Differential planetary gear device, and differential planetary gear device starting device and starting method

A differential planetary gear apparatus has a single-pinion-type structure in which one planetary gear (3) is arranged in a radial direction and one or more planetary gears (3) are arranged in a circumferential direction in a region between a sun gear (1) and a ring gear (2), a drive source (4), a speed-change motive source (5), and a driven unit (6) are disposed at any one of an input side (I), an output side (O), and a speed-change side (T). The speed-change motive source (5) includes an electric motor.

TECHNICAL FIELD

The present invention relates to a differential planetary gear apparatus, and a starting apparatus and method for a differential planetary gear apparatus.

BACKGROUND ART

In a differential planetary gear apparatus, there has recently been a demand for using a motor, e.g., an inverter motor, as a rotational drive source for speed change in order to accurately control a transmission ratio.

As one of apparatuses which can meet such a demand, there has been known a differential planetary gear apparatus shown inFIG. 14, for example.

The differential planetary gear apparatus shown inFIG. 14comprises a sun gear Sg fixed to a tip end of an input shaft55connected to a drive source50, a plurality of first planetary gears (pinion gears) P1disposed radially outwardly of the sun gear Sg and meshing with this sun gear Sg, a plurality of second planetary gears (pinion gears) P2meshing with the first planetary gears P1, a ring gear Rg having internal teeth which mesh with the second planetary gears P2being internally contacted with the internal teeth, and an output shaft65connected to an edge portion of the ring gear Rg, each of which serves as a basic element of a transmission mechanism.

The differential planetary gear apparatus further comprises a hollow shaft Ca as the basic element. The input shaft55passes through the hollow shaft Ca in such a state that the input shaft55is rotatable relative to the hollow shaft Ca. The differential planetary gear apparatus further comprises a carrier C. This carrier C comprises an end surface Cb connected perpendicularly to an end of the hollow shaft Ca at the center thereof, and first and second support shafts J1and J2extending from the end surface Cb in parallel with the hollow shaft Ca and disposed around the hollow shaft Ca.

The plurality of first planetary gears P1are rotatably supported by the first support shafts J1, and the plurality of second planetary gears P2meshing with the first planetary gears P1are rotatably supported by the second support shafts J2.

A gear Cc is formed on a circumferential edge portion of the end surface Cb of the carrier C, and this gear Cc meshes with braking gears70and80. These braking gears70and80are connected to brake devices B1and B3via rotating shafts75and85, respectively.

The above-mentioned differential planetary gear apparatus shown inFIG. 14is of a double-pinion type.

However, this double-pinion-type differential planetary gear apparatus has a number of components, and hence the structure thereof becomes complicated and the radial size thereof becomes large. Further, because of mechanical unbalance in the radial direction, this type of differential planetary gear apparatus is unsuitable for a high-speed rotation. Furthermore, since a rotational speed is controlled by the brake devices B1and B3, its control accuracy is low.

In a case where a large-capacity constant-speed motor is used as the drive source of the above-mentioned differential planetary gear apparatus, in order to start such a constant speed motor, for example, a rotational speed of this drive source is required to be increased to nearly a rated rotational speed (e.g., a rotational speed within ±5% of the rated rotational speed) in some cases. In such cases, another starting drive means is required in order to increase the rotational speed of the drive source (e.g., the large-capacity constant-speed motor) to nearly a rated rotational speed (e.g., a rotational speed within ±5% of the rated rotational speed).

For example, in a case of starting a squirrel-cage induction motor, full voltage (i.e., full-voltage starting) is not preferable because starting current becomes high. Therefore, it is required to provide a reduced-voltage starter utilizing star delta, reactor, Kondorfer, or the like.

Providing such another starting drive means causes an increase in installation cost and other cost, and also causes a complicated structure.

Further, in a case of using a normal constant-speed motor as the starting drive means, if a constant rotational speed of the constant-speed motor, which serves as the starting drive means, is lower than the above-mentioned rotational speed near the rated rotational speed (e.g., the rotational speed within ±5% of the rated rotational speed), some sort of means is required for increasing the rotational speed. Otherwise, it is difficult to increase the rotational speed of the above-mentioned drive source to nearly the rated rotational speed.

DISCLOSURE OF INVENTION

The present invention has been made in view of the above drawbacks. It is therefore an object of the present invention to provide a differential planetary gear apparatus which eliminates a mechanical unbalance and has a high mechanical efficiency, and can cope with a high-speed operation. It is another object of the present invention to provide a starting apparatus and method for a differential planetary gear apparatus which can reduce a load on a drive source (e.g., a large-capacity constant-speed motor) during the starting.

A differential planetary gear apparatus (A, A-1, A-2) according to the present invention is characterized in that: the differential planetary gear apparatus has a single-pinion-type structure in which one planetary gear (3) is arranged in a radial direction (of a sun gear1and a ring gear2) and one or more planetary gears (3) are arranged in a circumferential direction (of the sun gear1and the ring gear2) in a region between the sun gear (1) and the ring gear (2); each of a drive source (e.g., a large-capacity constant-speed motor4or an internal combustion engine), a speed-change motive source (5), and a driven unit (e.g., a fluid machinery6or a turbo machinery) is disposed at any one of an input side (I), an output side (O), and a speed-change side (T); and the speed-change motive source (5) comprises an electric motor (a small-capacity variable-speed motor).

According to the differential planetary gear apparatus of the present invention having such a structure, a mechanical efficiency is high and a high-speed operation can be achieved because of a so-called “single pinion type” in which rotation is transmitted between the sun gear and the ring gear by the single planetary gear (3). Further, since the small-capacity variable-speed motor is used as the speed-change motive source, the speed change is performed accurately and smoothly.

A differential planetary gear apparatus (A-3, A-4, A-5) according to the present invention is characterized in that: a planetary gear (3) is disposed in a region between a sun gear (1) and a ring gear (2); each of a drive source (e.g., a large-capacity constant-speed motor4or an internal combustion engine), a speed-change motive source (5), and a driven unit (e.g., a fluid machinery6or a turbo machinery) is disposed at any one of an input side, an output side, and a speed-change side; the speed-change motive source comprises an electric motor; and supply of electric power (E) to the speed-change motive source (5) is stopped when the driven unit (6) is decelerated so that the speed-change motive source (5) generates electric power.

According to the differential planetary gear apparatus of the present invention having such a structure, the energy is generated and is thus effectively utilized during the deceleration, and the energy-saving apparatus which can meet the demands of the times can be achieved.

Further, the speed-change motive source. (5) can be used as a brake of the differential planetary gear apparatus by utilizing the generated energy in various ways.

In the differential planetary gear apparatus (A-3) of the present invention, it is preferable that the electric power generated by the speed-change motive source (5) is supplied to a resistance means (10).

According to the differential planetary gear apparatus of the present invention having such a structure, the resistance means can be used as a brake of the differential planetary gear apparatus, for example. Therefore, it is not necessary to incorporate another brake system for deceleration and stop of the apparatus, and it is also not necessary to put energy into the brake.

In the differential planetary gear apparatus (A-4) of the present invention, it is preferable that the electric power generated by the speed-change motive source (5) is supplied to a power regenerative converter (11) so as to return the generated electric power to a power source of the speed-change motive source (5).

In the differential planetary gear apparatus (A-5) of the present invention, it is preferable that the electric power generated by the speed-change motive source (5) is supplied to a storage means (12).

According to the differential planetary gear apparatus (A-4, A-5) of the present invention having such a structure, the following advantages can be obtained: When the apparatus is in non-acceleration state (i.e., a deceleration state and a constant-speed state), a surplus energy can be recovered as regenerative electric power or stored electric power, thus enabling an energy-saving operation at all times. While the surplus energy is recovered as the regenerative electric power or the stored electric power, the speed-change motive source (5) can be used as the brake of the differential planetary gear apparatus.

According to the present invention, there is provided a starting apparatus for a differential planetary gear apparatus (A-6, A-7, A-8) having a sun gear (1), a ring gear (2), and one or more planetary gears (3) and having a structure in which each of a drive source (e.g., a large-capacity constant-speed motor4), a speed-change motive source (5), and a driven unit (e.g., a fluid machinery6or a turbo machinery) is disposed at any one of an input side (I), an output side (O), and a speed-change side (T), the starting apparatus characterized in that: the drive source (4) is energized after a rotational speed of the drive source (4) is increased to nearly a rated rotational speed by a starting means; the starting means comprises the speed-change motive source (5), a speed-increasing means (13) provided at an output side of the speed-change motive source (5), and a rotation transmitting assembly for transmitting rotation from an output side of the speed-increasing means (13) to the drive source (4); and the rotation transmitting assembly serves as gears (1,3, g2, g1) and rotating shafts (23, Cj,21) of the differential planetary gear apparatus (A-6, A-7, A-8).

In the starting apparatus for the differential planetary gear apparatus of the present invention, it is preferable that a stop means (a brake14/40) is provided on a rotating shaft (an output shaft22) connected to the ring gear (2), and the stop means (14/40) is operated so as to lock the ring gear (2) while the rotational speed of the drive source (4) is increased by the starting means (5,13,23,1,3, Cj, g2, g1,21/35,37,23,1,3, Cj, g2, g1,21).

It is preferable that the speed-increasing means comprises a mechanical transmission (13).

According to the differential planetary gear apparatus of the present invention having such a structure, a desirable transmission ratio can be achieved by the rotational speed that is input from the speed-change motive source. Therefore, this differential planetary gear apparatus can effectively perform as a multi-speed transmission or a continuously variable transmission. In addition thereto, the rotational speed of the drive source (4) can be quickly increased to nearly the rated rotational speed by the starting means.

The starting means comprises the speed-change motive source (5), the speed-increasing means (13) provided at the output side of the speed-change motive source (5), and the rotation transmitting assembly for transmitting rotation from the output side of the speed-increasing means (13) to the drive source (4), and the rotation transmitting assembly serves as the gears (1,3, g2, g1) and the rotating shafts (23, Cj,2l) of the differential planetary gear apparatus (A-6, A-7, A-8) With this structure, it is not required to provided another starting means. Therefore, it is possible to suppress an increase in cost which would occur in the case of providing another starting means, and to prevent a complicated structure.

Further, in the case where the stop means (14) is provided, while the rotational speed of the drive source (4) is increased to nearly the rated rotational speed, a whole torque of the speed-change motive source (5) is put into the drive source (4), and hence the drive source (4) reaches near the rated rotational speed quickly. As a result, it is possible to prevent a load which would be produced when rotating the driven member (e.g., a rotary machine).

The speed-increasing means of the differential planetary gear apparatus comprises an inverter motor (35) and an inverter (37). The inverter may be of a type that is incorporated in the inverter motor.

According to the differential planetary gear apparatus of the present invention having such a structure, the starting of the drive source (4) is controlled by the inverter motor (35) and the inverter (37), and hence the drive source (4) can be started stably.

Further, the small-sized and space-saving apparatus as a whole can be achieved by using the inverter motor (35) and the inverter (37).

In the starting apparatus for the differential planetary gear apparatus according to the present invention, it is preferable that the differential planetary gear apparatus has a single-pinion-type structure in which one planetary gear (3) is arranged in a radial direction and one or more planetary gears (3) are arranged in a circumferential direction in a region between the sun gear (1) and the ring gear (2), and the speed-change motive source (5) comprises an electric motor (e.g., a variable-speed motor5).

Further, according to the present invention, there is provided a starting method for a differential planetary gear apparatus having a sun gear, a ring gear, and one or more planetary gears and having a structure in which each of a drive source, a speed-change motive source, and a driven unit is disposed at any one of an input side, an output side, and a speed-change side, the starting method characterized by: operating a brake so as to lock the ring gear when starting the drive source; starting an inverter and an inverter motor so as to rotate the drive source at a predetermined rotational speed; energizing the drive source to start the drive source at the predetermined rotational speed; and operating the drive source in a normal operation state.

It is preferable that the predetermined rotational speed is within a range of ±5% of a rated rotational speed of the drive source.

Since the motor (e.g., a variable-speed electric motor5) is used as the speed-change motive source (5), the speed change is performed accurately and smoothly.

Because the planetary gears (3) are of a single pinion type, a differential planetary gear assembly (G) has a high-mechanical efficiency and is suitable for a high-speed operation.

BEST MODE FOR CARRYING OUT THE INVENTION

First, a differential planetary gear apparatus according to a first embodiment will be described with reference toFIG. 1.

InFIG. 1, the differential planetary gear apparatus, which is indicated by a reference sign A as a whole, comprises an electric differential-planetary-type continuously variable transmission B having an input shaft21and an output shaft22, a drive unit4comprising a large-capacity constant-speed motor disposed at an input side I, i.e., connected to one end of the input shaft21via an input-side clutch31, and a fluid machinery6, such as a turbo machinery, disposed at an output side O, i.e., connected to one end of the output shaft22via an output-side clutch32.

The electric differential-planetary-type continuously variable transmission B comprises a differential planetary gear assembly G having an input shaft and an output shaft (i.e., the input shaft21and the output shaft22) and a speed-change drive shaft23, and a small-capacity variable-speed motor5for speed change connected to the speed-change drive shaft23.

The differential planetary gear assembly G comprises an input gear g1fixed to the other end of the input shaft21, a sun gear1fixed to the other end of the speed-change drive shaft23, a carrier C, a plurality of planetary gears3supported by the carrier C, and a ring gear2whose one end forms the output shaft22.

The carrier C comprises a hollow rotating shaft Cj, and an input-side gear g2fixed to one end (input side) of the rotating shaft Cj and disposed concentrically with the rotating shaft Cj. The input-side gear g2meshes with the input gear g1. The carrier C further comprises a plurality of planetary gear support shafts P disposed on the other end (output side) of the rotating shaft Cj at radially equal positions with respect to a center of the rotating shaft Cj and spaced from each other at equal intervals in a circumferential direction. These planetary gear support shafts P extend in parallel with the rotating shaft Cj.

The speed-change drive shaft23passes through a hollow portion of the rotating shaft Cj of the carrier C in such a state that the speed-change drive shaft23is rotatable relative to the rotating shaft Cj. The sun gear1fixed to the other end of the speed-change drive shaft23meshes with the planetary gears3.

The planetary gears3are rotatably supported by the planetary gear support shafts P of the carrier C, and mesh with the sun gear1. The planetary gears3are held in contact with an internal teeth portion2aof the ring gear2and mesh with the internal teeth portion2a.

Specifically, in view of only the radial direction of the ring gear2and the sun gear1, this structure is a so-called “single pinion type” in which the rotation is transmitted between the sun gear1and the ring gear2by the single planetary gear3.

Operation of the differential planetary gear apparatus according to the first embodiment will be described below.(1) At the Time of Starting(a) A Method in which the Speed-Change Variable-Speed Motor and the Drive Unit are Started at the Same Time

When starting the fluid machinery6, first, the drive unit4is operated. At the same time, the speed-change variable-speed motor5is started at a minimum speed. Accordingly, the carrier C driven by the drive unit4and the sun gear1directly connected to the speed-change variable-speed motor5are rotated simultaneously. The planetary gears3are rotated on the carrier C at a rotational speed given by multiplying a relative rotational speed between the carrier C and the sun gear1by a gear ratio of the planetary gear3to the sun gear1. The ring gear2directly connected to the fluid machinery6is started to be rotated at a rotational speed given by multiplying an absolute rotational speed of the planetary gear3by a gear ratio of the ring gear2to the planetary gear3.

When the drive unit4reaches the rated rotational speed, the speed-change variable-speed motor5is being rotated at a minimum speed, and hence the fluid machinery6is operated at a minimum speed.(b) A Method in which the Rotating Shaft of the Speed-Change Variable-Speed Motor is Locked

A brake (not shown) incorporated in the speed-change variable-speed motor5is operated to lock the rotating shaft (i.e., the sun gear1) of the speed-change variable-speed motor5. Subsequently, the drive unit4is operated. Accordingly, since the sun gear1directly connected to the speed-change variable-speed motor5is locked, the planetary gears3are rotated on the carrier C at a rotational speed given by multiplying the rotational speed of the carrier C, which is driven by the drive unit4, by a gear ratio of the planetary gear3to the sun gear1. The ring gear2directly connected to the fluid machinery6is started to be rotated at a rotational speed given by multiplying an absolute rotational speed of the planetary gears3by a gear ratio of the ring gear2to the planetary gear3.

After the drive unit4reaches the rated rotational speed, the brake of the speed-change variable-speed motor5is released, and the speed-change variable-speed motor5is started to be operated at a minimum speed. The planetary gears3are rotated on the carrier C at a rotational speed given by multiplying a relative rotational speed between the carrier C and the sun gear1by a gear ratio of the planetary gear3to the sun gear1. The ring gear2is rotated at a rotational speed given by multiplying an absolute rotational speed of the planetary gear3by a gear ratio of the ring gear2to the planetary gear3. Thus, the fluid machinery6is operated at a minimum speed.(2) At the Time of Operation

When the rotational speed of the speed-change variable-speed motor5is changed, the rotational speed of the sun gear1, which is directly connected to the speed-change variable-speed motor5, is also changed. Therefore, the rotational speed of the planetary gears3, which are rotated on the carrier C, is changed at a speed given by multiplying a relative rotational speed between the carrier C, which is driven by the drive unit4at a constant speed, and the sun gear1by a gear ratio of the planetary gear3to the sun gear1. As a result, the ring gear2, which is directly connected to the fluid machinery6, is rotated at a rotational speed given by multiplying an absolute rotational speed of the planetary gears3by a gear ratio of the ring gear2to the planetary gear3, and hence the rotational speed of the fluid machinery6is changed.

The first embodiment shown inFIG. 1has a high-mechanical efficiency and is suitable for a high-speed operation because of a single-pinion-type structure.

Further, in the first embodiment shown inFIG. 1, the rotational speed ωs of the sun gear1, which is directly connected to the speed-change variable-speed motor5, is changed by, for example, increasing or decreasing current for driving the speed-change variable-speed motor5. Therefore, a revolution speed ωc of the planetary gears3, which are supported by the carrier C and are revolved around the sun gear1while simultaneously meshing with the sun gear1and the ring gear2, can also be changed.

As a result, a ratio (transmission ratio) of a rotational speed of the ring gear2meshing with the planetary gears3, i.e., a rotational speed ωo of the output shaft22, to a rotational speed ωi of the input shaft21can also be changed.

In other words, because the variable-speed motor (variable-speed motor for speed change)5is used as a speed-change motive source, the speed change is performed accurately and smoothly.

Next, a second embodiment will be described with reference toFIG. 2.

InFIG. 2, a differential planetary gear apparatus, which is indicated by a reference sign A-1as a whole, comprises an electric differential-planetary-type-type continuously variable transmission B-1having an input shaft25(disposed at the right side in the drawing) and an output shaft26(disposed at the left side in the drawing), a drive unit4comprising a large-capacity constant-speed motor disposed at an input side I, i.e., connected to one end of the input shaft25via an input-side clutch31, and a fluid machinery6disposed at an output side O, i.e., connected to one end of the output shaft26via an output-side clutch32.

The electric differential-planetary-type-type continuously variable transmission B-1comprises a differential planetary gear assembly G-1having an input shaft and an output shaft (i.e., the input shaft25and the output shaft26) and a speed-change drive shaft23, and a speed-change variable-speed motor (a small-capacity variable-speed motor)5connected to the speed-change drive shaft23.

The differential planetary gear assembly G-1comprises a ring gear2-1whose one end forms the input shaft25, an output gear g11fixed to the other end of the output shaft26, a sun gear1-1fixed to the other end of the speed-change drive shaft23, a carrier C-1, and a plurality of planetary gears3-1supported by the carrier C-1.

The carrier C-1comprises a hollow rotating shaft Cj, and an output-side gear g21fixed to one end (output side) of the rotating shaft Cj and disposed concentrically with the rotating shaft Cj. The output-side gear g21meshes with the output gear g11. The carrier C-1further comprises a plurality of planetary gear support shafts P disposed on the other end (input side) of the rotating shaft Cj at radially equal positions from the rotating shaft Cj and spaced from each other at equal intervals in a circumferential direction. These planetary gear support shafts P extend in parallel with the rotating shaft Cj.

The speed-change drive shaft23passes through a hollow portion of the rotating shaft Cj of the carrier C-1in such a state that the speed-change drive shaft23is rotatable relative to the rotating shaft Cj. The sun gear1-1fixed to the other end of the speed-change drive shaft23meshes with the planetary gears3-1.

The planetary gears3-1are rotatably supported by the planetary gear support shafts P of the carrier C-1, and mesh with the sun gear1-1. The planetary gears3-1are held in contact with an internal teeth portion2aof the ring gear2-1and mesh with the internal teeth portion2a.

The second embodiment shown inFIG. 2has a high-mechanical efficiency and is suitable for a high-speed operation because the planetary gears3-1are of a single pinion type, as with the first embodiment shown inFIG. 1.

Further, in the second embodiment shown inFIG. 2, the rotational speed ωs of the sun gear1-1, which is directly connected to the speed-change variable-speed motor5, is changed by, for example, increasing or decreasing current for driving the speed-change variable-speed motor5. Therefore, a revolution speed of the planetary gears3-1which are supported by the carrier C-1and are revolved around the sun gear1-1while simultaneously meshing with the sun gear1-1and the ring gear2-1, i.e., a rotational speed ωc of the carrier C-1, can also be changed. Accordingly, a speed ratio (transmission ratio) of a rotational speed ωo of the output shaft26meshing with the carrier C-1to a rotational speed ωi of the input shaft25can also be changed.

In other words, because the variable-speed motor5is used as a speed-change motive source and the rotational speed is changed by the single-pinion-type differential planetary gears, the speed change is performed accurately and smoothly.

Next, a third embodiment will be described with reference toFIG. 3.

InFIG. 3, a differential planetary gear apparatus, which is indicated by a reference sign A-2as a whole, has a structure in which a speed-change gear7, such as a speed-increasing gear or a speed-decreasing gear, is added to the first embodiment shown inFIG. 1. This speed-change gear7is disposed on the output shaft22at a location between the ring gear2and the output-side clutch32.

According to the third embodiment shown inFIG. 3, the speed change can be performed in a wider speed range, compared with the first embodiment shown inFIG. 1.

FIG. 4is a block diagram showing a fourth embodiment of the present invention. As with the above-mentioned embodiment, the differential planetary gear G has three rotational elements: the sun gear, the planetary gears, and the ring gear. One of these rotational elements is connected to the drive unit4via an input shaft Si, one of the others is connected to the speed-change variable-speed motor (small-capacity variable-speed motor)5via a speed-change shaft Sv, and the remaining one is connected to the fluid machinery6via an output shaft So.

FIG. 5is a block diagram showing a fifth embodiment of the present invention. The drive unit4is connected to the input shaft Si of the differential planetary gear G via a speed-increasing or speed-decreasing gear V1. The speed-change variable-speed motor (small-capacity variable-speed motor)5is connected to the speed-change shaft Sv of the differential planetary gear G via a speed-increasing or speed-decreasing gear V2. Further, the output shaft So of the differential planetary gear G is connected to the fluid machinery6via a speed-increasing or speed-decreasing gear V3.

As shown inFIGS. 4 and 5, the present invention can be practiced in a variety of modifications. The rotational elements are selected according to the required transmission ratio, and whether or not to provide the speed-increasing or speed-decreasing gear is also decided according to the required transmission ratio.

Next, other embodiments will be described with reference toFIGS. 6 through 9.

In the embodiments shown inFIGS. 6 through 9, when the fluid machinery6is decelerated, supply of electric power for rotating the speed-change variable-speed motor (small-capacity variable-speed motor)5is stopped so that the speed-change variable-speed motor5generates electric power and acts as a brake simultaneously.

With reference toFIG. 6, there will be described an example in which the supply of electric power for rotating the speed-change variable-speed motor5is stopped when the fluid machinery6is decelerated so that the speed-change variable-speed motor5generates electric power and the generated electric power is absorbed by a braking resistor10.

InFIG. 6, a differential planetary gear apparatus, which is indicated by a reference sign A-3as a whole, has a structure in which the following components are added to the first embodiment shown inFIG. 1: A speed sensor S is provided on the output shaft22, and an inverter controller8is provided on a power line Ld connecting the speed-change variable-speed motor (small-capacity variable-speed motor)5and an external power E. The inverter controller8and the braking resistor10are connected by a power line Lf. Further, a control means (control panel)9is provided, and the speed sensor S, the control means9, and the inverter controller8are connected by input and output signal lines Li and Lo.

The drive unit4is operated at a constant speed. Therefore, in order to accelerate the fluid machinery6from a stopped state to a desired speed, or in order to maintain the rotational speed of the fluid machinery6, the speed-change variable-speed motor5is supplied with the electric power from the external power E so that the speed-change variable-speed motor5imparts a driving force (rotation) for speed change to the sun gear1of the differential planetary gear assembly G.

On the other hand, the speed-change variable-speed motor5is constructed so as to act as a power generator when the rotating force (driving force) is imparted from the speed-change drive shaft23.

Therefore, when the fluid machinery6is decelerated after reaching a certain speed (i.e., after a desired driving force is obtained), a resultant of the surplus driving force of the drive unit4and an inertial force of the fluid machinery acts so as to impart (return) a driving force to the speed-change variable-speed motor5via the sun gear1. Specifically, when the fluid machinery6is decelerated as described above, the supply of the electric power from the external power E to the speed-change variable-speed motor5is stopped and the speed-change variable-speed motor5generates the electric power.

In consideration of the above-mentioned function of the speed-change variable-speed motor5, the control means9decides whether the differential planetary gear apparatus A-3is decelerated or not based on the rotational speed of the output shaft22obtained by the speed sensor S. If the differential planetary gear apparatus A-3is decelerated, the control means9sends a control signal to the inverter controller8so that the supply of the electric power from the external power E to the speed-change variable-speed motor5is stopped and the electric power generated by the speed-change variable-speed motor5is supplied to the braking resistor10. At this time, the speed-change variable-speed motor5acts as a brake.

Next, a control process of the speed-change variable-speed motor5and a power circuit will be described with reference toFIGS. 9 and 6.

In step S1, the control means9reads the rotational speed signal of the output shaft22sent from the speed sensor S via the input signal line Li, and decides whether the electric differential-planetary-type-type continuously variable transmission B-3is decelerated or not in step S2.

If the electric differential-planetary-type-type continuously variable transmission B-3is not decelerated (NO in step S2), the control process proceeds to step S3in which the speed-change variable-speed motor5(expressed as SM inFIG. 9) is used as a motor, and then proceeds to step S4. If the electric differential-planetary-type-type continuously variable transmission B-3is decelerated (YES in step S2), the control process proceeds to step S5in which the inverter controller8stops the supply of the electric power from the external power E to the speed-change variable-speed motor5. Further, in this step S5, the inverter controller8switches a circuit so as to send the electric power generated by the speed-change variable-speed motor5to the braking resistor10. Subsequently, the control process proceeds to step S6.

In step S6, the speed-change variable-speed motor5acts as a power generator, and the generated electric power is sent to the braking resistor10where the generated electric power is converted into heat due to braking. Then, the control process proceeds to step S4.

In step S4, the inverter controller8decides whether or not to finish the control. If the inverter controller8decided not to finish the control (NO in step4), then the control process is returned to step S1. If the inverter controller8decided to finish the control (YES in step4), then the control is finished.

According to the embodiment having such a structure shown inFIGS. 6 and 9, the braking resistor can be used as a brake of the differential planetary gear apparatus. Therefore, it is not required to incorporate another brake system for decelerating and stopping the apparatus, and it is not required to put energy into the brake.

Another example shown inFIG. 7is different from the embodiment shown inFIGS. 6 and 9in that when the electric differential-planetary-type-type continuously variable transmission B-3is decelerated, the electric power generated by the speed-change variable-speed motor (small-capacity variable-speed motor)5is supplied to a power regenerative converter11instead of being supplied to the braking resistor10. The inverter controller8, the power regenerative converter11, and the external power E are connected by power lines Lb. The electric power generated by the speed-change variable-speed motor (small-capacity variable-speed motor)5is supplied to the power regenerative converter11, so that the generated power is returned to a power source of the speed-change variable-speed motor (small-capacity variable-speed motor)5. Other components and operations including a control process are substantially the same as the embodiment shown inFIGS. 6 and 9.

Another example shown inFIG. 8is different from the embodiment shown inFIGS. 6 and 9in that when the electric differential-planetary-type-type continuously variable transmission B-3is decelerated, the electric power generated by the speed-change variable-speed motor (small-capacity variable-speed motor)5is supplied to a storage battery12instead of being supplied to the braking resistor10. The inverter controller8and the storage battery12are connected by a power line Lf. Other components and operations including a control process are substantially the same as the embodiment shown inFIGS. 6 and 9.

In the embodiments having the above-mentioned structure shown inFIGS. 7 through 9also, the surplus energy can be recovered as the regenerative electric power or the stored electric power during deceleration, thus enabling an energy-saving operation at all times. While the surplus energy is recovered as the regenerative electric power or the stored electric power, the speed-change variable-speed motor5acts as a brake unit.

In the embodiments shown inFIGS. 6 through 9, it is preferable that the differential planetary gear G has a single-pinion-type structure. However, the differential planetary gear G may have a double-pinion-type structure.

Advantages of the differential planetary gear apparatus according to the present invention are listed below.(a) Because the planetary gears are of single pinion type, a mechanical efficiency is high and a high-speed operation is achieved.(b) Because the variable-speed motor is used as a speed-change motive source, the speed change is performed accurately and smoothly.(c) Because the supply of the electric power for rotating the speed-change motive source is stopped so that the speed-change motive source generates electric power, there is no waste of energy and thus it is possible to achieve the energy-saving apparatus which can meet the demands of the times.(d) The resistance device can be used as a brake of the differential planetary gear apparatus. Therefore, it is not necessary to incorporate another brake system for deceleration and stop of the apparatus, and it is also not necessary to put energy into the brake.(e) When the output shaft of the electric differential-planetary-type-type continuously variable transmission is decelerated, the surplus energy can be recovered as the regenerative electric power or the stored electric power, thus enabling an energy-saving operation at all times.(f) Conventionally, in a case of performing a variable-speed operation, it is required to use a large-capacity inverter motor, a large-capacity fluid coupling, a hydraulic transmission such as a torque converter, or a mechanical transmission such as a belt chain CVT, which can cope with a load of the rotary machine, i.e., a driven machinery, such as a fluid machinery. Further, it is also required to use another variable-speed motive source. In contrast thereto, according to the present invention, the variable-speed motive source having a small capacity can be used, and hence the volume of the whole apparatus can be small, and the installation area can also be small.

Next, a sixth embodiment will be described with reference toFIG. 10.

InFIG. 10, a differential planetary gear apparatus, which is indicated by a reference sign A-6as a whole, comprises an electric differential-planetary-type continuously variable transmission B-4having an input shaft21and an output shaft22, a drive unit4comprising a large-capacity constant-speed motor connected to one end of an input side I (i.e., the input shaft21) via an input-side clutch31, and a rotary machine6A connected to one end of an output side O (i.e., the output shaft22) via an output-side clutch32. A turbo machinery is used as the rotary machine6A, for example.

The electric differential-planetary-type continuously variable transmission B-4comprises a differential planetary gear assembly G having an input shaft and an output shaft (i.e., the input shaft21and the output shaft22) and a speed-change drive shaft23, a direct-coupling/speed-increasing switchable gear13which can switch between a direct-coupling mode and a speed-increasing mode and is connected to the speed-change drive shaft23, a small-capacity variable-speed motor5for speed change connected to the direct-coupling/speed-increasing switchable gear13, and a brake14provide on the output shaft22.

The differential planetary gear assembly G comprises an input gear g1fixed to the other end of the input shaft21, a sun gear1provided on one end of the speed-change drive shaft23at the opposite side of the direct-coupling/speed-increasing switchable gear13, a carrier C, a plurality of planetary gears3supported by the carrier C, and a ring gear2whose one end forms the output shaft22.

The carrier C comprises a hollow rotating shaft Cj, and an input-side gear g2provided on one end (input side I) of the rotating shaft Cj and disposed concentrically with the rotating shaft Cj. The input-side gear g2meshes with the input gear g1. The carrier C further comprises a plurality of planetary gear support shafts P disposed on the other end (output side) of the rotating shaft Cj at radially equal positions with respect to a center of the rotating shaft Cj and spaced from each other at equal intervals in a circumferential direction. These planetary gear support shafts P extend in parallel with the rotating shaft Cj.

The speed-change drive shaft23passes through a hollow portion of the rotating shaft Cj of the carrier C in such a state that the speed-change drive shaft23is rotatable relative to the rotating shaft Cj. The sun gear1provided on the other end (output side O) of the speed-change drive shaft23meshes with the planetary gears3.

The planetary gears3are rotatably supported by the planetary gear support shafts P of the carrier C, and mesh with the sun gear1. The planetary gears3are held in contact with an internal teeth portion2aof the ring gear2and mesh with the internal teeth portion2a. Each of the planetary gears3is provided between the sun gear1and the ring gear2to form a single pinion type.

The brake14is operable manually or automatically. When the brake14is operated, the output shaft22, i.e., the ring gear2, is locked.

On the other hand, the direct-coupling/speed-increasing switchable gear13transmits the rotation of the speed-change variable-speed motor5to the sun gear1in a direct-coupling or speed-increasing manner, which is selectively switched by a non-illustrated switch means.

When starting the rotary machine, the brake14is operated, and substantially at the same time, the direct-coupling/speed-increasing switchable gear13is shifted to the speed-increasing side. Since the ring gear2is locked by operating the brake14, the planetary gears3, which mesh with the sun gear1and the ring gear2, are started to be rotated about their own axes by the rotation of the sun gear, which is rotated by the speed-change variable-speed motor5, and are also started to be revolved around the sun gear1. The revolution of the planetary gears3means the rotation of the carrier C, and thus rotates the input shaft21having the input gear g1which meshes with the input-side gear g2of the carrier C.

As described above, the input shaft21is connected to the drive unit4via the input-side clutch31. Therefore, the rotation of the speed-change variable-speed motor5, which can adjust its speed, is further increased by the direct-coupling/speed-increasing switchable gear13and is transmitted to the drive unit4. Accordingly, the rotational speed of the drive unit4can be quickly increased to nearly the rated rotational speed.

Further, since the ring gear2is locked and the rotary machine6A is in a non-operation state (a stopped state), the whole torque of the speed-change variable-speed motor5is effectively transmitted to the drive unit4.

In other words, it is possible to reduce a load which would be applied in case of rotating the rotary machine6A at the time of starting.

After the rotational speed of the drive unit4reaches the range of ±5% of the rated rotational speed, the brake14is released and the direct-coupling/speed-increasing switchable gear13is switched to the direct-coupling side. The rotational speed of the rotary machine6A serving as a driven machinery is gradually increased from a stopped state until its rotational speed reaches the normal-operation rotational speed.

For allowing the planetary gear assembly G to perform the speed change, the speed of the speed-change variable-speed motor5is changed (for example, current to be supplied to the motor is increased) so as to change the rotational speed ωs of the sun gear1. Therefore, the revolution speed ωc of the planetary gears3, which are supported by the carrier C and are revolved around the sun gear1while simultaneously meshing with the sun gear1and the ring gear2, can also be changed.

As a result, a ratio (transmission ratio) of a rotational speed of the ring gear2meshing with the planetary gears3, i.e., a rotational speed ωo of the output shaft22, to a rotational speed ωi of the input shaft21can also be changed.

In other words, because the variable-speed motor5is used as a speed-change motive source and the speed change is performed by the single-pinion-type differential planetary gear, the speed change is performed accurately and smoothly.

Next, a seventh embodiment will be described with reference toFIGS. 11 and 12.

InFIG. 11, a differential planetary gear apparatus, which is indicated by a reference sign A-7as a whole, is different from the sixth embodiment shown inFIG. 10in the following points: An inverter motor35and an inverter37are provided instead of the speed-change variable-speed motor5and the direct-coupling/speed-increasing switchable gear13, a speed sensor S is provided on the input shaft21, a control means9(expressed as ELU inFIG. 11) is connected to the speed sensor S by an input signal line Li, and the control means9and the inverter37are connected to each other by an output signal line Lo.

With reference toFIG. 12, and also toFIG. 11, a control process of the starting of the differential planetary gear apparatus A-7according to the seventh embodiment will be described below.

In step S, the control means9reads the rotational speed signal of the input shaft21sent from the speed sensor S via the input signal line Li, and decides whether or not the drive unit4is in a starting state in step S2.

If the drive unit4is in the starting state (YES in step S2), the control process proceeds to step S3in which the brake14is operated to lock the ring gear2, and then proceeds to step S4. If the drive unit4is not in the starting state (NO in step S2), the control process proceeds to step S6.

In step S4, the inverter37and the inverter motor35are started. The inverter motor35rotates the sun gear1via the speed-change drive shaft23. When the sun gear is rotated, the planetary gears3meshing with the sun gear1are rotated about their own axes and the carrier C is revolved. When the carrier C is rotated (i.e., revolved), the input-side gear g2of the carrier C rotates the input gear g1, thus rotating the drive unit4via the input shaft21and the input-side clutch31. The rotational speed of the drive unit4is gradually increased until it reaches the range of ±5% of the rated rotational speed of the drive unit4.

In subsequent step5, the drive unit4is energized so that the drive unit4itself is started within the range of ±5% of the rated rotational speed of the drive unit4, and the drive unit4is kept in a normal operation state (step S6).

In step S7, the control means9decides whether or not to finish the control. If the control means9decided not to finish the control (NO in step S7), then the control process proceeds to step S1. If the control means9decided to finish the control (YES in step S7), then the control is finished.

According to the seventh embodiment shown inFIGS. 11 and 12, the control means9, the inverter motor35, and the inverter37control the starting of the drive unit4, whereby the drive unit4can be started stably.

Further, the small-sized and space-saving apparatus as a whole can be achieved by using the inverter motor35and the inverter37.

Next, an eighth embodiment will be described with reference toFIG. 13.

InFIG. 13, a differential planetary gear apparatus, which is indicated by a reference sign A-8as a whole, is different from the sixth embodiment shown inFIG. 10in that a brake device40with speed-change mechanism is provided instead of the brake14on the output shaft. This brake device40with speed-change mechanism comprises a speed-increasing gear and/or a speed-decreasing gear, and a clutch for switching. Switching between “speed-changing and braking” is performed by a non-illustrated manual means or automatic means.

Since the brake14provided on the output shaft is replaced with the brake device40with speed-change mechanism having the speed-increasing gear and/or the speed-decreasing gear and the clutch for switching, the speed change can be performed in a wider speed range, compared with the sixth embodiment shown inFIG. 10.

The illustrated embodiments are only examples and do not limit the scope of the present invention. For example, the positional relationship between the drive unit4, the speed-change variable-speed motor5, and the rotary machine6A is not limited to the arrangement of the sixth embodiment shown inFIG. 10. As one example, the speed-change variable-speed motor5may be connected to the input shaft, and the drive unit4may be connected to the speed-change drive shaft, while the rotary machine6A is disposed at the output-shaft side as it is.

Each of the drive unit4, the speed-change variable-speed motor5, and the rotary machine6A can be connected to any one of three shafts of the differential planetary gear apparatus, and a total of six patterns of arrangement can be made. Which one of the six patterns of arrangement should be employed is decided according to several operating conditions (e.g., a desired transmission ratio).

Further, the control process illustrated in the seventh embodiment shown inFIGS. 11 and 12can be applied to the sixth embodiment and the eighth embodiment.

Advantages of the starting apparatus and method for the differential planetary gear apparatus according to the present invention are listed below.(a) The rotational speed of the drive source can be quickly increased to nearly the rated rotational speed by the speed-increasing means incorporated in the starting means.(b) While the drive source is increased to nearly the rated rotational speed, the whole torque of the speed-change motive source is put into the drive source because of the stop means. Therefore, it is possible to reduce a load which would be applied in case of rotating the driven machinery at the time of starting.(c) Because the inverter motor and the inverter control the starting of the drive source, the drive source can be started stably.(d) The small-sized and space-saving apparatus as a whole can be achieved by using the inverter motor and the inverter.(e) Because the motor (e.g., a variable-speed electric motor) is used as the speed-change motive source, the speed change is performed accurately and smoothly.(f) Because the planetary gears are of a single pinion type, the differential planetary gear assembly has a high-mechanical efficiency and is suitable for a high-speed operation.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a differential planetary gear apparatus, and a starting apparatus and method for a differential planetary gear apparatus.