Patent Description:
A power transmission component, such as a clutch or a propeller shaft, receives varying torque about a rotation axis in a state where the power transmission component rotates at a high speed. In order to accurately evaluate the fatigue resistance of such a component, a rotational torsion test where torque (a torsion load) is applied to a test piece about the rotation axis while rotating the test piece is performed.

<CIT> discloses a rotational torsion tester including a hydraulic actuator <NUM> which applies torque to a test piece <NUM>, and an AC motor <NUM> which rotates the hydraulic actuator <NUM> and the test piece <NUM> in a synchronized manner. The AC motor <NUM> rotates a main body of the hydraulic actuator <NUM>, and rotates an output shaft of the test piece <NUM> coaxially at the same speed as that of the main body of the hydraulic actuator <NUM>. An output shaft of the hydraulic actuator <NUM> is coupled to an input shaft of the test piece <NUM>, so that, by driving the AC motor <NUM> and the hydraulic actuator <NUM>, torque can be applied to the test piece <NUM> while rotating the test piece <NUM>. The torque applied to the test piece <NUM> is measured by a torque detector <NUM> provided between the output shaft <NUM> and the test piece <NUM>.

<CIT> discloses a rotational torsion tester having a stepped hollow cylindrical block with a cylindrically shaped shaft part at the left end and a cylindrically shaped shaft part <NUM> at the right end, both of which are rotatably supported by outer bearings between those shaft parts and parts of the base. The block is driven by the motor <NUM> via a driving belt <NUM>. The cylindrically shaped shaft part <NUM> at the right end is connected via a flexible coupling 7b to a further shaft having the right end 2b attached to a test piece <NUM>. The cylindrical block internally accommodates a hydraulic arrangement for providing a rotational torque between the axis of rotation of the cylindrical block and has an output shaft 3a which extends through the cylindrically shaped shaft part <NUM> at the right end of the cylindrical block and is connected via another flexible coupling 7a to a further shaft having the right end 3b attached to a test piece <NUM>. The output shaft 3a is not rotatably supported.

The tester described in <CIT> is configured such that the test piece <NUM> and an attachment flange for attaching the test piece <NUM> are supported by the tester via the torque detector <NUM>. Therefore, to the torque detector <NUM>, a torsion load to be measured as well as a bending load caused by gravity and a centrifugal force of the test piece <NUM> and the attachment flange are applied. As a result, it becomes difficult to adequately accurately measure the torque applied to the test piece <NUM> during the testing.

According to an embodiment of the invention, there is provided load applying unit configured to apply a predetermined torque to a test piece while rotating together with the test piece, the load applying unit comprising: a stepped cylindrical casing having a cylindrically shaped motor accommodation unit, a first cylindrically shaped shaft part at one end of the stepped cylindrical casing for rotatable support by a first bearing unit, and a second cylindrically shaped shaft part at the other end of the stepped cylindrical casing for rotatable support by a second bearing unit; a shaft part to which a slip ring of a slip ring part is attached; characterized by a pair of bearings provided on an inner circumferential surface of the first cylindrically shaped shaft part; an electric servo motor fixedly accommodated in the cylindrical casing and having a drive shaft; and a joint shaft having one end which is connected to the electric servo motor drive shaft and the other end which protrudes outward from the cylindrical casing and is rotatably supported by the pair of bearings.

Further features of the invention can be found in the subsidiary claims.

With this configuration, a bending load applied to the first drive shaft is received by the pair of second bearings. Therefore, almost no bending load is transmitted to the part of the first drive shaft disposed between the second bearings, and it is possible to prevent the bending load from affecting the detection result of the torque sensor. Furthermore, according to the above described configuration, the effect of the bending load caused on the load applying unit side as well as the effect of the bending load caused on the test piece side can also be suppressed.

The load applying unit may comprise: an electric motor that drives the first drive shaft; and a drive amount detection unit configured to detect a drive amount of the electric motor.

The rotational torsion tester may further comprise: a drive power supply unit that is disposed outside the load applying unit and is configured to supply driving power to the electric motor; a drive power transmission line configured to transmit the driving power from the drive power supply unit to the electric motor; a torque signal processing unit that is disposed outside the load applying unit and is configured to process a torque signal outputted by the torque sensor; and a torque signal transmission line configured to transmit the torque signal from the torque sensor to the torque signal processing unit. The drive power transmission line may comprise: an outer drive power transmission line disposed outside the load applying unit; an internal drive power transmission line that is disposed in an inside of the load applying unit and is configured to rotate together with the load applying unit; and a first slip ring part that connects the outer drive power transmission line with the internal drive power transmission line. The torque signal transmission line may comprise: an outer torque signal transmission line disposed outside the load applying unit; an internal torque signal transmission line that is disposed in an inside of the load applying unit and is configured to rotate together with the load applying unit; and a second slip ring part that connects the outer torque signal transmission line with the internal torque signal transmission line. The second slip ring part may be disposed to be away from the first slip ring part.

With this configuration, it becomes possible to supply the driving current to the rotating electric motor, and thereby a rotational torsion tester employing an electric motor can be realized. By employing an electric motor, the need for a hydraulic pressure supply device which requires a wide installation space can be eliminated, and a user is released from a troublesome maintenance work for a hydraulic system. Furthermore, since leakage of hydraulic oil is solved, a suitable working environment can be maintained. In addition, the drive power transmission line and the torque signal transmission line are completely separated by using individual slip rings, electromagnetic interference from the power transmission line, through which a large current flows, to the torque signal transmission line through which a weak current flows can be reduced. As a result, deterioration of the detection accuracy of the torsional load can be suppressed.

The at least one first bearing may be disposed between the first slip ring part and the second slip ring part.

With this configuration, electromagnetic noise caused in the first slip ring part through which a large current flows is blocked by the first bearing. Therefore, the electromagnetic noise becomes hard to be mixed into the torque signal transmission line via the second slip ring part, and thereby deterioration of the detection accuracy of the torsional load can be prevented.

A narrowed part formed to have a decreased diameter may be formed at the part at which the first drive shaft is situated in the shaft part, and the torque sensor may include a strain gauge adhered to the narrowed part to detect the torsional load.

With this configuration, the torque sensor can be realized in a compact size thanks to the simple configuration where the strain gauge is directly adhered to the second drive shaft. Furthermore, by adhering the strain gauge to the narrowed part, it becomes possible to accommodate the torque sensor in the shaft part without interference with the shaft part. Furthermore, the torque sensor having a high degree of detection sensitivity can be realized thanks to the configuration where the strain gauge is adhered to the narrowed part.

The shaft part may have a groove extending in the axial direction from the narrowed part. The internal torque signal transmission line may be formed to pass through the groove from the narrowed part, and may be connected to a ring-shaped electrode of the second slip ring part.

With this configuration, making and installation of the torque sensor can be performed easily.

The rotational torsion tester may further comprise a drive amount signal transmission line configured to transmit a signal outputted by the drive amount detection unit to the drive power supply unit. The drive amount signal transmission line may comprise: an outer drive amount signal transmission line disposed outside the load applying unit; an internal drive amount signal transmission line that is wired in an inside of the load applying unit and is configured to rotate together with the load applying unit; and a third slip ring part that is disposed to be away from the first slip ring part and is configured to connect the outer drive amount signal transmission line with the internal drive amount signal transmission line.

With this configuration, the electromagnetic interference between the drive power transmission line and the drive amount signal transmission line can be suppressed, and deterioration of the detection accuracy of the drive amount can be prevented.

The rotational torsion tester may further comprise a rotation number detection unit configured to detect a number of rotations of the load applying unit. The at least one first bearing may be disposed between the rotation number detection unit and the first slip ring part.

The rotation drive unit may comprise a second motor; and a drive force transmission unit configured to transmit a driving force of the second motor to the load applying unit and the second drive shaft. The drive force transmission unit comprises: a first drive force transmission unit configured to transmit the driving force of the second motor to the second drive shaft; and a second drive force transmission unit configured to transmit the driving force of the second motor to the load applying unit.

Each of the first drive force transmission unit and the second drive force transmission unit may comprise at least one of an endless belt mechanism, a chain mechanism and a gear mechanism.

Each of the first drive force transmission unit and the second drive force transmission unit may comprise the endless belt mechanism. The first drive force transmission unit may comprise: a third drive shaft that is disposed to be parallel with the predetermined rotation axis and is configured to be driven by the second motor; a first drive pulley fixed to be coaxial with the third drive shaft; a first driven pulley fixed to be coaxial with the load applying unit; and a first endless belt provided to extend between the first drive pulley and the first driven pulley. The second drive force transmission unit comprises: a fourth drive shaft that is coaxially coupled to the third drive shaft; a second drive pulley fixed to the fourth drive shaft; a second driven pulley fixed to the first drive shaft; and a second endless belt provided to extend between the second drive pulley and the second driven pulley.

The first driven pulley may be formed on an outer circumferential surface of the frame of the load applying unit.

With this configuration, a compact device size can be realized, for example, in comparison with a general case where the first drive pulley is attached to an end of the frame.

The rotational torsion tester may further comprise a reduction gear disposed in the load applying unit. The first driven pulley may be fixed to a reduction gear fixing plate to which the reduction gear is attached.

With this configuration, the first drive pulley and the reduction gear which receive a large varying load can be coupled to each other in a high degree of rigidity. Therefore, a degree of deformation of the load applying unit during the testing is small, and the torsional load can be applied with a high degree of accuracy.

The first drive shaft and the frame of the load applying unit may be connected to each other coaxially and integrally.

With this configuration, it becomes possible to drive the first drive shaft and the load applying unit with a common drive power transmission mechanism. Therefore, a rotational torsion device having a simple configuration can be realized.

The frame of the load applying unit may have a cylindrical part whose outer circumferential surface is formed in a cylindrical shape to be coaxially with the predetermined rotation axis. The rotational torsion tester may further comprise: a third drive shaft that is disposed to be parallel with the predetermined rotation axis and is configured to be driven by the second motor; a first drive pulley fixed to the third drive shaft; and a timing belt wound around the first drive pulley and the cylindrical part of the frame.

With this configuration, by using a part of the frame of the load applying unit as the driven pulley, the rotational torsion tester having a smaller number of components and configured in a compact size can be realized.

The above described rotational torsion tester may be a rotational torsion tester for measuring motion of a workpiece when torsion is applied to the workpiece in a rotational direction while rotating the workpiece, based on detection results of the torque sensor.

In another aspect of the invention, a drive motor is connected to a load applying unit, wherein the drive motor is configured to drive the cylindrical casing of the load applying unit to rotate.

Hereafter, a rotational torsion tester is described with reference to the accompanying drawings.

<FIG> is a side view of a rotational torsion tester <NUM> according to a first embodiment of the invention. The rotational torsion tester <NUM> is an apparatus for performing a rotational torsion test for a test piece <NUM> being a vehicle clutch, and is able to apply set fixed or varying torque to a portion between an input shaft and an output shaft of the test piece T1 (e.g., between a clutch cover and a clutch disk) while rotating the test piece T1. The rotational torsion tester <NUM> includes a stage <NUM> which supports each part of the rotational torsion tester <NUM>, a load applying unit <NUM> which applies predetermined torque to the test piece T1 while rotating together with the test piece T1, bearing units <NUM>, <NUM> and <NUM> which support the load applying unit <NUM> to be rotatable, slip ring parts <NUM> and <NUM> which electrically connect parts outside the load applying unit <NUM> with parts inside the load applying unit <NUM>, a rotary encoder <NUM> which detects the number of rotations of the load applying unit <NUM>, an inverter motor <NUM> which drives and rotates the load applying unit <NUM> at a set speed in a set direction, a drive pulley <NUM> and a drive belt (timing belt) <NUM>.

The stage <NUM> includes a lower base plate <NUM> and an upper base plate <NUM> arranged in the up and down direction to be parallel with each other, and a plurality of vertical support walls <NUM> which couples the lower base plate <NUM> with the upper base plate <NUM>. A plurality of vibration absorption mounts <NUM> is disposed on a lower surface of the lower base plate <NUM>, and the stage <NUM> is disposed on a flat floor F via the vibration absorption mounts <NUM>. On an upper surface of the lower base plate <NUM>, the inverter motor <NUM> is fixed. To an upper surface of the upper base plate <NUM>, the bearing units <NUM>, <NUM> and <NUM> and the rotary encoder <NUM> are attached.

<FIG> is a vertical cross section around the load applying unit <NUM> of the rotational torsion tester <NUM>. The load applying unit <NUM> includes a stepped cylindrical casing 100a, a servo motor <NUM> attached to the casing 100a, a reduction gear <NUM> and a joint shaft <NUM>, and a torque sensor <NUM>. The casing 100a includes a motor accommodation unit (a body section) <NUM>, a shaft part <NUM> rotatably supported by the bearing unit <NUM>, a shaft part <NUM> rotatably supported by the bearing unit <NUM>, and a shaft part <NUM> to which a slip ring <NUM> of the slip ring part <NUM> (<FIG>) is attached. Each of the motor accommodation unit <NUM> and the shaft parts <NUM>, <NUM> and <NUM> is a cylindrical member (or a stepped cylindrical part whose diameter changes in a staircase pattern) having a hollow part. The motor accommodation unit <NUM> is a component having the largest diameter and accommodates the servo motor <NUM> in the hollow part. The shaft part <NUM> is connected to one end of the motor accommodation unit <NUM> on a test piece T1 side, and the shaft part <NUM> is connected to the other end of the motor accommodation unit <NUM>. To an opposite side end of the shaft part <NUM> with respect to the motor accommodation unit <NUM>, the shaft part <NUM> is connected. The shaft part <NUM> is rotatably supported by the bearing unit <NUM> at a tip end thereof (a left end in <FIG>).

The servo motor <NUM> is fixed to the motor accommodation unit <NUM> with a plurality of fixing bolts <NUM>. A drive shaft <NUM> of the servo motor <NUM> is coupled to an input shaft of the reduction gear <NUM> via a coupling <NUM>. The joint shaft <NUM> is connected to an output shaft of the reduction gear <NUM>. The reduction gear <NUM> is provided with an attachment flange <NUM>, and is fixed to the casing 100a by fastening the motor accommodation unit <NUM> and the shaft part <NUM> with bolts (not shown) in a state where the attachment flange <NUM> is sandwiched between the motor accommodation unit <NUM> and the shaft part <NUM>.

The shaft part <NUM> which is a stepped cylindrical member has a pulley part <NUM> having a large diameter on the motor accommodation unit <NUM> side, and a main shaft part <NUM> rotatably supported by the bearing unit <NUM> on the test piece T1 side. As shown in <FIG>, the drive belt <NUM> is provided to extend between the outer circumferential surface of the pulley part <NUM> and the drive pulley <NUM> attached to a drive shaft <NUM> of the inverter motor <NUM>. A driving force of the inverter motor <NUM> is transmitted to the pulley part <NUM> through the drive belt <NUM> to rotate the load applying unit <NUM>. In the pulley part <NUM>, a joint part of the reduction gear <NUM> and the joint shaft <NUM> is accommodated. By utilizing, as a pulley, a portion at which the outer diameter needs to be increased to accommodate the joint part, a compact apparatus configuration can be realized without increasing the number of parts.

To a tip (a right end in <FIG>) of the main shaft part <NUM> of the shaft part <NUM>, the torque sensor <NUM> is attached. A surface (a right side surface in <FIG>) of the torque sensor <NUM> is formed as a seating face to which the input shaft (clutch cover) of the test piece T1 is attached, and the torque applied to the test piece T1 is detected by the torque sensor <NUM>.

On an inner circumferential surface of the main shaft part <NUM> of the shaft part <NUM>, bearings <NUM> and <NUM> are provided respectively near the both ends in the axial direction. The tip (a right end in <FIG>) of the joint shaft <NUM> protrudes outward while penetrating through the torque sensor <NUM>. The protruded part from the torque sensor <NUM> is fixed by being inserted into a shaft hole of a clutch disc (a clutch hub) being the output shaft of the test piece T1. That is, by rotating the joint shaft <NUM> with respect to the casing 100a of the load applying unit <NUM> through the servo motor <NUM>, set dynamic or static torque can be applied between the input shaft (clutch cover) of the test piece T1 fixed to the casing 100a and the output shaft (clutch disc) of the test piece T1 fixed to the joint shaft <NUM>.

As shown in <FIG>, near the end (a left end in <FIG>) of the shaft part <NUM>, the rotary encoder <NUM> for detecting the number of rotations of the load applying unit <NUM> is disposed.

To a central portion of the shaft part <NUM>, the slip ring <NUM> of the slip ring part <NUM> is attached. To the slip ring <NUM>, a power line 150W (<FIG>) which supplies a driving current to the servo motor <NUM> is connected. The power line extending from the servo motor <NUM> is connected to the slip ring <NUM> via the hollow parts formed in the shaft parts <NUM> and <NUM>.

The slip ring part <NUM> includes the slip ring <NUM>, a brush fixing member <NUM> and four brushes <NUM>. As described above, the slip ring <NUM> is attached to the shaft part <NUM> of the load applying unit <NUM>. The brushes <NUM> are fixed to the bearing unit <NUM> by the brush fixing member <NUM>. The slip ring <NUM> has four electrode rings 51y arranged to have constant intervals therebetween in the axial direction, and the brushes <NUM> are arranged to face the respective electrode rings 51r. The power line 150W of the servo motor <NUM> is conned to each electrode ring 51r, and each terminal of the brush is connected to a servo motor drive unit <NUM> (which is described later). That is, the power line 150W of the servo motor <NUM> is connected to the servo motor drive unit <NUM> via the slip ring part <NUM>. The slip ring part <NUM> guides the drive current of the servo motor <NUM> supplied by the servo motor drive unit <NUM>, to the inside of the rotating load applying unit <NUM>.

To the tip (the left end in <FIG>) of the shaft part <NUM>, a slip ring (not shown) of the slip ring part <NUM> is attached. To the slip ring of the slip ring part <NUM>, a communication line 150W' (<FIG>) extending from the servo motor <NUM> is connected. For example, a signal of a built-in rotary encoder (not shown) provided in the servo motor <NUM> is outputted to the outside via the slip ring part <NUM>. If a large current, such as a driving current for a large-size motor, flows through a slip ring, large electromagnetic noise tends to occur. Furthermore, the slip ring is susceptible to electromagnetic noise because the slip ring is not shielded adequately. Thanks to the above described configuration where the communication line <NUM>' through which a weak current flows and the power line 150W through which a large current flows are connected to the external wirings by using separate slip rings arranged to have a certain distance therebetween, nose can be effectively prevented from mixing into a communication signal. In this embodiment, the slip ring part <NUM> is provided on an opposite surface with respect to the slip ring part <NUM> side of the bearing unit <NUM>. As a result, the bearing unit <NUM> also provides advantageous effect that the slip ring part <NUM> is shielded from the electromagnetic noise being produced in the slip ring part <NUM>.

Next, a control system of the rotational torsion tester <NUM> is explained. <FIG> is a block diagram generally illustrating a configuration of the control system of the rotational torsion tester <NUM>. The rotational torsion tester <NUM> includes a control unit <NUM> which entirely controls the rotational torsion tester <NUM>, a setting unit <NUM> for setting various test conditions, a waveform generation unit <NUM> which calculates a waveform for the drive amount of the servo motor <NUM> based on the set test condition and outputs the waveform to the control unit <NUM>, the servo motor drive unit <NUM> which generates the drive current for the servo motor <NUM> based on control from the control unit <NUM>, an inverter motor drive unit <NUM> which generates the drive current for the inverter motor <NUM> based on the control by the control unit <NUM>, a torque measurement unit <NUM> which calculates the torque being applied to the test piece T1 based on the signal from the torque sensor <NUM>, and a rotation number calculation unit <NUM> which calculates the number of rotations of the load applying unit <NUM> based on the signal from the rotary encoder <NUM>.

The setting unit <NUM> includes a user input interface, such as a touch panel (not shown), a removable record media reading device, such as a CD-ROM drive, an external input interface, such as a GPIB (General Purpose Interface Bus) or a USB (Universal Serial Bus), and a network interface. The setting unit <NUM> makes settings for the test condition based on a user input received through the user input interface, data read from the removal record media, data inputted from an external device (i.e., a function generator) via the external input interface, and/or data obtained from a server via the network interface. The rotational torsion tester <NUM> according to the embodiment supports two types of control including displacement control where the torsion given to the test piece T1 is controlled based on a torsion angle applied to the test piece T1 (i.e., a drive amount of the servo motor <NUM> detected by the built-in rotary encoder provided in the servo motor <NUM>), and torque control where the torsion given to the test piece T1 is controlled based on the torque being applied to the test piece T1 (i.e., the torque detected buy the torque sensor <NUM>). It is possible to make settings, through the setting unit <NUM>, as to which of the control manners should be used.

Based on the setting value for the number of rotations of the test piece T1 obtained from the setting unit <NUM>, the control unit <NUM> instructs the inverter motor drive unit <NUM> to execute rotation driving for the inverter motor <NUM>. Furthermore, based on the waveform data of the drive amount of the servo motor <NUM> obtained from the waveform generation unit <NUM>, the control unit <NUM> instructs the servo motor drive unit <NUM> to execute driving of the servo motor <NUM>.

As shown in <FIG>, a measured value of the torque calculated by the torque measurement unit <NUM> based on the signal of the torque sensor <NUM> is transmitted to the control unit <NUM> and the waveform generation unit <NUM>. The signal of the built-in rotary encoder provided in the servo motor <NUM> is transmitted to the control unit <NUM>, the waveform generation unit <NUM> and the servo motor drive unit <NUM>. The waveform generation unit <NUM> calculates the measured value of the number revolutions of the servo motor <NUM> from the signal of the built-in rotary encoder which detects the rotation angle of the drive shaft <NUM> of the servo motor <NUM>. For the torque control, the waveform generation unit <NUM> compares the setting value of the torque with the measured value of the torque (for the displacement control, the drive amount of the servo motor), and executes feedback control for the setting value of the drive amount of the servo motor <NUM> transmitted to the control unit <NUM> so that the setting value and the measured value of the torque become equal to each other.

The measured value of the number of rotations of the load applying unit <NUM> calculated by the rotation number calculation unit <NUM> based on the signal of the rotary encoder <NUM> is transmitted to the control unit <NUM>. The control unit <NUM> compares the setting value and the measured value of the number of rotations of the load applying unit <NUM>, and executes feedback control for the frequency of the drive current transmitted to the inverter motor <NUM> so that the setting value and the measured value of the number of rotations become equal to each other.

The servo motor drive unit <NUM> compares a target value of the drive amount of the servo motor <NUM> with the drive amount detected by the built-in rotary encoder, and executes feedback control for the drive current transmitted to the servo motor <NUM> so that the drive amount approaches the target value.

The control unit <NUM> includes a hard disk drive (not shown) for storing test data, and records the measured values of the rotation speed of the test piece T1 and the torsion angle (the rotation angle of the servo motor <NUM>) and the torsion load applied to the test piece T1 in the hard disk drive. Change of each measured value over time is recorded throughout the time period from the start to end of the test. By the above described configuration of the first embodiment described above, the rotational torsion test is performed for the clutch of a vehicle being the test piece T1.

Hereafter, a rotational torsion tester <NUM> according to a second embodiment of the invention is described. The rotational torsion tester <NUM> is an apparatus for performing rotational torsion test for a propeller shaft for a vehicle being a test piece, and is able to apply set fixed or varying torque to a portion between an input shaft and an output shaft of the propeller shaft while rotating the propeller shaft. <FIG> is a plan view of the rotational torsion tester <NUM>, and <FIG> is a side view (a drawing viewed from the upper side in <FIG>) of the rotational torsion tester <NUM>. <FIG> is a vertical cross section around a load applying unit <NUM> described later. A control system of the rotational torsion tester <NUM> has substantially the same configuration as that of the first embodiment shown in <FIG>.

As shown in <FIG>, the rotational torsion tester <NUM> includes four bases <NUM>, <NUM>, <NUM> and <NUM> supporting each part of the rotational torsion tester <NUM>, the load applying unit <NUM> which applies predetermined torque to a portion between both ends of the test piece T2 while rotating together with the test piece T2, bearing units <NUM>, <NUM> and <NUM> which rotatably supports the load applying unit <NUM>, slip ring parts <NUM>, <NUM> and <NUM> which electrically connects the inside and the outside wirings of the load applying unit <NUM>, a rotary encoder <NUM> which detects the number of rotations of the load applying unit <NUM>, an inverter motor <NUM> which drives and rotates an end of the load applying unit <NUM> and the test piece T2 at a set rotation direction and the number of rotations, a drive force transmission unit <NUM> (a drive pulley <NUM>, a drive belt (timing belt) <NUM> and a driven pulley <NUM>) which transmits the driving force of the inverter motor <NUM> to the load applying unit <NUM>, and a drive force transmission unit <NUM> which transmits the driving force of the inverter motor <NUM> to one end of the test piece T1. The drive force transmission unit <NUM> includes a bearing unit <NUM>, a drive shaft <NUM>, a relay shaft <NUM>, a bearing unit <NUM>, a drive shaft <NUM>, a drive pulley <NUM>, a bearing unit <NUM>, a drive shaft <NUM>, a driven pulley <NUM>, a drive belt (timing belt) <NUM> and a work attachment unit <NUM>.

The bearing units <NUM>, <NUM> and <NUM>, the slip ring part <NUM>, the slip ring part <NUM>, the rotary encoder <NUM>, the inverter motor <NUM> and the drive pulley <NUM> provided in the rotational torsion tester <NUM> are the same as the bearing units <NUM>, <NUM> and <NUM>, the slip ring part <NUM>, the slip ring part <NUM>, the rotary encoder <NUM>, the inverter motor <NUM> and the drive pulley <NUM> provided in the rotational torsion tester <NUM> according to the first embodiment. The load applying unit <NUM> has the same configuration as that of the load applying unit <NUM> according to the first embodiment, excepting a shaft part <NUM>, a joint shaft <NUM>, a work attachment unit <NUM> and a slip ring part <NUM> which are described later. The drive belt <NUM> is different from the drive belt <NUM> according to the first embodiment in that the drive belt <NUM> is hooked to the driven pulley <NUM> on the driven side, but the other structures of the drive belt <NUM> are the same as those of the drive belt <NUM>. In the following, to element which are the same as or similar to those of the first embodiment, the same or similar reference numbers are assigned and explanation thereof are omitted, and the explanation focuses on difference in the configuration from the first embodiment.

The four bases <NUM>, <NUM>, <NUM> and <NUM> are placed on a flat floor F, and are fixed with fixing bolts (not shown). On the base <NUM>, the inverter motor <NUM> and the bearing unit <NUM> are fixed. On the base <NUM>, the bearing units <NUM>, <NUM> and <NUM> which support the load applying unit <NUM> and a support frame <NUM> for the slip ring part <NUM> are fixed. On the base <NUM>, the bearing unit <NUM> is fixed. On the base <NUM>, the bearing unit <NUM> is fixed. The bases <NUM> and <NUM> are movable in the axial directions of the bearing units <NUM> and <NUM>, respectively, depending on the length of the test piece T1, by loosening the fixing bolts.

The joint shaft <NUM> of the load applying unit <NUM> projects outward from the tip (the right end in <FIG>) of the shaft part <NUM>, and the work attachment unit (a flange joint) <NUM> is fixed to the tip (the right end in <FIG>) of the joint shaft <NUM>. To the projected part of the joint shaft <NUM> from the shaft part <NUM>, the slip ring <NUM> having a plurality of electrode rings is attached.

As shown in <FIG>, at a part of the joint shaft <NUM> included in the shaft part <NUM>, a ring-shaped narrowed part <NUM> formed such that the outer diameter thereof is narrowed is formed, and a strain gauge <NUM> is attached to a circumferential surface of the narrowed part <NUM>. The joint shaft <NUM> is a cylindrical member having a hollow part (not shown) passing through the center axis thereof, and, in the narrowed part, an insertion hole (not shown) communicating with the hollow part is formed. A lead (not shown) of the strain gauge <NUM> is inserted into the above described insertion hole and the hollow part formed in the joint shaft <NUM>, and is connected to each electrode ring of the slip ring <NUM>. It should be noted that, in place of the hollow part and the insertion hole, a wiring groove may be formed on the circumferential surface of the joint shaft <NUM> to extend from the narrowed part <NUM> to the slip ring <NUM>, and the lead of the stain gauge <NUM> may be wired to the sip ring <NUM> such that the lead passes through the wiring groove.

Under the slip ring <NUM>, a flange part <NUM> fixed to the support frame <NUM> is disposed. The flange part <NUM> includes a plurality of flanges disposed to face and contact the respective electrode rings of the slip ring <NUM>. The terminal of each flange is connected to a torque measurement unit <NUM> (which is described later) with a wire (not sown).

Hereafter, the drive force transmission unit <NUM> (<FIG>) is explained. The bearing units <NUM>, <NUM> and <NUM> rotatably support the drive shafts <NUM>, <NUM> and <NUM>, respectively. One end (the left end in <FIG>) of the drive shaft <NUM> is coupled to the drive shaft of the inverter motor <NUM> via the drive pulley <NUM>. One end (the left end in <FIG>) of the drive shaft <NUM> is coupled to the other end (the right end in <FIG>) of the drive shaft <NUM> via the relay shaft <NUM>. The drive pulley <NUM> is attached to the other end (the right end in <FIG>) of the drive shaft <NUM>, and the driven pulley <NUM> is attached to one end (the right end in <FIG>) of the drive shaft <NUM>. The drive belt <NUM> is provided to extend between the drive pulley <NUM> and the driven pulley <NUM>. The work attachment unit (flange joint) <NUM> for fixing one end of the test piece T2 is attached to the other end (the left end in <FIG>) of the drive shaft <NUM>.

The driving force of the inverter motor <NUM> is transmitted to the work attachment unit <NUM> via the above described drive force transmission unit <NUM> (i.e., the drive shaft <NUM>, the relay shaft <NUM>, the drive shaft <NUM>, the drive pulley <NUM>, the drive belt <NUM>, the driven pulley <NUM> and the drive shaft <NUM>), to rotate the work attachment unit <NUM> at the set number of rotations and in the set rotational direction. At the same time, the driving force of the inverter motor <NUM> is transmitted to the load applying unit <NUM> via the drive force transmission unit <NUM> (i.e., the drive pulley <NUM>, the drive belt <NUM> and the driven pulley <NUM>), to rotate the load applying unit <NUM> and the work attachment unit <NUM> in a synchronized manner (i.e., constantly at the same speed and in the same phase).

Hereafter, function control of the rotational torsion tester <NUM> according to the second embodiment is explained. The following is an example of the control of the function control of the rotation torsion tester <NUM> according to the second embodiment, and it is also possible to apply the function control described below to the rotational torsion tester <NUM> according to the first embodiment. <FIG> is a flowchart of a process executed by the rotational torsion tester <NUM>. When the rotational torsion tester <NUM> is started, an initialization process S1 is executed for each component. Then, setting of the test condition is made by the setting unit <NUM> (S2). Setting of the test condition is conducted by user input on an input screen (not shown). The test condition may be inputted by reading existing test condition data from a recording medium, such as a memory card, or from a server via a network. Alternatively, the test condition (e.g., a test waveform) may be inputted from an external device, such as a function generator.

Next, the control unit <NUM> judges whether an operation mode of the inputted test condition is "static torsional operation" or "dynamic torsional operation" (S3). The "static torsional operation" is an operation mode where torsion is given to the work in a state where the work is stationary without rotating, and is applied when a general torsion test is performed. The "dynamic torsional operation" is an operation mode where torsion is given to the work while the work is rotating, and is applied to the rotational torsion test. When the operation mode of the set test condition is the static torsional operation, a "torsional operation process" (S100) shown in <FIG> is executed. When the operation mode of the set test condition is the dynamic torsional operation, a "dynamic torsional operation process" (S200) shown in <FIG> is executed.

In the torsional operation process S100 (<FIG>), first a drive amount waveform calculation process S101 in which a waveform of the inputted test torque is converted into a waveform of the drive amount of the servo motor <NUM> is executed. The drive amount waveform calculation process S101 is executed by a waveform generation unit <NUM> which is able to execute a calculation process at a high speed. Next, the control unit <NUM> outputs a drive signal representing an indication value of the drive amount corresponding to each time based on the drive amount waveform calculated in the process S101, to the servo motor drive unit <NUM>, to drive the servo motor <NUM> (S102). Ten, the control unit <NUM> obtains the measured value of the torque given to the test piece T2 from the torque measurement unit <NUM> (S103). Next, the waveform generation unit <NUM> judges whether the measured value of the torque obtained in the process S103 has reached a set value (S104). When the measured value of the torque has not reached the set value (S104: NO), the waveform generation unit <NUM> corrects the drive amount waveform in a feedback manner (S105), and the control unit <NUM> outputs the drive signal again based on the new drive amount waveform to drive the servo motor <NUM> (S102). When the measured value of the torque has reached the set value (S104: YES), the control unit <NUM> judges whether the drive control has completed to the end of the drive waveform (S106). When the drive control has not completed to the end of the drive waveform, the process returns to S102 to continue the drive control. When the drive control has completed, the process S100 terminates.

The above described torque control is an example where the torque given to the test piece T1 is controlled; however, the rotational torsion tester <NUM> may execute displacement control where the torsion angle (displacement) given to the test piece T1 is controlled. When the displacement control is executed, the waveform of the test displacement (torsion angle) is converted into the waveform of the drive amount of the servo motor <NUM> in the drive amount waveform calculation process S101. Furthermore, the waveform generation unit <NUM> calculates the measured value of the torsion angle given to the test piece T1 from the signal of the built-in rotary encoder provided in the servo motor <NUM> in S103, and judges whether the measured value of the torsion angle reaches the set value in S104.

In the dynamic torsional operation process S200 (<FIG>), first the inverter motor <NUM> is driven so that the test piece T2 rotates at the set number of rotations (S201). Then, the measured value of the number of rotations of the load applying unit <NUM> rotated by the inverter motor <NUM> together with the test piece T2 is obtained from the rotation number calculation unit <NUM> (S202). Then, the control unit <NUM> judges whether the obtained measured value of the number of rotations of the load applying unit <NUM> has reached the set value (S203). When the measured value has not reached the set value (S203: NO), the drive power (frequency) of the inverter motor <NUM> is corrected (S204). When the measured value of the number of rotations of the load applying unit <NUM> has reached the set value (S203: YES), the process proceeds to S205. In S205, the control unit <NUM> judges whether the test condition requires applying of a pre-load (torque) Lp to the test pieces T2. The pre-load Lp means a DC component (static load) of the torque applied to the test piece T2. For example, for rotational torsion test for simulating a braking operation, the pre-load Lp in the reverse direction (minus) of the rotation direction by the inverter motor <NUM> is applied (<FIG>). For rotational torsion test simulating a traveling test at a constant acceleration, the pre-load Lp in the same direction (plus) as the rotation direction by the inverter motor <NUM> is applied (<FIG>).

When the pre-load Lp is applied (S205: YES), the drive amount corresponding to the pre-load Lp is assigned to the indication value, and the servo motor <NUM> is driven so that only the pre-load Lp is applied to the test piece T2 (S206). Then, the measured value of the torque given to the test piece T2 is obtained from the torque measurement unit <NUM> (S207), and the control unit <NUM> judges whether the measured value reaches the set value of the pre-load (S208). When the measured value of the torque has not reached the set value of the pre-load Lp (S208: NO), the control unit <NUM> corrects the indication value of the drive amount of the servo motor <NUM> (S209), and drives the servo motor <NUM> again based on the corrected indication value (S206).

The pre-load Lp changes the number of rotations of the inverter motor <NUM> because the pre-load Lp also places a load on the inverter motor <NUM>. For this reason, the control unit <NUM> obtains again the measured value of the number of rotations of the load applying unit <NUM> (S219), and judges whether the measured value is equal to the set number of rotations (S211). When the measured value of the number of rotations is not equal to the set value (S211: NO), the control unit <NUM> corrects the frequency of the drive power of the inverter motor <NUM> so that the difference with respect to the set value is cancelled (S212). When the frequency of the drive current of the inverter motor <NUM> is corrected and the number of rotations of the load applying unit <NUM> changes, the torque given to the test piece T2 also changes. Therefore, by detecting the torque again (S207), the control unit <NUM> judges whether the pre-load equal to the set value is properly applied (S208).

When it is judged that the measured value of the number of rotations of the load applying unit <NUM> obtained in S211 is equal to the set value (S211: YES), the control unit <NUM> stores the indication value being used for the drive instruction for the inverter motor <NUM> and the servo motor <NUM> in a memory (S213). Then, the process proceeds to the torsional operation process S100 in the state where the preload Lp is being applied.

For the test condition where the pre-load Lp is not applied (S205: NO), the process directly proceeds to the torsional operation process S100.

Furthermore, for the test condition where the pre-load Lp is applied, the test torque is divided into a DC component (static load) and an AC component (dynamic load), and the calculation for the drive amount waveform is executed only for the AC component. Then, a value defined by adding the drive amount which gives the AC component calculated in S101 to the drive amount necessary for applying the pre-load stored in S212 is set as the indication value for the servo motor <NUM>. For the drive control of the inverter motor <NUM>, the indication value stored in S212 is used.

The foregoing is the explanations about the exemplary embodiments of the invention. It should be noted that the present invention is not limited to the above described embodiments, and may be varied within the scope of the invention expressed in the claims.

In the above described embodiment, the driving force of the servo motor is amplified by the reduction gear; however, the reduction gear may be omitted as long as a servo motor capable of outputting an adequately large degree of torque is used. By thus omitting the reduction gear, a frictional loss can be reduced, and the moment of inertia of the driving part of the rotational torsion tester can be reduced. As a result, the reversed driving at a higher frequency can be realized.

In the above described embodiment, the timing belt is used to transmit the driving force between the rotation shafts arranged in parallel with each other; however, an endless belt of another type (e.g., a flat bet or a V belt) may be used. A driving force transmission mechanism (e.g., a chain mechanism or a gear mechanism) other than the endless belt may be used.

In the above described second embodiment, the driven pulley <NUM> is disposed on the work attachment part <NUM> side with respect to the bearing unit <NUM>. With this configuration, the interval between the driven pulleys <NUM> and the <NUM> can be shortened, and the drive transmission part can be realized in a compact size. In the second embodiment, the driven pulley <NUM> is disposed on the opposite side of the work attachment unit <NUM> with respect to the bearing unit <NUM>; however, the driven pulley <NUM> may be disposed on the work attachment unit <NUM> side with respect to the bearing unit <NUM>. Such a configuration also makes it possible to realize the compact driving force transmission unit. The driven pulley <NUM> may be disposed on the opposite side of the work attachment unit <NUM> with respect to the bearing unit <NUM>. By disposing the bearing unit <NUM> between the driven pulley <NUM> and the work attachment unit <NUM>, the vibration noise in directions other than the rotational direction from the drive force transmission unit <NUM> to the test piece T2 can be prevented, and therefore a more precise testing can be achieved.

In the above described embodiment, the control unit provides a command signal in a form of a digital code with the servo motor drive unit and the inverter motor drive unit; however, a command signal (e.g., an analog current signal, an analog voltage signal or a pulse signal) in another form may be given to each drive unit.

In the above described embodiment, driving of the servo motor is controlled by controlling the rotation angle (displacement) of the drive shaft of the servo motor or the torque given to the test piece; however, embodiments of the invention are not limited to such a configuration, and control in which another type of parameter (e.g., a rotation speed of the servo motor or the torsional speed of the test piece) is used as a target value is also included in the scope of the invention.

Claim 1:
A load applying unit (<NUM>, <NUM>) configured to apply a predetermined torque to a test piece (T1) while rotating together with the test piece (T1), the load applying unit comprising: -
a stepped cylindrical casing (100a, 1100a) having a cylindrically shaped motor accommodation unit (<NUM>, <NUM>), a first cylindrically shaped shaft part (<NUM>) at one end of the stepped cylindrical casing (100a, 1100a) for rotatable support by a first bearing unit (<NUM>, <NUM>), and a second cylindrically shaped shaft part (<NUM>) at the other end of the stepped cylindrical casing (100a, <NUM>) for rotatable support by a second bearing unit (<NUM>, <NUM>);
a shaft part (<NUM>) to which a slip ring (<NUM>) of a slip ring part (<NUM>, <NUM>, <NUM>, <NUM>) is attached; characterized by
a pair of bearings (<NUM>, <NUM>, <NUM>, <NUM>) provided on an inner circumferential surface of the first cylindrically shaped shaft part (<NUM>);
an electric servo motor (<NUM>, <NUM>) fixedly accommodated in the cylindrical casing (100a, 1100a) and having a drive shaft (<NUM>); and
a joint shaft (<NUM>) having one end which is connected to the electric servo motor drive shaft (<NUM>) and the other end which protrudes outward from the cylindrical casing (100a, 1100a) and is rotatably supported by the pair of bearings (<NUM>, <NUM>, <NUM>, <NUM>).