenerative electric power generated during deceleration is immediately consumed in the next power operation. That is, the generation and consumption of the regenerative electric power are routinely repeated from the start to the end of driving. As a result, in the present embodiment, the electric power consumption reduction effect by the use of the regenerative electric power is extremely significant.

As described above, with the electric actuator100according to the present embodiment, the motor10can output unidirectional rotary motion while actively generating regenerative energy by rotating the motor10forward and in reverse due to a motion converter that converts the forward and reverse rotary motions output by the motor10into unidirectional rotary motion. Therefore, the unidirectional rotary motion used for mobility vehicles such as automobiles and trains can be obtained with less electric power consumption than when the unidirectional rotary motion is obtained directly from the shaft of the motor10.

Second Embodiment

FIGS.9A and9Bare diagrams illustrating innovations in control of an electric actuator according to the present embodiment.FIG.9Ashows an example of control in the electric actuator100according to the first embodiment, andFIG.9Bshows an example of control of the electric actuator according to the present embodiment.

The vertical axes inFIGS.9A and9Bshow position of the piston50in reciprocating linear motion. Positions100and −100indicate the positions of the piston50when the slider crank mechanism of the electric actuator is at the bottom dead point and top dead point, respectively.

The horizontal axes inFIGS.9A and9Bshow phase of the crankshaft70in unidirectional rotary motion. The phases90and270show the phases of the crankshaft70when the slider crank mechanism of the electric actuator is at the bottom dead point and top dead point, respectively.

A configuration of the electric actuator according to the present embodiment is identical to the configuration of the electric actuator100of the first embodiment, except that the controller96is configured to be able to perform control of the motor10described below (phase shift control). Therefore, in the electric actuator according to the present embodiment, the reciprocating rotary motion of the motor10is also converted into a reciprocating linear motion by the ball screw40, and the reciprocating linear motion is further converted into and output as a unidirectional rotary motion by the slider crank mechanism. The sinusoidal waveforms inFIGS.9A and9Bshow a relationship between the position of the piston50and the phase of the crankshaft70in these electric actuators.

In the electric actuator100according to the first embodiment, as shown inFIG.9A, the controller96Servo amplifier95is controlled so that the direction of rotation of the motor10is switched from forward to reverse at timing t1when the piston50reaches the bottom dead point, and so that the direction of rotation of motor10is switched from reverse to forward at timing t2when the piston50reaches the top dead point. This allows the reciprocating linear motion to be converted into the rotary motion while maintaining the direction of rotation of the crankshaft70due to inertia at the dead points (top dead point and bottom dead point) where no rotational force is generated on the crankshaft70by the movement of the piston50. In other words, the reciprocating linear motion can be converted into unidirectional rotary motion.

When switching between forward and reverse rotations of the motor10, a large torque is generated in the motor10. Therefore, if the direction of rotation is switched at the top dead point and bottom dead point, where the force transmitted from the piston50to the crankshaft70does not act in the tangential direction (rotational direction) but only in the radial direction, a large force in the radial direction of the crankshaft70is generated due to the large torque generated by the motor10. As a result, vibration occurs in the crankshaft70, which may inhibit smooth rotation of the crankshaft70.

Taking these circumstances into consideration, in the electric actuator of the present embodiment, the controller96controls the servo amplifier95to switch the rotation of the motor10between forward and reverse rotations while avoiding timing t1when the piston50reaches the bottom dead point and timing t3when it reaches the top dead point. For example, as shown inFIG.9B, the controller96may control the servo amplifier95to switch the direction of rotation from forward to reverse at timing t3, which is slightly later than timing t1when the piston50reaches its bottom dead point, and to switch the direction of rotation from reverse to forward at timing t4, which is slightly later than timing t2when the piston50reaches the top dead point. The time difference (t3−t1, t4−t2) corresponds, for example, to about 0.5 degrees of the phase of the crankshaft70, and displacement that occurs during this time difference is generally within a backlash (joint gap) of the crank mechanism. The above time difference (t3−t1, t4−t2) can be set to 1.5 degrees or less of the phase of the crankshaft70, and preferably 1 degree or less. Furthermore, it is more desirable that the above time difference (t3−t1, t4−t2) is set to 0.5 degrees or less.

As described above, by controlling the motor10to switch the direction of rotation at the positions off from the top dead point and the bottom dead point, it is possible to apply rotational force at the top dead point and the bottom dead point while suppressing the force acting in the radial direction of the crankshaft70. Therefore, the electric actuator according to the present embodiment can output smooth unidirectional rotation while suppressing vibration more than the electric actuator100according to the first embodiment.

Specific control methods include a method of providing a constant phase difference in phase of the control of the motor10relative to the phase of the crankshaft70over the entire control section, and a method of gradually increasing and decreasing (eliminating) the phase difference in the vicinity of the dead points (upper and lower dead points) (e.g., within +10° of the dead points).

AlthoughFIG.9Bshows an example of switching the direction of rotation after passing through the top and bottom dead points, the controller96may control the servo amplifier95to switch the direction of rotation before passing through the top and bottom dead points.

Third Embodiment

FIGS.10A and10Bare diagrams illustrating innovations in the control of the electric actuator according to the present embodiment.FIG.10Ais a diagram showing the relationship between the position of the piston50and the phase of the crankshaft70in the electric actuator according to the present embodiment, andFIG.10Bis a diagram showing a relationship between torque limitation and the phase of the crankshaft70in the electric actuator according to the present embodiment.

A configuration of the electric actuator according to the present embodiment is identical to the configuration of the electric actuator100of the first embodiment, except that the controller96is configured to be able to perform control of the motor10described below (load suppression control).

As described above in the second embodiment, when the direction of rotation of the motor10is switched at the top dead point and the bottom dead point, a large force acts on the crankshaft70in the radial direction, and vibration is likely to occur on the crankshaft70. Therefore, in the present embodiment, the controller96controls the servo amplifier95so that torque of the motor10is limited at least at the timings of reaching the dead points (the top dead point and the bottom dead point). For example, as shown inFIGS.10A and10B, the controller96may limit the torque of the motor10near the upper and lower dead points (θ1to θ2and θ3to θ4) where the direction of rotation switches, and may control the motor10within the limited torque range. This prevents excessive force from being applied to the crankshaft70in the radial direction, thereby suppressing the occurrence of vibrations that inhibit smooth rotation of the crankshaft70. Therefore, the electric actuator according to the present embodiment can output smooth unidirectional rotation while suppressing vibration more than the electric actuator100according to the first embodiment.

Fourth Embodiment

The electric actuator100of the first embodiment described above includes a single drive unit100d, but a plurality of drive units may be provided to an electric actuator. An electric actuator200according to a fourth embodiment of the present disclosure described next includes four drive units200d. The electric actuator200may include a servo amplifier295(drive device), which is described later with reference toFIG.16, and the controller96.

FIG.11is a perspective view of the electric actuator200according to the fourth embodiment of the present disclosure.FIGS.12through14are side, plan, and front views of the electric actuator200, respectively.FIG.15is a configuration diagram of a crankshaft270of the electric actuator200.

The electric actuator200according to the fourth embodiment of the present disclosure is a four-cylinder actuator that mimics a structure of a four-cylinder engine, and includes a crankshaft270and four drive units200dconnected to the crankshaft270. In other words, the electric actuator200includes four electric motors, four first motion converters, and four second motion converters, with the four second motion converters sharing an output shaft for unidirectional rotary motion as described below. The electric actuator200further includes the servo amplifier295(drive device), which is described later with reference toFIG.16, and the controller96.

Each drive unit200dhas a structure similar to the drive unit100dof the first embodiment and includes the motor10, the shaft coupling20, the bearing30, the ball screw40, a piston250, and a connecting rod260, as shown inFIG.11.

As shown inFIG.12, the motor10is fixed to a frame220which houses the shaft coupling20, and the frame220is fixed on a base210. As shown inFIG.13, the output shaft of the motor10is connected by the shaft coupling20to the shaft of the ball screw40, which is supported by the bearing30provided to the frame220.

A piston250is fixed to the nut of the ball screw40. As shown inFIG.12, the piston250is placed on a carriage242that can move along a rail241, which is disposed parallel to the shaft of the ball screw40on a top surface of a frame230. By placing the piston250on the carriage242in this manner, the linear motion of the piston250is guided by the rail241and the carriage242. This prevents excessive bending stress from acting vertically to the ball screw40as the piston250performs its reciprocating linear motion.

As shown inFIGS.12and13, an end part251of the piston250is rotatably connected to one end (clevis section) of the connecting rod260by a pin252(first pin). As a result, the connecting rod260can rotate within a certain angular range with the pin252as a central axis of rotation in association with the reciprocating linear motion of the piston250. As shown inFIGS.13and14, the other end of the connecting rod260is rotatably connected to the crankshaft270by a crank pin273.

The crankshaft270is a rotating body and has a structure that mimics a crankshaft for a four-cylinder engine. As shown inFIG.15, the crankshaft270consists of a plurality of parts, which are fixed to each other with bolts. With such configuration, the crankshaft can be easily configured for any number of drive units d, not just for the four-cylinder type.

Specifically, as shown inFIGS.14and15, the crankshaft270includes crank journals (crank journals271and crank journals272) supported by bearings provided in bearing sections (bearing sections281and bearing sections282) standing from the base210, the crank pins273rotatably connected to the connecting rods260, and crank arms274that joint the crank pins273at eccentric positions with respect to axes of the crank journals. The crank pins273are eccentric pins eccentric with respect to an axis of rotation of the crankshaft270.

The crank journals271and272and the crank pins273are bolted to the crank arms274, respectively, and the crank journals271and272and the crank pins273are connected to each other via the crank arms274.

The crankshaft270includes two types of crank journals: the crank journal271which has an output shaft, and the crank journal272which is sandwiched between crank arms274. The crank journal272sandwiched between the crank arms274consists of two parts (a crank journal272aand a crank journal272b) to allow insertion into the bearing, and after inserting one part (the crank journal272a) into the bearing, the other part (the crank journal272b) is bolted to form one part.

In the electric actuator200configured as described above, the reciprocating rotary motion of the motor10is converted into the reciprocating linear motion of the piston250by the ball screw40. The reciprocating linear motion of the piston250is further converted into a unidirectional rotary motion of the crankshaft270by the connecting rod260and the crankshaft270constituting a slider-crank mechanism. That is, as with the electric actuator200of the first embodiment, the electric actuator200is configured to convert the reciprocating rotary motion of the motor10into the unidirectional rotary motion for output.

The electric actuator200differs from the electric actuator100in that the connecting rods260of the four drive units200dare rotatably fitted to the four crank pins273of the crankshaft270, respectively. In the electric actuator200, the crankshaft270is rotationally driven by the four drive units200dconnected to the crankshaft270. In other words, the four drive units200dshare the crankshaft270, which is the output shaft of the unidirectional rotary motion output by their respective crank mechanisms, so that the power generated by the four drive units200dis combined at the crankshaft270. This also makes the electric actuator200different from the electric actuator100.

The eccentric directions of the four crank pins273included in the crankshaft270are not limited, but may be different from each other. For example, the eccentric directions of the four crank pins273may be alternately made different by 180°. For example, the eccentric directions of the four crank pins273may be made different by 90° so that timings at which the four crank pins273come to respective dead points do not coincide. Smooth rotation may be realized by eliminating time when no rotational force is acting on the crankshaft270with this configuration.

FIG.16is a block diagram showing a schematic configuration of an electric power feeding system290S (electric drive system290) of the electric actuator200according to the fourth embodiment of the present disclosure. The electric power feeding system290S, together with the four drive units200d(specifically, the motors10), constitute the electric drive system290.

The electric drive system290and the electric power feeding system290S of the fourth embodiment differ from the first embodiment in that the electric drive system290and the electric power feeding system290S include a plug291that is plugged into an outlet of a primary power source (not shown) and in the configuration of the servo amplifier. The servo amplifier295of the fourth embodiment includes a battery295eand four inverters95bcorresponding to the four drive units200d, respectively. Due to the inclusion of the battery295e, the electric actuator200of the fourth embodiment can be operated using electric power accumulated in the battery295eeven when the electric actuator200is disconnected from the primary power source. The battery295eis connected to the direct current bus bar95dconsisting of a pair of conductors in parallel with the power regenerative converter95aand the four inverters95b. Each inverter95bis connected to the motor10of the corresponding drive unit200d.

The four inverters95bare connected in parallel with each other to one common system of the direct current bus bar95d. That is, direct current electric powers generated by the power regenerative converter95a, the battery295e, and the capacitor95care distributed to the four inverters95b. The regenerative electric powers output from the four inverters95bare combined in the direct current bus bar95d. A portion of the regenerative electric power returned to the direct current bus bar95dis again distributed to the four inverters95b. Excess regenerative electric power is stored in the capacitor95cand the battery295e, or returned to the primary power source via the power regenerative converter95a.

If the eccentric directions of the four crank pins273are alternately made different by 90° (i.e., the eccentric directions of the four crank pins273are 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock), the motors10of the two drive units200dthat are connected to the eccentric crank pins273of the crankshaft270being eccentric in the 12 o'clock and 6 o'clock directions and the motors10of the remaining two drive units200dthat are connected to the eccentric crank pins273of the crankshaft270being eccentric in the 3 o'clock and 9 o'clock directions have opposing electric power consumption/regeneration timings, so that most of the regenerative electric power output from the motors10of one of the two sets of the two drive units200dare efficiently consumed by the motors10of the other of the two sets of the two drive units200d. Therefore, it is possible to drive the electric actuators200with lower electric power consumption.

Fifth Embodiment

FIG.17is a perspective view of an electric actuator201according to a fifth embodiment of the present disclosure.FIG.18is a plan view of the electric actuator201.

As shown inFIG.17, the electric actuator201according to the fifth embodiment of the present disclosure includes a crankshaft270aand two drive units200dconnected to the crankshaft270a. The drive units200dare as described above in the fourth embodiment, and a detailed description is omitted. In other words, the electric actuator201includes two electric motors, two first motion converters, and two second motion converters, with the two second motion converters sharing an output shaft for unidirectional rotary motion. As in the electric actuator200, the electric actuator201may include the servo amplifier295(drive device) and the controller96.

The crankshaft270ahas a structure that mimics a crankshaft for a two-cylinder engine. Like the crankshaft270of the fifth embodiment, the crankshaft270aconsists of a plurality of parts, and the plurality of parts are fixed to each other with bolts.

Specifically, as shown inFIG.18, the crankshaft270aincludes crank journals (the crank journals271and the crank journal272) supported by bearings provided in bearing sections (the bearing sections281and the bearing section282) standing from the base210, the crank pins273rotatably connected to the connecting rods260, and crank arms274that joint the crank pins273at eccentric positions with respect to axes of the crank journals. The crankshaft270adiffers from the crankshaft270in that the crankshaft270ahas fewer parts than the crankshaft270due to the reduced number of cylinders (number of drive units). For example, there is only one crank journal272provided between cylinders and only two crank pins273provided per cylinder.

In the first through fifth embodiments described above, a crank mechanism (slider crank mechanism) consisting of a connecting rod and a crankshaft is employed as the second motion converter that converts reciprocating motion (reciprocating linear motion) into unidirectional rotary motion, but the present disclosure is not limited to this configuration. Embodiments that do not use a crankshaft are described below.

Sixth Embodiment

FIG.19shows an external view of an electric actuator300according to a sixth embodiment of the present disclosure. The electric actuator300of the present embodiment includes a base304, and a drive unit300dand a spindle section370installed on the base304. As in the electric actuators according to the embodiments described above, the electric actuator300may include a servo amplifier and a controller which are not shown in the figure.

The drive unit300dincludes the motor10, the ball screw40that converts the rotary motion of the motor10into linear motion, the bearing30that rotatably supports the screw shaft41of the ball screw40, a box-shaped linear motion part350(hereinafter referred to as “piston350”) that can move in the axial direction (i.e., in the extending direction of the axis line Ax1), and a guideway-type circulating linear bearing354(hereinafter referred to as “linear guide354”) that movably supports the piston350in the axial direction, a connecting rod360that connects the piston350to a spindle372described below in the spindle section370, and a frame305and a frame306mounted on the base304. The motor10and the bearing30are attached to the frame305. The axis line Ax1of the drive unit300dof the present embodiment is a straight line common to the centerlines of the shaft11of the motor10and the screw shaft41of the ball screw40.

The linear guide354includes a rail354aand a carriage354bthat can travel on the rail354a. The rail354ais attached to a top surface of a frame306, and the carriage354bis attached to a bottom surface of the piston350. This allows the piston350to be supported to be movable only in the axial direction with respect to the base304.

The shaft11(not shown) of the motor10is connected to the screw shaft41of the ball screw40by the shaft coupling20. The nut42(not shown) of the ball screw40is housed in a hollow portion of the piston350and secured to the piston350. As the shaft11of the motor10rotates back and forth, the piston350moves back and forth in the axial direction. A clevis351is provided at one end of the piston350in the axial direction.

The spindle section370includes a spindle372which is a rotating body, and a bearing section374that rotatably supports the spindle372. A pin372pis eccentrically mounted on one end surface of spindle the372. That is, the pin372pis an eccentric pin that is eccentric with respect to the axis of rotation of the spindle372.

Ball joints362are provided at both end portions of the connecting rod360according to the present embodiment. One ball joint362is connected to the clevis351via the pins52to be rotatable around the pin52. The other ball joint362is connected to the spindle372via the pin372pto be rotatable around the pin372p. A rolling bearing such as a spherical roller bearing or a spherical ball bearing may be used in place of the ball joint362.

The motor10is driven so that the shaft11repeatedly rotates back and forth within a predetermined angular range. The rotation of the motor10is converted into linear motion by the ball screw40and transmitted to the piston350. As a result, the piston350moves in a reciprocating linear motion along the axis line Ax1with a predetermined stroke. That is, the ball screw40functions as the first motion converter that converts the reciprocating rotary motion output from the motor10into the reciprocating linear motion. The reciprocating linear motion of the piston350in the direction of the axis line Ax1is transmitted by the connecting rod360to the pin372pand converted into a unidirectional rotary motion of the spindle372. That is, the connecting rod360and the spindle372constitute a link mechanism as the second motion converter that converts the reciprocating motion (reciprocating linear motion) into the unidirectional rotary motion.

Seventh Embodiment

FIG.20is an external view of an electric actuator400according to a seventh embodiment of the present disclosure. The electric actuator400of the present embodiment includes two drive units400ddisposed side by side, and a gear device470connected to the two drive units400d. As in the electric actuators of the embodiments described above, the electric actuator400may include a servo amplifier and a controller which are not shown. A configuration of the drive unit400dof the present embodiment differs from that of the drive unit300dof the sixth embodiment in that a frame405of the two drive units400dis integrated, but the other configuration is common to the drive unit300d.

FIG.21is a diagram showing a mechanism of the gear device470. The connecting rods360of the drive units300dare also illustrated inFIG.21.

The gear device470includes a case471(FIG.20), two pairs of bearings473and476attached to the case471, a first shaft472(input shaft) rotatably supported by the pair of bearings473, a drive gear474attached to the first shaft472, a second shaft475(output shaft) rotatably supported by the pair of bearings476, and a driven gear477attached to the second shaft475. The drive gear474meshes with the driven gear477, and rotary motion of the first shaft472is transmitted to the second shaft475via the drive gear474and the driven gear477.

Disk parts472aare provided to both ends of the first shaft472, respectively. A pin472pis eccentrically attached to each disk part472a. In the present embodiment, eccentric directions of the pins472pof the two disk parts472aare 90 degrees apart.

The connecting rod360of one of the drive units400dis connected to the pin472pof one of the disk parts472aof the first shaft472, and the connecting rod360of the other of the drive units400dis connected to the pin472pof the other of the disk parts472aof the first shaft472. Therefore, outputs from the pair of drive units400dare combined in the gear device470(more specifically, the first shaft472) and output from the second shaft475.

In the present embodiment, the eccentric directions of the pins472pof the two disk parts472a, which are coupled to the connecting rods360of the two drive units400d, respectively, are 90 degrees apart. Therefore, the motors10of the two drive units400dhave opposite timing of electric power consumption/regeneration to each other, so that most of the regenerative electric power output from the motor10of one of the drive units400dis efficiently consumed by the motor10of the other of the drive units400d. Therefore, it is possible to drive the electric actuator400with lower electric power consumption.

In the first through seventh embodiments described above, a configuration in which reciprocating rotary motion is once converted into reciprocating linear motion by the first motion converter and then further converted into unidirectional rotary motion by the second motion converter is employed. However, the present disclosure is not limited to this configuration, and configurations in which the reciprocating rotary motion is directly converted into unidirectional rotary motion are also included in the scope of the disclosure, as in an eighth embodiment of the present disclosure described next.

Eighth Embodiment

FIG.22is an external view of an electric actuator500of the eighth embodiment of the present disclosure. The electric actuator500of the present embodiment includes a base504, and a drive unit500dand spindle section570installed on the base504. The electric actuator500may include the servo amplifier95and the controller96shown inFIG.23. The drive unit500dincludes the motor10, a drive disk550(first disk part) coupled to the shaft11of the motor10, and a connecting rod560. A pin552(first pin) is eccentrically attached to the drive disk550.

The spindle section570includes a spindle572, and a bearing section574that rotatably supports the spindle572. The spindle572includes a cylindrical shaft part572b, a driven disk572a(second disk part) coupled to one end of the shaft part572b, and a pin572p(second pin) eccentrically attached to the driven disk572a.

Ball joints562are provided at both ends of the connecting rod560. One of the ball joints562is connected to the drive disk550via the pin552and rotatably around the pin552. The other of the ball joints562is connected to the driven disk572a(spindle572) via the pin572pand rotatably around pin572p. That is, the connecting rod560is coupled to the drive disk550(pin552) and the driven disk572a(pin572p) with joints (pairs of elements). A rolling bearing such as a self-aligning roller bearing or a self-aligning ball bearing may be used in place of the ball joint562.

The motor10is driven so that the shaft11(and the drive disk550) repeatedly rotates back and forth within a predetermined angular range. The connecting rod560is thereby repeatedly pushed and pulled in a lengthwise direction in a predetermined stroke and, as a result, the driven disk572a(spindle572) rotates continuously in one direction. That is, the reciprocating rotary motion of the motor10is converted into a unidirectional rotary motion of the spindle572by a link mechanism consisting of the drive disk550, the connecting rod560, and the driven disk572a. This link mechanism can also be interpreted as a combination of two crank mechanisms (specifically, a first crank mechanism, as a first motion converter, consisting of the drive disk550and the connecting rod560, and a second crank mechanism, as a second motion converter, consisting of the connecting rod560and driven disk572a).

The spindle section570of the present embodiment (more specifically, the bearing section574) has a generator80(FIG.23) built therein.

FIG.23is a block diagram showing a schematic configuration of an electric power feeding system590S (electric drive system590) of the electric actuator500according to the eighth embodiment of the present disclosure. The electric power feeding system590S, together with the motor10, constitutes the electric drive system590.

The electric drive system590and the electric power feeding system590S of the eighth embodiment differ from the electric drive system90and the electric power feeding system90S of the first embodiment in that the electric drive system590and the electric power feeding system590S include a generator80, and an inverter device97that converts electric power generated by the generator80into system electric power (e.g., three-phase alternating current) and supplies the electric power to a primary power source side. The inverter device97is communicatively connected to the controller96and operates in accordance with the control of by controller96.

The inverter device97includes a converter97a, an inverter97b, and a capacitor97c. For example, the converter97aincludes a full-wave rectifier including a diode bridge circuit. A PWM converter may be provided on an input side of converter97ato sinusoidalize input current of the converter97a. The inverter97bis, for example, a PWM inverter that controls output electric power by PWM control.

The electric power generated by the generator80is converted into direct current by the converter97a, smoothed by the capacitor97c, and then input to the inverter97b. A pair of positive and negative conductors constitute one system of a direct current bus bar97d. The inverter97bconverts the direct current electric power supplied from the direct current bus bar97dinto a sinusoidal alternating current of the same quality as the system electric power and outputs the sinusoidal alternating current to the primary power source91side.

According to the present embodiment, electric energy can be used more efficiently because electric power is generated by the generator80and supplied to the primary power source91side not only during regenerative operation but also during power operation.

In the present embodiment, the generator80is built into the bearing574of the spindle section570. However, the generator80may be provided in the drive unit500d. For example, the generator80may be installed between the motor10and the drive disk550. The shaft11of the motor10or the shaft part572bof the spindle572may be extended and connected to an input shaft of the generator80to supply a portion of the electric power to the generator80. A portion of the electric power may also be diverted from a rotary shaft of the drive unit500dor spindle section570and transmitted to the generator80by means of a belt, chain, or other winding transmission or gear mechanism.

The generator80of the present embodiment is an AC generator, but a DC generator may also be used. In this case, the converter97aof the inverter device97is not needed because rectification of the electric power generated by the generator is not required, and, for example, an output terminal of the DC generator is connected to the direct current bus bar97dwithout going through the converter97a.

A battery may be provided to the inverter device97, and the battery may be connected to the direct current bus bar97din parallel with the capacitor97c.

A clutch may be provided between the generator80and the motor10, and timing of electric power absorption by the generator80may be controlled by intermittency of the clutch.

The direct current bus bar97d, the capacitor97c, and the inverter97bof the inverter device97may be shared between the direct current bus bar95d, the capacitor95c, and the power regenerative converter95aof the servo amplifier95, respectively.

Next, exemplary applications of the electric actuators according to the embodiments of the present disclosure will be described.

Ninth Embodiment

FIG.24is a diagram showing a schematic configuration of a power system of an electric car1equipped with the electric actuator200according to the fourth embodiment of the present disclosure as a prime mover. The electric car1includes a power transmission2, and left and right drive shafts3aand3b. The power transmission2includes a transmission, a final reduction gear, and a differential which are not shown. The crankshaft270of the electric actuator200is connected to an input shaft of the power transmission2. The drive shafts3aand3bare connected to the left and right output shafts of the power transmission2, respectively. A wheel W is attached to a distal end of each of the drive shafts3aand3b. Power output from the electric actuator200is transmitted to the drive shafts3aand3bvia the transmission, the final reduction gear and the differential of the power transmission2to rotationally drive the wheels W attached to the distal ends of the drive shafts3aand3b.

The electric actuators according to the embodiments of the present disclosure can be used in place of various prime movers that output rotary motion (e.g., engines, electric motors, hydraulic motors, air motors, steam turbines, etc.).

The exemplary application shown inFIG.24is an example of the electric actuators according to the embodiments of the present disclosure applied to a four-wheeled electric car, but the electric actuators according to the embodiments of the present disclosure can be used in various types of cars such as two-wheeled cars, three-wheeled cars, cars with six or more wheels such as trucks, buses, and tractors. Furthermore, the electric actuators according to the embodiments of the present disclosure can be used not only for electric cart but also for hybrid cars.

The electric actuators according to the embodiments of the present disclosure can be used not only as prime movers for cars but also as prime movers for railroad vehicles.

Tenth Embodiment

A tenth embodiment described next is an example of the application of the present disclosure to a railroad system.FIG.25is a diagram showing a schematic configuration of a drive mechanism of a railroad car600according to the tenth embodiment of the present disclosure. The railroad car600includes a plurality of (in the example shown inFIG.25, three) bogies601. The bogie601is a dynamic bogie including the electric actuator200according to the fourth embodiment of the present disclosure as a drive device.

The bogie601includes two electric actuators200, two pairs of axles603(axles603aand axles603b), two pairs of bearings602, two pairs of axle boxes (not shown), two pairs of axle box support devices (not shown), and two pairs of wheels604. One end of the axle603aand one end of the axle603bare connected to both ends of the crankshaft270of electric actuator200. The wheels604are attached to the other ends of the axles603aand603b.

The bearings602are attached to respective axle boxes, and the axle boxes are attached to the bogie frame605via respective axle box support devices. The bearings602and the axle boxes are buffer-supported with respect to the bogie frame605(frame) by the axle box support devices. The axles603aand603bare rotatably supported by respective bearings602.

FIG.26is a block diagram showing a schematic configuration of an electric power feeding system690S (electric drive system690) of the railroad car600according to the tenth embodiment of the present disclosure. The electric power feeding system690S, together with a plurality of electric actuators200(specifically, a plurality of motors10) mounted on the railroad car600, constitutes the electric drive system690.

The railroad car600is a dynamic car that collects electric power using an overhead line electric power collection system and includes, as an electric power collector, a pantograph691cthat contacts an overhead line691bwhich is a trolley line (contact wire). The overhead line691bis supplied with system electric power (e.g., three-phase AC) from an electric power substation691a.

Of the electric drive system690(electric power feeding system690S), a mobile drive system690M (mobile electric power feeding system690MS) installed in the railroad car600consists of one or more mobile drive units690MU (mobile electric power feeding system690MSU) unitized for each corresponding bogie601. The mobile drive unit690MU (mobile electric power feeding system690MSU) may be configured not in units of bogies601, but in units of railroad cars600, or in units of trains with multiple railroad cars600connected.

According to the electric drive system690according to the tenth embodiment of the present disclosure, the same effect as that of the electric drive system290according to the second embodiment of the present disclosure is obtained. That is, since regenerative electric power is efficiently used to drive the motor10, it is possible to drive the railroad car600(electric actuator200) with low electric power consumption.

In the present embodiment, the overhead line electric power collection system using pantograph692cas an electric power collector is employed, but other types of electric power collectors (e.g., view gels, trolley poles, etc.) or other types of electric power collection systems (e.g., third rail system in which electric power collecting shoes contact the electric power feeding rail [third rail] to collect electric power) may be used.

The railroad car600of the present embodiment is a bogie type railroad car that uses the bogies601as a traveling device and the mobile drive unit690MU is mounted on the bogie601, but the present disclosure is not limited to this configuration. For example, the traveling device and the mobile drive unit690MU may be directly installed in the car body.

In the present embodiment, the mobile drive unit690MU (specifically, a servo amplifier695) of each bogie601includes a battery295e, but the battery295emay be shared by the mobile drive units690MU of the plurality of bogies601. In this case, for example, the battery295emay be provided only in the servo amplifier695of one (or some) of the plurality of bogies601, and the direct current bus bars95dof said plurality of bogies601may be connected to each other. The battery295emay also be disposed outside of the servo amplifier695(e.g., on the car body) and connected to the direct current bus bars95dof said plurality of bogies601.

In the present embodiment, the configuration in which the split axles603aand603bare directly connected to both ends of the crankshaft270of the electric actuator200is employed. However, the present disclosure is not limited to this configuration. For example, the electric actuator200and an undivided axle603may be connected via a power transmission device such as a gear device.

In the present embodiment, a shaft box support system which uses a shaft box and a shaft box support device is employed. However, the present disclosure is not limited to this configuration.

Eleventh Embodiment

Next, an example of the application of the present disclosure to a tire testing device will be described. A tire testing device according to an eleventh embodiment of the present disclosure described below is a testing device capable of performing wear tests, endurance tests, driving stability tests and the like on tires.

FIGS.27and28are perspective views of a tire testing device2000according to the eleventh embodiment of the present disclosure, viewed from different directions. The tire testing device2000of the present embodiment includes a rotating drum2010with a simulated road surface formed on its outer circumference, an alignment adjustment mechanism2160that holds a tire T rotatably with the tire T grounded in a predetermined posture on the simulated road surface, a torque generator130(slip rate controller) that generates torque to be applied to the tire T, and an inverter motor2080that rotationally drives the rotating drum2010and a casing of the torque generator130.

The rotating drum2010is rotatably supported by a pair of bearings2011a. A pulley2012ais attached to an output shaft of the inverter motor2080, and a pulley2012bis attached to one of shafts of the rotating drum2010. The pulley2012aand the pulley2012bare connected by a drive belt2015(e.g., toothed belt). The other of the shafts of the rotating drum2010has a pulley2012cattached via a relay shaft2013. The relay shaft2013is rotatably supported by a bearing2011bnear one end portion where the pulley is attached. The pulley2012cis connected to a pulley2012dby a drive belt2016. The pulley2012dis coaxially fixed to a pulley2012eand is rotatably supported by a bearing2011c(FIG.28) together with the pulley2012e. The pulley2012eis also connected to a shaft part131aof a later-described casing131of the torque generator130by a drive belt2017.

FIG.29is a diagram showing an internal structure of the torque generator130. The torque generator130includes a casing131, and the servomotor10and a reduction gear133fixed inside the casing131. In the present embodiment, the servomotor10of the same configuration as in the first embodiment is used. Cylindrical shaft parts131aand131bare formed at both ends of the casing131in an axial direction. The casing131is rotatably supported by bearing sections2020and2030at the shaft parts131aand131b. A pulley2012fis attached to an outer circumference of the shaft part131aat one end (right end inFIG.29).

The reduction gear133has an input shaft133aand an output shaft133b. Rotary motion input to the input shaft133ais reduced and output to the output shaft133b. The input shaft133aof the reduction gear133is connected to a drive shaft150aof the servomotor10by a coupling134. The output shaft133bof the reduction gear133is connected to a coupling shaft135. It is noted that the reduction gear133is optionally provided in the torque generator130. The coupling shaft135may be directly connected to the drive shaft150aof the servomotor10without providing the reduction gear133in the torque generator130.

The coupling shaft135is passed through a hollow portion of the cylindrical shaft part131aof the casing131and is rotatably supported by a pair of bearings136provided on an inner circumference of the shaft part131a. A distal end of the coupling shaft135protrudes from a distal end of the shaft part131a. The coupling shaft135protruding from the shaft part131ais connected to a spindle of the alignment adjustment mechanism2160via a constant velocity joint2014(FIG.27). A wheel on which a tire T is mounted is attached to the spindle of the alignment adjustment mechanism2160.

As a result, when the inverter motor2080is driven, the rotating drum2010rotates and the casing131of the torque generator130connected to the inverter motor2080via the rotating drum2010rotates. When the torque generator130is not activated, the rotating drum2010and the tire T rotate in opposite directions so that their peripheral speeds at the contact area are the same. By activating the torque generator130, dynamic or static driving and braking forces can be applied to the tire T.

In the present embodiment, power output from the inverter motor2080is again transmitted to the rotating drum2010via the rotating drum2010, the relay shaft2013, the torque generator130, the constant velocity joint2014, the spindle of the alignment adjustment mechanism2160, and the tire T. That is, the power transmission path consisting of the rotating drum2010, the relay shaft2013, the torque generator130, the constant velocity joint2014, the spindle of the alignment adjustment mechanism2160, and the tire T constitutes a power circulation system. Therefore, the power of the inverter motor2080is used efficiently, thereby enabling operation with less power consumption.

The alignment adjustment mechanism2160of the present embodiment is a mechanism that rotatably supports the tire T, which is a test specimen, in a state in which the tire T is mounted on a wheel, presses a tread portion of the tire T against the simulated road surface of the rotating drum2010, and adjusts orientation of the tire T relative to the simulated road surface and tire load (contact pressure) to set conditions. The alignment adjustment mechanism2160includes a tire load adjustment section2161that adjusts the tire load by moving a position of a rotation axis of the tire T in a radial direction of the rotating drum2010, a slip angle adjustment section2162that adjusts a slip angle of the tire T relative to the simulated road surface by tilting the rotation axis of the tire T around a perpendicular line of the simulated road surface, a camber angle adjustment section2163that adjusts a camber angle by tilting the rotation axis of the tire T relative to a rotation axis of the rotating drum2010, and a traverse device2164that moves the tire T in the direction of the rotation axis. The tire load adjustment section2161, the slip angle adjustment section2162, the camber angle adjustment section2163, and the traverse device2164include servomotors M1, M2, M3, and M4, respectively. The servomotors M1, M2, M3and M4are, for example, AC servomotors.

FIG.30is a block diagram showing a schematic configuration of an electric power feeding system2800S (electric drive system2800) of the eleventh embodiment of the present disclosure, which provides electric power to the servomotor10and the inverter motor2080.

The electric power feeding system2800S of the present embodiment differs from the electric power feeding system90S of the first embodiment in that the electric power feeding system2800S has an electric power feeding structure2860(a reactor2870and a driver2880) that supplies electric power to the inverter motor2080branched from a rear stage of an electromagnetic switch2830, and electric power feeding structures2891(a reactor R1and a servo amplifier A1),2892(a reactor R2and a servo amplifier A2),2893(a reactor R3and a servo amplifier A3), and2894(a reactor R4and a servo amplifier A4) that supply electric power to the servomotors M1, M2, M3, M4of the alignment adjustment mechanism2160, respectively. The driver2880is a device that generates driving electric power for the inverter motor2080and includes an inverter circuit not shown. The driver2880and the servo amplifiers A1to A4are each communicatively connected to a controller C2and operate according to control by the controller C2. The servo amplifiers A1, A2, A3, and A4have the same configuration as a servo amplifier2850. The servo amplifier2850includes a power regenerative converter2851, an inverter2852, a capacitor2853, and a direct current bus bar2854connecting these components.

In a test using the tire testing device2000of the present embodiment, electric power supplied from a primary power source2810is supplied to the servo amplifier2850via a circuit breaker2820, the electromagnetic switch2830, and a reactor2840, thereby driving the servomotor10. The electric power supplied from the primary power source2810is also supplied to the driver2880via the circuit breaker2820, the electromagnetic switch2830, and the reactor2870, thereby driving the inverter motor2080. The electric power supplied from the primary power source2810is further supplied to the servo amplifiers A1, A2, A3, and A4via the circuit breaker2820, the electromagnetic switch2830, and the reactor R1, R2, R3, and R4, thereby driving the servomotors M1, M2, M3, and M4. As a result, the tire T is given a rotary motion that is a composite of the rotation speed output by the inverter motor2080and the torque generated by the torque generator130(specifically, the servomotor10) in a state where the tire T is given arbitrary tire load, slip angle, and camber angle.

In one example of the test using the tire testing device2000, the inverter motor2080is controlled to output a constant rotation speed and the servomotor10is controlled to output fluctuating torque (e.g., random oscillating torque). Specifically, the servomotor10is driven to rotate back and forth with varying amplitude and period based on predetermined vibration waveform data. That is, the motor10is controlled by controller C2to repeat forward and reverse rotations. As a result, acceleration and deceleration of the servomotor10are repeated, and the supply of driving electric power from the servo amplifier2850to the servomotor10and supply of regenerative electric power from the servomotor10to the servo amplifier2850are repeated.

Most of the regenerative electric power generated by the servomotor10is temporarily accumulated in the capacitor2853and is then used to drive the servomotor10. Surplus of the regenerative electric power is supplied to the electric power feeding structures2860,2891,2892,2893,2894via the power regenerative converter2851and the reactor2840and used to drive the inverter motor2080and servomotors M1, M2, M3, M4. Therefore, most of the regenerative electric power generated by the servomotor10is reused to drive the servomotors10, M1to M4, and the inverter motor2080, and electric power consumption from the primary power source2810used to drive the servomotor10is slightly reduced. Regenerative electric power generated by the inverter motor2080and the servomotors M1, M2, M3, and M4is also reused to drive the other motors (i.e., the servomotors10, M1, M2, M3and M4, and the inverter motor2080), further reducing the electric power consumption from the primary power source2810.

By setting the tire T to the tire testing device2000having the configuration described above and driving the inverter motor2080for rotation drive, the tire T and the rotating drum2010rotate at the same peripheral speed. In this state, the servomotor10of the torque generator130is driven to apply driving force or braking force to the tire T, thereby enabling tire wear tests, endurance tests, driving stability tests and the like that simulate actual driving conditions.

In the present embodiment, the inverter motor2080is used to rotate the tire T and the rotating drum2010at the same peripheral speed. However, in place of the driver2880and the inverter motor2080inFIG.30, the electric actuator100according to the first embodiment including the servomotor10and the drive unit100dmay be used. That is, instead of attaching the pulley2012adirectly to the output shaft of the servomotor10, the drive unit100dthat converts the reciprocating rotation of the servomotor10into unidirectional rotation may be provided between the servomotor10and the pulley2012a. This allows regenerative energy to be used for the operation of rotating the tire T and the rotating drum2010at the same peripheral speed.

Twelfth Embodiment

A multi-test device according to a twelfth embodiment of the present disclosure described below is a test device capable of performing uniformity and dynamic balance tests of tires.FIG.31is a side view showing a basic configuration of a uniformity and dynamic balance multi-test device3000(hereinafter referred to as the multi-test device3000).FIG.32is a diagram schematically showing a method of rotationally driving a spindle3120of the multi-test device3000.

As shown inFIG.31, the multi-test device3000is configured to hold the tire T between a lower rim3010and an upper rim3020at the top and bottom. More precisely, the multi-test device3000nips and holds the tire T between the lower rim3010and the upper rim3020by inserting and securing a locking shaft3300, to which the upper rim3020is fixed at the upper end, to the spindle3120.

In the uniformity test, a rotating drum3030provided on a side of the spindle3120is used. The rotating drum3030is mounted on a movable housing3032that is slidable on rails3031extending in approaching and separating directions with respect to the tire T, and moves in the approaching and separating directions with respect to the tire T by a rack and pinion mechanism3035(pinion3036and rack3038) driven by a motor not shown. The rotating drum3030can be rotated at any desired rotation speed by an electric actuator (hereinafter referred to as “electric actuator100a”) not shown. A configuration of the electric actuator100ais the same as that of the electric actuator100described above in the first embodiment.

When conducting the uniformity test, the rotating drum3030is brought into contact with the tire T by the rack and pinion mechanism3035, and the rotating drum3030is then pressed against the tire T with a force of several hundred kgf or more. The rotating drum3030is then rotated in this state (thus the tire T in contact with the rotating drum3030also rotates along with the rotating drum3030), and variation in force generated on the rotating tire is measured from load fluctuation at this time with a triaxial piezoelectric element installed on a side surface of a spindle housing3110.

In the present embodiment, the rotating drum3030is rotated using the electric actuator100a. This allows the3030rotating drum to rotate while utilizing regenerative energy to perform the uniformity test.

On the other hand, the dynamic balance test is a test that measures eccentricity of the tire by rotating the tire T together with the spindle3120in a state where the rotating drum3030is separated from the tire T, and measuring the eccentricity of the tire from an oscillating force generated by imbalance of the tire T at that time.

At a lower end of spindle3120, a pulley3140for rotationally driving the spindle3120during dynamic balance tests is attached. An electric actuator100b, which can move horizontally toward the spindle3120by means of a rack and pinion mechanism not shown, is installed on a base3050to which the spindle3120is fixed, and the spindle3120is rotated by the electric actuator100b. A configuration of the electric actuator100bis the same as the electric actuator100described above in the first embodiment. This allows the spindle3120to be rotated while utilizing regenerative energy to perform dynamic balance tests.

A drive pulley3144is attached to an output rotary shaft of the electric actuator100bat the same height as the pulley3140of the spindle3120. As shown inFIG.32, a pair of driven pulleys3143are rotatably installed at the same height as the drive pulley3144and the pulley3140of the spindle3120. The driven pulleys3143move back and forth together with the electric actuator100b(the drive pulley3144) by the above-mentioned not-shown rack and pinion mechanism. An endless belt3142is tacked across the drive pulley3144and the driven pulleys3143, and the endless belt3142can be made to advance at a predetermined speed with the electric actuator100b.

By driving the electric actuator100bin the state where the endless belt3142is in contact with the pulley3140(a state shown with a solid line inFIG.32) by the rack-and-pinion mechanism, the pulley3140rotates and the spindle3120rotates with the tire T held between the lower rim3010and the upper rim3020. At this time, the excitation force is measured by the triaxial piezoelectric element installed on the side surface of the spindle housing3110.

In the present embodiment, the electric actuator100bcan be used to rotate the spindle3120while using regenerative energy to perform dynamic balance tests.

That is, the multi-test device3000is provided with two electric actuators100aand100bthat are identical to the electric actuator100of the first embodiment, with electric actuator100aused to rotate the rotating drum3030and the electric actuator100bused to rotate the spindle3120. This allows tests to be conducted while utilizing regenerative energy for both uniformity and dynamic balance tests.

Thirteenth Embodiment

A balance measurement device4000according to a thirteenth embodiment of the present disclosure described below is a test device capable of measuring balance of a rotating body.FIGS.33and34are a front view and a side view, respectively, of the balance measurement device4000according to the embodiment of the present disclosure. In the following description, a vertical direction inFIG.33is defined as a Y-axis direction, and a direction perpendicular to both the vertical direction and a rotation axis direction of the rotating body is defined as an X-axis direction. The rotating body4100in the present embodiment is, for example, a crankshaft, and the balance measurement device4000is, for example, a device for measuring the balance of the crankshaft.

A device frame of the balance measurement device4000consists of a base4013, a plurality of springs4014extending vertically upward from the base4013, and a table4015supported by the springs4014. Drive shaft bearings4012aand4012bare attached to a lower surface of the table4015. A drive shaft4005is rotatably supported by the drive shaft bearings4012aand4012b. As shown inFIG.34, a first side wall4013aand a second side wall4013b, which can be regarded as almost rigid, extend vertically upward from both ends of the base4013in the X-axis direction.

The electric actuator100according to the first embodiment is attached to the base4013. A pulley4003is attached to a drive shaft of the electric actuator100. On the other hand, a first pulley4006is attached to one end of the drive shaft4005, and a first endless belt4004is tacked across this first pulley4006and the pulley4003attached to the drive shaft of the electric actuator100. By driving the electric actuator100, the drive shaft4005can be driven to rotate via the first endless belt4004.

A first table side wall4017aand the second table side wall4017bthat are parallel to each other are fixed vertically above a top surface of the table4015. The first table side wall4017aand the second table side wall4017bare rigid bodies having extremely high rigidity compared to a spring constant of the springs4014. Driven shaft bearings4016aand4016care fixed to the first table side wall4017a, and driven shaft bearings4016band4016dare fixed to the second table side wall4017b. Only the driven shaft bearings4016aand4016bare shown inFIG.33, while the driven shaft bearings4016cand4016dare disposed on the far side of the driven shaft bearings4016aand4016binFIG.33, respectively. The driven shaft bearings4016a,4016b,4016c, and4016drotatably support driven shafts4010a,4010b,4010c, and4010d(only4010aand4010bare shown inFIG.33), respectively.

Pulleys4009a,4009b,4009c, and4009dare attached to one end of the driven shafts4010a,4010b,4010c, and4010d, respectively. Second pulleys4007aand4007bare attached to one end of the drive shaft4005adjacent to the pulley4006and to the other end of drive shaft4005. Across the second pulley4007a, the pulley4009aattached to the driven shaft4010aand the pulley4009cattached to the driven shaft4010c, and across the second pulley4007b, the pulley4009battached to the driven shaft4010band the pulley4009dattached to the driven shaft4010d, endless belts4008aand4008bare tacked, respectively. Therefore, when the drive shaft4005rotates, power is transmitted to the driven shafts4010aand4010cvia the second endless belt4008a, and as a result, the driven shafts4010aand4010crotate. The power from the drive shaft4005is also transmitted to the driven shafts4010band4010dvia the second endless belt4008b, and as a result, the driven shafts4010band4010dalso rotate.

Rollers4011a,4011b,4011c, and4011dare attached to the other ends of the driven shafts4010a,4010b,4010c, and4010d, respectively. One end4110aof a rotary shaft of the rotating body4100is placed on the rollers4011aand4011c, and the other end4110bof the rotary shaft of the rotating body4100is placed on the rollers4011band4011d, respectively. The rotating body4100rotates in accordance with rotation of these rollers4011a,4011b,4011c, and4011d. That is, the rotating body4100can be rotated while utilizing regenerative energy by driving the electric actuator100.

A keyway4102is formed at the other end4110bof the rotating body4100. A sensor S for detecting the keyway4102is further disposed on the balance measurement device4000.

Furthermore, as shown inFIGS.33and34, vibration pickups VDL and VDR are attached between the first side wall4013aof the base4013and the table4015. The rotating body4100, which is a crankshaft with dynamic imbalance, vibrates as it rotates. In the balance measurement device of the present embodiment, the vibration of the rotating body4100(crankshaft) is transmitted to the table4015via the rollers4011a,4011b,4011cand4011d, first and second table side walls4017a,4017b, and the like. The vibration pickups VDL and VDR detect the vibration transmitted from the rotating body4100(crankshaft) to the table4015. In other words, the vibration pickups VDL and VDR detect fluctuations in the load applied by the rotating body4100(crankshaft) to the rollers4011a,4011b,4011cand4011d.

The vibration pickups VDL and VDR are acceleration sensors capable of measuring acceleration in two components (in the X-axis and Y-axis directions) perpendicular to the rotary shaft of the rotating body4100, respectively. The vibration pickup VDL is attached on the same XY plane as the first table side wall4017a, and the vibration pickup VDR is attached on the same XY plane as the second table side wall4017b.

Piezoelectric actuators VL and VR are attached between the second side wall4013bof the base4013and the table4015. The piezoelectric actuator VL is attached on the same XY plane as the first table side wall4017a, and the piezoelectric actuator VR is attached on the same XY plane as the second table side wall4017b. The piezoelectric actuators are members that can expand and contract according to the magnitude of the applied voltage to displace an object being in contact with the piezoelectric actuators, and thus the table4015can be freely vibrated by controlling signals to be input to the piezoelectric actuators VL and VR.

Fourteenth Embodiment

FIG.35is a perspective view of a collision simulation test device5000according to a fourteenth embodiment of the present disclosure. The collision simulation test device5000is a device that reproduces impacts that act on automobiles and the like (including railroad cars, aircraft, and ships), occupants, and equipment of the automobiles and the like, at the time of collision of the automobiles and the like. The collision simulation test device5000of the present embodiment can also be used as an impact test device for evaluating durability and reliability against impact by applying strong impact waves to products and parts.

The collision simulation test device5000includes a table5240that is used to resemble a frame of a vehicle of a car. A test piece, such as a seat with an occupant dummy on it or a high-voltage battery for an electric car, are to be attached on the table5240. When the table5240is driven at a set acceleration (e.g., an acceleration equivalent to an impact that acts on a frame of a vehicle during a crash), the test piece attached to the table5240is subjected to an impact similar to that of an actual crash. Damage on the test piece at this time (or damage predicted from measurement results by acceleration sensors or other devices attached to the test piece) is used to evaluate safety of occupants.

The collision simulation test device5000of the present embodiment is configured to allow the table5240to be driven in only one horizontal direction. As shown inFIG.35with coordinate axes, a movable direction of the table5240is defined as an X-axis direction, a horizontal direction perpendicular to the X-axis direction is defined as a Y-axis direction, and the vertical direction is defined as the Z-axis direction. The X-axis positive direction is referred to as forward, the X-axis negative direction is referred to as backward, the Y-axis negative direction is referred to as right, and the Y-axis positive direction is referred to as left, based on a travelling direction of a vehicle being simulated. The X-axis direction in which the table5240is driven is referred to as a “drive direction.” In a collision simulation test, a large acceleration is applied to the table5240in a direction opposite to the travelling direction of the vehicle (i.e., backward).

The collision simulation test device5000includes a test section5200that includes the table5240, a front drive section5300and a rear drive section5400that drive the table5240, four belt mechanisms5100(belt mechanisms5100a,5100b,5100cand5100d) that convert rotary motion generated by each of the drive sections5300and5400into translational motion in the X axis direction and transmit the motion to the table5240, and a control system (not shown).

The test section5200is disposed at the central portion of the collision simulation test device5000in the X-axis direction, and the front drive section5300and the rear drive section5400are disposed adjacent to the front and rear of the test section5200, respectively.

FIG.36is a perspective view showing a structure of the test section5200and the belt mechanism5100. For convenience of explanation, the table5240and a base block5210(described later), which are components of the test section5200, are omitted inFIG.36.

In addition to the table5240, the test section5200includes the base block5210(FIG.35), a frame5220attached on the base block5210, and a pair of linear guideways5230(hereinafter referred to as “linear guides5230”) attached on the frame5220. The pair of linear guides5230supports the table5240to be movable only in the X-axis direction (drive direction).

As shown inFIG.36, the frame5220has a pair of left and right half-frames (a right frame5220R and a left frame5220L) connected with a plurality of connecting bars5220C extending in the Y-axis direction. Since the right frame5220R and the left frame5220L have the same structure (strictly speaking, mirror image relationship), only the left frame5220L will be described in detail.

The left frame5220L has a mounting part5221and a rail support part5222each extending in the X-axis direction, and three connecting parts5223(5223a,5223b,5223c) extending in the Z-axis direction and that connect the mounting part5221and rail support part5222. As shown inFIG.35, a length of the mounting part5221is substantially equal to a length of the base block5210in the X-axis direction, and the mounting part5221is supported in its entire length by the base block5210. A rear end of the mounting part5221and a rear end of the rail support part5222are connected to each other by the connecting part5223a.

The rail support part5222is longer than the mounting part5221(i.e., longer than the base block5210), and a distal end of the rail support part5222protrudes forward of the base block5210and is located above the front drive section5300.

The linear guide5230includes a rail5231extending in the X-axis direction, and two carriages5232that travel on the rail5231via rolling elements. The rails5231of the pair of linear guides5230are fixed to upper surfaces of the rail support parts5222of the right frame5220R and the left frame5220L, respectively. A length of the rail5231is substantially equal to the length of the rail support part5222, and the entire length of the rail5231is supported by the rail support part5222. A plurality of attachment holes (screw holes) are provided on an upper surface of the carriage5232, and the table5240is provided with a plurality of through holes corresponding to the attachment holes of the carriage5232. The carriage5232is fastened to the table5240by fitting bolts (not shown) that are passed through respective through-holes of the table5240into respective attachment holes of the carriage5232. The table5240and the four carriages5232constitute a dolly (thread).

The table5240is provided with an attachment structure such as screw holes for attaching a seat or other test piece (not shown), so that the test piece can be directly attached to the table5240. Since this eliminates the need for a mounting plate or other component for attaching the test piece, a weight of a movable portion to which the impact is to be applied can be reduced, thereby enabling application of impacts to the test piece with high fidelity up to high frequency components.

As shown inFIG.36, each belt mechanism5100includes a toothed belt5120, a pair of toothed pulleys (a first pulley5140and a second pulley5160) around which the toothed belt5120is wound, and a pair of belt clamps5180for securing the toothed belt5120to the table5240.

Four toothed belts5120are arranged in parallel between the right frame5220R and the left frame5220L. Each of the toothed belts5120is secured to the table5240by the belt clamps5180at two points along its lengthwise direction, respectively.

As shown inFIG.35, the front drive section5300includes a base block5310, and four electric actuators5320(5320a,5320b,5320cand5320d) mounted on the base block5310. The rear drive section5400includes a base block5410, and four electric actuators5420(5420a,5420b,5420cand5420d) mounted on the base block5410. Each of the eight electric actuators has the same configuration as the electric actuator100according to the first embodiment, with slight differences in position and orientation of the installation, and length and spacing of components, but the basic configuration is the same. Basic configurations of the front drive section5300and the rear drive section5400are also in common.

A not-shown controller synchronously controls driving of servomotors of the electric actuators5320ato5320dand5420ato5420dbased on an input acceleration waveform, thereby providing acceleration to the table5240in accordance with the above acceleration waveform. In the present embodiment, the controller drives all the eight servomotors to rotate back and forth in the same phase. This allows acceleration to be given to the table5240by outputting unidirectional rotary motion from each electric actuator while utilizing regenerative energy.

The electric actuators according to the embodiments of the present disclosure can be used in place of various prime movers that output rotary motion (e.g., engines, electric motors, hydraulic motors, air motors, steam turbines and the like).

The electric actuators according to the embodiments of the present disclosure can be used as a prime mover not only for various electric cars such as electrically powered 2—, 3- or 4-wheeled vehicles or trucks, buses and tractors with 6 or more wheels, but also for railroad vehicles. That is, the electric actuators according to the embodiments of the present disclosure can be used as a prime mover of any vehicle. The electric actuators according to the embodiments of the present disclosure can also be used as a prime mover for aircraft (e.g., propeller-driven aircraft), helicopters and other aircraft, and ships. That is, the electric actuator according to the embodiment of the present disclosure can be used as a prime mover of any mobility vehicles.

The electric actuators according to the embodiments of the present disclosure can also be used as a prime mover for various industrial machinery such as construction machinery, agricultural machinery, woodworking machinery, working machines, forging machinery, injection molding machines, robots, and transportation machinery (e.g., cranes, elevators, and conveyors).

The electric actuators according to the embodiments of the present disclosure can also be used as a prime mover for various home appliances (washing machines, refrigerators, air conditioners, compressors and the like).

The electric actuators according to the embodiments of the present disclosure can also be used as a prime mover for driving a hydraulic pump or compressor.

The foregoing is a description of exemplary embodiments of the present disclosure. Embodiments of the present disclosure are not limited to those described above, and various variations are possible within the scope of the technical concept of the present disclosure. For example, appropriate combinations of the embodiments explicitly indicated by way of example in the specification and/or obvious embodiments are also included in the embodiments of the present disclosure.

In the drive unit100ddescribed above, the screw shaft41of the ball screw40is directly connected to the shaft11of the motor10, but the drive unit may be provided with a reduction gear, and the motor10and the ball screw40may be connected via the reduction gear.

The electric drive system90(electric power feeding system90S) (FIG.5) of the first embodiment may be provided with the plug291and the battery295eas in the fourth embodiment.

The plug291and the battery295emay be removed from the electric drive system290(electric power feeding system290S) (FIG.16) of the fourth embodiment, and the circuit breaker92may be directly connected to the primary power source91.

The circuit breaker92, the electromagnetic switch93, and/or the reactor94may be removed from the electric drive system290(electric power feeding system290S) (FIG.16) of the fourth embodiment and may be provided in the front stage (primary power source side) of the plug291.

In the electric drive system90(electric power feeding system90S) (FIG.5) of the first embodiment, an AC generator may be used as the primary power source91.

In the electric drive system290(electric power feeding system290S) (FIG.16) of the fourth embodiment or the electric drive system690(electric power feeding system690S) (FIG.26) of the eleventh embodiment, the battery295emay be removed, and the capacitor95cwith large capacitance may be used to take on the storage function of battery295c.

In the electric drive system290(electric power feeding system290S) (FIG.16) of the fourth embodiment, a configuration in which a plurality of inverters95bare provided for one servo amplifier295, and the inverters95bare connected to the motors10, respectively (i.e., a configuration in which the power regenerative converter95a, the capacitor95cand the direct current bus bar95darc shared by a plurality of motors10) is employed, but the present disclosure is not limited to this configuration. For example, the servo amplifier95of the first embodiment (FIG.5) may be provided for each motor10. In this case, for example, the wiring is branched at the rear of the reactor94, and the servo amplifier95is connected to each branch wiring. Alternatively, the reactor94may be provided for each servo amplifier95, the wiring may be branched at a stage after the electromagnetic switch93, and the reactor94and the servo amplifier95may be connected to each branch wiring.

The electric actuator100according to the first embodiment of the present disclosure described above includes a single drive unit100d, the electric actuator200according to the fourth embodiment of the present disclosure includes four drive units200d, and the electric actuator201according to the fifth embodiment of the present disclosure includes two drive units200d, but the present disclosure is not limited to these configurations, and any number of drive units can be provided in the electric actuator.

Each of the electric actuators100,200and201described above include a single crankshaft (crankshaft70, crankshaft270and crankshaft270a), but may be divided into a plurality of crankshafts. For example, if the electric actuator includes four drive units, the crankshaft may be divided into two, with two drive units100dconnected to each crankshaft. In this case, the divided plurality of crankshafts70are interconnected for example by a gear mechanism or a winding transmission mechanism such as belt mechanism so that the power of each crankshaft70is combined. By dividing the crankshafts70, more freedom in the arrangement of the plurality of drive units is provided, which enables downsizing.

The tire testing device2000according to the eleventh Embodiment, the multi-test device3000according to the twelfth Embodiment, the balance measurement device4000according to the thirteenth Embodiment, and the collision simulation test device5000according to the fourteenth Embodiment show examples in which the electric actuator100is used, but the electric actuator to be used in these devices is not limited to the electric actuator100according to the first embodiment. For example, electric actuators with two cylinders or more, such as the electric actuator200and the electric actuator201, may be used.

In each of the above embodiments, the motor10is an AC servomotor, but another type of electric motor of which drive amount (rotation angle) can be controlled, such as a DC servomotor or stepping motor, may be used as the motor10.

In the above fourth and tenth embodiments, the configurations in which an electric power feeding system includes a generator are illustrated, but the generator may be provided not only to the electric power feeding systems of the fourth and tenth embodiment but also to the electric power feeding systems of the other embodiments.

In each of the above embodiments, the power regenerative converter95ais used that is capable of returning excess regenerative electric power from the servo amplifier95to the primary power source91side, but a converter without an electric power regenerative function for returning excess electric power to the primary power source91side may be used. When a converter without an electric power regenerative function is used, it is desirable to provide a device that stores excess electric power (e.g., a large-capacity capacitor or a large-capacity battery) in the servo amplifier95instead of providing a regenerative resistance that absorbs regenerative electric power in the servo amplifier95.

FIGS.37and38are diagrams showing variations of the electric power feeding system that supplies electric power to the electric actuator according to each of the embodiments. In each of the above embodiments, a system that converts electric power supplied from a primary power source to drive an electric motor is illustrated, but electric power to be supplied from a power source to the system is not limited to alternating current electric power. As shown inFIGS.37and38, the motor10can be driven by supplying direct current electric power supplied from a battery791to an inverter via a converter. In this case, the regenerative electric power is stored in the battery791instead of being output to the primary power source.

An electric power feeding system790S (electric drive system790) shown inFIG.37includes a bidirectional DCDC converter795aas the converter. First, a charger792is connected to the battery791, and the battery791is charged by the electric power supplied via the charger792from the plug291plugged into an outlet (not shown) of a primary power source. Next, the battery791is connected to a servo amplifier795, and electric power from the battery791is supplied to inverter95bvia the bidirectional DCDC converter795ato drive the motor10, and regenerative electric power from the inverter95bis output to the battery791via the bidirectional DCDC converter795a.

An electric power feeding system890S (electric drive system890) shown inFIG.38includes a bidirectional DCAC converter895aupstream of the power regenerative converter95a. First, the charger792is connected to the battery791, and the battery791is charged by the electric power supplied via the charger792from a plug291athat is plugged into a primary electric power outlet (not shown). Next, the battery791is connected to a servo amplifier895, and electric power from the battery791is supplied to the inverter95bvia the bidirectional DCAC converter895aand the power regenerative converter95ato drive the motor10, and regenerative electric power from the inverter95bis output via the power regenerative converter95aand the bidirectional DCAC converter895ato the battery791. The power regenerative converter95aand the bidirectional DCAC converter895aare connected to a plug291b. Electric power from the plug291bwhich is plugged into a primary electric power outlet (not shown) is supplied to the inverter95bvia the power regenerative converter95a, and this electric power can also drive motor10. The electric power supplied from plug291bis also supplied to the battery791via the bidirectional DCAC converter895a, and this electric power can be used to charge the battery791.

In each of the above embodiments, electric power was regenerated from the motor10to the primary power source via the inverter95band the power regenerative converter95a, but the electric power may be regenerated from the motor10to the primary power source without going through the inverter95band power regenerative converter95a.

Hereinabove, the illustrative embodiments according to aspects of the present disclosure have been described. The present disclosure can be practiced by employing conventional materials, methodology and equipment. Accordingly, the details of such materials, equipment and methodology are not set forth herein in detail. In the previous descriptions, numerous specific details are set forth, such as specific materials, structures, chemicals, processes, etc., in order to provide a thorough understanding of the present disclosure. However, it should be recognized that the present disclosure can be practiced without reapportioning to the details specifically set forth. In other instances, well known processing structures have not been described in detail, in order not to unnecessarily obscure the present disclosure.

Only exemplary illustrative embodiments of the present disclosure and but a few examples of their versatility are shown and described in the present disclosure. It is to be understood that the present disclosure is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.

This specification also discloses the followings.

An electric actuator including:an electric motor;a drive device that supplies driving electric power to the electric motor;a controller capable of controlling the drive device so that the electric motor outputs repeating reciprocating rotary motion; anda motion converter that converts the reciprocating rotary motion into a unidirectional rotary motion,

wherein the drive device includes:a converter that converts alternating current electric power supplied from a power source into direct current electric power; andan inverter that generates driving electric power from the direct current electric power.

The electric actuator according to Additional Note 1,

wherein the motion converter includes:a first disk part connected to a shaft of the electric motor;a first pin eccentrically attached to the first disk part;a second disk part connected to an output shaft of the motion converter;a second pin eccentrically attached to the second disk part; anda connecting rod that connects the first disk part to the second disk part, wherein:an end of the connecting rod is rotatably coupled to the first pin, andthe other end of the connecting rod is rotatably coupled to the second pin.

The electric actuator according to Additional Note 1,

wherein the motion converter includes:a first motion converter that converts the reciprocating rotary motion into reciprocating linear motion; anda second motion converter that converts the reciprocating linear motion into the unidirectional rotary motion.

An electric actuator including:an electric motor;a first motion converter that converts rotary motion into linear motion;a second motion converter that converts the linear motion into a rotary motion;a drive device that supplies driving electric power to the electric motor; anda controller that controls the drive device, wherein the drive device includes:a converter that converts alternating current electric power supplied from a power source into direct current electric power; andan inverter that generates driving electric power from the direct current electric power, wherein the controller controls the electric motor to be driven to repeatedly rotate back and forth.

The electric actuator according to Additional Note 4,

wherein the first motion converter is a ball screw and includes:a linear motion part that is fixed to a nut of a feed screw and moves linearly together with the nut, the linear motion part including a first pin;a crankshaft including an eccentric crank pin; anda connecting rod rotatably connected to the first pin and the crank pin.

The electric actuator according to any one of Additional Note 1 to Additional Note 5, wherein the drive device includes:a direct current bus bar consisting of a pair of conductors that connects the converter to the inverter; and

a capacitor that connects the pair of conductors.

The electric actuator according to any one of Additional Note 1 to Additional Note 5 including a plurality of the electric motors,

wherein the drive device includes:a system of direct current bus bar consisting of a pair of conductors connected to the converter;a plurality of the inverters connected to the system of direct current bus bar; anda capacitor that connects the pair of conductors.

The electric actuator according to any one of Additional Note 1 to Additional Note 7,

wherein the converter is a PWM converter.

The electric actuator according to any one of Additional Note 1 to Additional Note 8, wherein the controller controls the electric motor to be driven to repeatedly rotate back and forth at a frequency of 3 Hz or more.

The electric actuator according to any one of Additional Note 1 to Additional Note 9 including a generator that generates electric power using power generated by the electric motor.

The electric actuator according to Additional Note 10 including an inverter that converts the electric power generated by the generator into alternating current of the same quality as a system electric power and supplies the alternating current to a power source side.

An electric car including:a wheel; andthe electric actuator according to any one of Additional Note 1 to Additional Note 11 that outputs rotary motion for driving the wheel.

A railroad vehicle including:a wheel; andthe electric actuator according to any one of Additional Note 1 to Additional Note 11 that outputs rotary motion for driving the wheel.

The railroad vehicle according to Additional Note 13 including a dolly including:the wheel; andthe electric actuator.

An electric actuator including:an electric motor that repeats forward rotation and reverse rotation at a desired frequency; anda motion converter that converts forward and reverse rotary motions output by the electric motor into unidirectional rotary motion.

The electric actuator according to Additional Note 21 further including a drive device that supply electric power supplied from a power source to the electric motor, wherein the drive device includes a power regenerative converter that regenerates, among electric power regenerated from the electric motor while repeating the forward rotation and reverse rotation, electric power that has not been consumed in acceleration of the electric motor to the power source.

The electric actuator according to Additional Note 22, wherein the power regenerative converter outputs, to the power source, electric power regenerated from the electric motor at deceleration phases of the electric motor in the forward rotation and the reverse rotation.

The electric actuator according to Additional Note 22, wherein:

the power source consists of an alternating current power source, and

the power regenerative converter consists of a bidirectional ACDC converter.

The electric actuator according to Additional Note 22, wherein:

the power source consists of a direct current power source, and

the power regenerative converter consists of a bidirectional DCDC converter.

The electric actuator according to any one of Additional Note 22 to Additional Note 25, wherein the drive device further includes a capacitor that accumulates, among the electric power regenerated from the electric motor while repeating the forward rotation and reverse rotation, electric power that has not been consumed in acceleration of the electric motor.

The electric actuator according to Additional Note 21 further including a drive device that supplies electric power supplied from a power source to the electric motor, wherein the drive device includes a capacitor that accumulates, among electric power regenerated from the electric motor while repeating the forward rotation and reverse rotation, electric power that has not been consumed in acceleration of the electric motor.

The electric actuator according to any one of Additional Note 22 to Additional Note 27, wherein the electric motor repeats the forward rotation and the reverse rotation at a required frequency of 3 Hz or more.

The electric actuator according to any one of Additional Note 22 to Additional Note 28,

wherein the motion converter includes:a first motion converter that converts the forward and reverse rotary motions into a reciprocating linear motion; anda second motion converter that converts the reciprocating linear motion into a unidirectional rotary motion.

The electric actuator according to Additional Note 29 further including:a plurality of electric motors including said electric motor;a plurality of first motion converters, including said first motion converter, that convert the forward and reverse rotary motions output by each of the plurality of electric motors into the reciprocating linear motion; anda plurality of second motion converters, including said second motion converter, that convert the reciprocating linear motion converted by each of the plurality of first motion converters into the unidirectional rotary motion,

wherein the plurality of second motion converters share an output shaft for the unidirectional rotary motion.

The electric actuator according to Additional Note 29, wherein the motion converter includes:a ball screw;a linear motion part fixed to a nut of the ball screw and that moves linearly together with the nut;a rotating body that is freely rotatable around a rotation axis; anda connecting rod rotatably connected to a portion of the rotating body that is eccentric with respect to the rotation axis and to the linear motion part.

The electric actuator according to Additional Note 31 wherein:

the rotating body is a crankshaft, and the connecting rod is rotatably connected to a crank pin of the crankshaft.

The electric actuator according to Additional Note 31 wherein:

the rotating body is a spindle, and the connecting rod is rotatably connected to a projection formed to the spindle at a position eccentric with respect to the rotation axis.

The electric actuator according to any one of Additional Note 31 to Additional Note 33 further including a controller that controls the drive device, wherein the controller controls the drive device to switch rotation of the electric motor between the forward rotation and the reverse rotation while avoiding timings at which the linear motion part reaches dead points where no rotational force is generated to the rotating body by the movement of the linear motion part.

The electric actuator according to any one of Additional Note 31 to Additional Note 33 further including a controller that controls the drive device, wherein the controller controls the drive device so that torque of the electric motor is limited at least at timings at which the linear motion part reaches dead points where no rotational force is generated to the rotating body by the movement of the linear motion part.

The electric actuator according to any one of Additional Note 31 to Additional Note 38, wherein the motion converter includes:a first disk part connected to a shaft of the electric motor and freely rotatable about a first rotation axis;a second disk part connected to an output shaft of the motion converter and freely rotatable about a second rotation axis; anda connecting rod rotatable connected to a portion of the first disk part eccentric with respect to the first rotation axis and to a portion of the second disk part eccentric with respect to the second rotation axis.

An electric mobility vehicle including the electric actuator according to any one of Additional Note 31 to Additional Note 36.