JP2660670B2 - Hydraulic continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic continuously variable transmission, and more particularly to a continuously variable transmission used when a driven machine is driven by the output of a prime mover whose rotational speed fluctuates.

[0002]

2. Description of the Related Art Conventionally, in order to cope with the trend of reducing operating expenses and increasing power consumption during operation, a surplus of a main engine with high engine efficiency has been used instead of a diesel generator which has been used in the past. 2. Description of the Related Art A marine generator drive device (commonly referred to as "shaft generator") that drives a generator using motive power has been used. Hereinafter, a generator driving device mounted on a ship will be described as an example.

[0003] As the marine generator driving device, there is the following system. That is, (a) the main engine and the generator are connected via a wet-type hydraulic multi-plate clutch, and the rotational speed of the generator is controlled by utilizing the slip characteristic by changing the operating oil pressure of the wet-type hydraulic multi-plate clutch. method. (B) A system in which the main engine and the generator are connected via an eddy current type electromagnetic clutch, and the rotation speed of the generator is controlled by utilizing the slip characteristic by changing the excitation voltage of the eddy current type electromagnetic clutch. (C) Connect a variable displacement hydraulic pump to the main engine, connect a fixed displacement hydraulic motor to the generator, and control the discharge flow rate of the variable displacement hydraulic pump to rotate the fixed displacement hydraulic motor, that is, the generator. A method of controlling speed. (D) The output shaft of the differential gear device is connected to the generator, one of the input shafts is connected to the main engine, the other input shaft is connected to the fixed displacement hydraulic motor, and the variable displacement hydraulic pump is connected to the main engine. By controlling the discharge flow rate of the variable displacement hydraulic pump, the rotational speed of the fixed displacement hydraulic motor is controlled to a rotational speed corresponding to the rotational speed of the main engine, and the rotational speed of the output shaft of the differential gear device is controlled. Method to do. (E) A method in which a voltage of which frequency is generated by an AC generator is changed into DC by a rectifier and then converted into AC by an inverter again. Etc. are adopted.

[0004]

However, the conventional marine generator drive apparatus has the following problems.
That is, when the generator as the driven motor is driven by the output of the main engine as the prime mover, when the rotation speed of the generator fluctuates when the rotation speed of the main engine fluctuates, the frequency of the generated electricity fluctuates. And this problem becomes remarkable especially when a plurality of generators are operated in parallel. Here, in order to suppress the rotation speed fluctuation of the generator, if a position control method of detecting and controlling the rotation speed of the generator is adopted, if the rotation speed fluctuation of the generator is caused by the load fluctuation, It is possible to cope with it, but it is not possible to cope with fluctuations in the rotation speed of the prime mover. Must be employed to detect and control the path.

However, in the conventional marine generator driving apparatus, it is difficult to employ the path control in a method other than the method of performing the AC-DC-AC conversion. However, since the rotational speed fluctuation of the main engine appears in the rotational speed fluctuation of the generator, there is a problem that the frequency fluctuation of the generator occurs. Further, in the conventional AC-DC-AC conversion method, there is an advantage that the rotation speed fluctuation of the main engine does not cause the frequency fluctuation of the generated electricity, but the AC-DC conversion,
There are problems such as a reduction in the effective rate of the generated power due to the repetition of the direct-to-cross conversion, and an electromagnetic interference.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. It is an object of the present invention to suppress the influence of the rotation speed fluctuation of a prime mover on the rotation speed of a driven machine and to reduce the influence of the rotation speed of the driven machine. It is an object of the present invention to provide a hydraulic continuously variable transmission in which the rotation speed is stabilized with high precision.

[0007]

According to a first aspect of the present invention, there is provided a hydraulic stepless transmission as means for achieving the above object, comprising a first hydraulic pump connected to a prime mover, and a follower. A connected hydraulic motor, a second hydraulic pump interposed between the first hydraulic pump and the hydraulic motor for setting a required flow rate of the hydraulic motor, and a detection result of a rotation speed of the driven machine or the hydraulic motor. A variable-speed electric motor that drives the second hydraulic pump based on the pressure and a pressure that is provided on the primary side of the second hydraulic pump and that maintains a constant pressure difference between the primary side and the secondary side of the second hydraulic pump. And a compensating valve.

According to a second aspect of the present invention, in the continuously variable transmission according to the first aspect, the first hydraulic pump comprises a variable displacement hydraulic pump, and the rotational speed of the motor is detected. The discharge flow rate is controlled based on the result. Further, according to a third aspect of the present invention, in the continuously variable transmission according to the first aspect, the first hydraulic pump comprises a variable displacement hydraulic pump, and a suction port of the first hydraulic pump is connected to the first hydraulic pump. A third hydraulic pump is connected to the hydraulic oil outlet of the hydraulic motor and connected to a suction port of the first hydraulic pump, and the third hydraulic pump has a discharge flow rate of the first and second hydraulic pumps. And the discharge flow rate of the third hydraulic pump is set to a constant pressure by the flow rate control mechanism of the first hydraulic pump.

[0009]

According to the first aspect of the present invention, there is provided a hydraulic stepless transmission, wherein a first hydraulic pump connected to a prime mover, a hydraulic motor connected to a driven machine, and a hydraulic motor connected between the first hydraulic pump and the hydraulic motor. A second hydraulic pump interposed in the hydraulic motor for setting a required flow rate of the hydraulic motor; a variable speed electric motor for driving the second hydraulic pump based on a detection result of a rotation speed of the driven machine or the hydraulic motor; A pressure compensating valve provided on the primary side of the second hydraulic pump to maintain a constant pressure difference between the primary side and the secondary side of the second hydraulic pump; The discharge pressure of the pump is reduced by the pressure difference between the primary side and the secondary side set in the second hydraulic pump, the second hydraulic pump pressurizes the underpressure of the pressure difference, and the discharge capacity of the first hydraulic pump is increased. Minimum number of rotations in the rotation speed fluctuation range of the motor At the speed, set to discharge a flow rate more than the required flow rate at the set rotation speed of the hydraulic motor, and set the rotation speed of the variable speed motor to the rotation speed of the hydraulic motor based on the detection result of the rotation speed of the driven machine or the hydraulic motor. By controlling the rotation speed to be equal to the rotation speed, the second hydraulic pump shunts the flow required for rotating the hydraulic motor at the set rotation speed from the discharge flow rate of the first hydraulic pump, thereby changing the rotation speed of the motor and The rotational speed of the driven machine is maintained at the set rotational speed with high accuracy without being affected by the acceleration / deceleration of the motor.

In the hydraulic continuously variable transmission according to a second aspect of the present invention, the first hydraulic pump is formed of a variable displacement hydraulic pump, and the discharge flow rate is controlled based on the detection result of the rotation speed of the prime mover. By controlling the discharge flow rate of the first hydraulic pump to be equal to or more than the required flow rate of the hydraulic motor,
By controlling the rotation speed of the variable speed motor so that the rotation speed of the hydraulic motor becomes the set rotation speed based on the detection result of the rotation speed of the driven machine or the hydraulic motor, the discharge of the first hydraulic pump by the second hydraulic pump is performed. Divide the flow rate required to rotate the hydraulic motor at the set rotation speed from the flow rate, and accurately adjust the rotation speed of the driven machine to the set rotation speed without being affected by the rotation speed fluctuation of the prime mover and the acceleration / deceleration at the time of fluctuation. In addition to acting to maintain the setting, it acts to reduce power loss as compared with the case where a fixed displacement hydraulic pump is used as the first hydraulic pump.

Further, in the hydraulic stepless transmission according to a third aspect of the present invention, the first hydraulic pump comprises a variable displacement hydraulic pump, and a suction port of the first hydraulic pump and a hydraulic oil outlet of the hydraulic motor are provided. And a third hydraulic pump connected to a suction port of the first hydraulic pump is provided, and a discharge flow rate of the third hydraulic pump is equal to or greater than a leak flow rate of the first and second hydraulic pumps and the hydraulic motor. In addition to the setting, the discharge pressure of the third hydraulic pump is controlled to a constant pressure by the flow control mechanism of the first hydraulic pump. Shunts the flow rate required to rotate the motor, and acts to maintain the rotation speed of the driven machine at the set rotation speed with high accuracy without being affected by the rotation speed fluctuation of the prime mover and the acceleration / deceleration at the time of the fluctuation. In addition, power loss is reduced as compared with a case where a fixed displacement hydraulic pump is used as the first hydraulic pump, and shortage of flow due to a response delay during control of the first hydraulic pump which is a variable displacement hydraulic pump is prevented. Works.

As described above, the hydraulic continuously variable transmission according to the present invention uses the discharge flow rate of the first hydraulic pump, which is affected by the rotation speed of the prime mover, to control the driven machine (or the hydraulic motor driving the driven machine). The hydraulic motor is driven based on the detection result of the rotational speed, and the hydraulic motor is driven by shunting the required flow rate of the hydraulic motor that drives the driven machine by the second hydraulic pump without being affected by the rotational speed of the prime mover. It is possible to provide a device capable of stabilizing the rotation speed of the driven machine with high accuracy without being affected by speed fluctuations or the like.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Here, FIGS.
FIG. 1 is a hydraulic circuit diagram of a first embodiment, FIG. 2 is a hydraulic circuit diagram of a second embodiment, and FIG. 3 is a main part hydraulic circuit diagram of a third embodiment.

The hydraulic continuously variable transmission according to the first embodiment is a continuously variable transmission used when a generator is driven by the output of a main engine of a ship. A first hydraulic pump 3 connected to the main engine 1, a hydraulic motor 4 connected to the generator 2, a first hydraulic pump 3 and a hydraulic motor 4
And a second hydraulic pump 5 interposed between the second hydraulic pump 5 and the second hydraulic pump 5 for setting a required flow rate of the hydraulic motor 4, and for driving the second hydraulic pump 5 based on the detection result of the rotation speed of the generator 2 or the hydraulic motor 4. A main motor having a variable speed motor 6 and a pressure compensating valve 7 provided on the primary side of the second hydraulic pump 5 for maintaining a constant pressure difference between the primary side and the secondary side of the second hydraulic pump 5 From the discharge flow rate of the first hydraulic pump 3 driven by
(Or the hydraulic motor 4 for driving the generator 2) is configured to drive the hydraulic motor 4 by shunting the required flow rate of the hydraulic motor 4 by the second hydraulic pump 5 driven based on the detection result of the rotation speed of the hydraulic motor 4. doing.

The first hydraulic pump 3 is composed of a variable displacement hydraulic pump having a built-in flow control mechanism 3a for controlling a discharge flow rate by pilot pressure, and is connected to the main engine 1 via a shaft coupling 11. The hydraulic motor 4 is composed of a fixed displacement hydraulic motor, and is connected to the generator 2 via a shaft coupling 12. The second hydraulic pump 5 is composed of a fixed displacement hydraulic pump, and is connected to the variable speed motor 6 via a shaft coupling 13.

The discharge port of the first hydraulic pump 3 and the second
The suction port of the hydraulic pump 5 is connected by a pipe 14, and the discharge port of the second hydraulic pump 5 is connected by a pipe 15 to the hydraulic oil inlet of the hydraulic motor 4. The suction port (primary side) of the second hydraulic pump 5 branches from the pipe 14 and
A pressure compensating valve 7 for maintaining the pressure difference between the primary side and the secondary side constant, and connecting the suction port of the first hydraulic pump 3 and the hydraulic oil outlet of the hydraulic motor 4 with a pipe 16; 16
Is connected to a third hydraulic pump 18 via a check valve 17, and a pilot pipe 19 branched from the pipe 16 is connected to a flow control mechanism 3a of the first hydraulic pump 3 to form a closed circuit.

The third hydraulic pump 18 is a fixed displacement hydraulic pump, and is connected to a motor 20 via a shaft coupling 21. The capacity of the third hydraulic pump 18 is set so as to discharge hydraulic oil equal to or larger than the leak flow rate of the first hydraulic pump 3, the hydraulic motor 4, and the second hydraulic pump 5.

Here, the flow control mechanism 3a of the first hydraulic pump 3 adjusts the flow rate of hydraulic oil flowing out of the pipe 16 by the hydraulic motor 4 (the theoretical flow rate required for operating the hydraulic motor 4 at a set rotation speed). Then, the flow rate discharged by the third hydraulic pump 18 is added, and the discharge flow rate is controlled such that the pressure in the pipe 16 maintains the set pressure with respect to the added flow rate. That is, the flow control mechanism 3a decreases the discharge flow rate when the pressure in the pipe 16 is equal to or lower than the set pressure (decreases the discharge flow rate per rotation), and increases the discharge flow rate when the pressure in the pipe 16 exceeds the set pressure. (The discharge flow rate per rotation is increased), and the pressure in the pipe 16 is maintained at the set pressure.

The flow control mechanism 3a of the first hydraulic pump 3
In order to cope with a response delay in the operation of the first hydraulic pump 3, in order to increase the discharge flow rate of the first hydraulic pump 3,
The hydraulic oil in the circuit is replaced by increasing the flow rate discharged by the hydraulic pump 18 so that the second hydraulic pump 5 does not cause the shortage of the divided flow rate and causing the remaining divided flow rate to flow out of the circuit. This prevents the oil temperature in the circuit from rising.

A sequence valve 23 is interposed in a pipe 14 between the first hydraulic pump 3 and the second hydraulic pump 5, and a sequence valve 24 is interposed in a pipe 15 between the second hydraulic pump 15 and the hydraulic motor 4. The sequence valve 23 of the pipe 14 and the second
An electromagnetically operated relief valve 26 is connected between the hydraulic pump 5, a sequence valve 24 of the pipe 15 and an electromagnetically operated relief valve 27 are connected to the hydraulic motor 4, and the discharge port of the third pump 18 is connected to the check valve 17. A relief valve 28 is connected between them,
A check valve 29 is connected to the suction port of the first hydraulic pump 3.

Further, check valves 31 to 33 are provided for braking when the hydraulic motor 4 is stopped. This is because when the generator 2 is stopped, it cannot be suddenly stopped due to the inertia characteristics of the generator 2. Therefore, a circulation circuit of the operating oil is provided by the check valves 31, 32, and 33, and the braking pressure is gradually applied to the hydraulic motor 4. It is like that. A pressure gauge 35 is connected to the discharge ports of the first hydraulic pump 3, the third hydraulic pump 18, and the second hydraulic pump 5 via a gauge valve 34.

The outflow side of the oil tank 41 is provided with a stop valve 42, a suction filter 43, and a stop valve 44.
Are connected to the suction port of the third hydraulic pump 18 via the check valve 29, the suction port of the first hydraulic pump 3 via the check valve 29, and the hydraulic oil inlet of the hydraulic motor 4 via the check valve 31, respectively. Side (return side) is stop valve 4
5, a first hydraulic pump 3, a hydraulic motor 4, a second hydraulic pump 6, a pressure compensating valve via a circuit in which a check valve 49 is connected in parallel to a series circuit of a hydraulic oil cooler 46, a line filter 47, and a stop valve 48. 7. Electromagnetic operated relief valve 2
6, 27 and a relief valve 28 respectively.

In the present embodiment, a pressure difference of 1 MPa is set between the primary side and the secondary side of the second hydraulic pump by the pressure compensating valve 7 attached to the second hydraulic pump 5, and the sequence valve 24 Was set to 1.5 MPa. The pressure in the pipe 16 was set to 1 MPa. Further, the flow rate discharged by the third pump 18 is 2 to 2 of the leak flow rate from the circuit.
The flow rate was set to 2.5 times (corresponding to approximately 25% of the flow rate circulating in the circuit).

The operation of the hydraulic continuously variable transmission according to this embodiment will be described. First, the first hydraulic pump 3 and the third hydraulic pump 18 with the electromagnetically operated relief valve 26 demagnetized.
Is started, the discharge pressure is controlled by the sequence valve 23 to the pressure required to operate the discharge flow rate control mechanism of the first hydraulic pump 3, and the discharge flow rate is controlled to the flow rate at which the pipe 16 becomes the set pressure. At this time, since the pressure compensating valve 7 is in the “open” state due to its structure, all the flow rate discharged from the first hydraulic pump 3 is discharged out of the circuit by the electromagnetically operated relief valve 26 and the pressure compensating valve 7.

Next, when the electromagnetically operated relief valve 27 is excited and the variable speed motor 6 is gradually accelerated, the second hydraulic pump 5 starts shunting from the discharge flow rate of the first hydraulic pump 3, so that the hydraulic motor 4 starts operation. At this time, the discharge pressure of the second hydraulic pump 5 becomes the set pressure of the sequence valve 24 because the hydraulic motor 4 is operated without load, and the set pressure of the pressure compensating valve 7 is set to be equal to or less than the set pressure of the sequence valve 24. Therefore, by exciting the electromagnetically operated relief valve 26, a part of the flow rate discharged from the first hydraulic pump 3 is discharged out of the circuit by the pressure compensating valve 7, and the pressure on the primary side of the second hydraulic pump 3 is reduced by the sequence valve. The pressure becomes lower than the pressure set by the pressure compensation valve 7.

The pressure compensating valve 7 prevents the second hydraulic pump 5 from being directly driven by the first hydraulic pump 3 when setting the rotation speed of the variable speed motor 6, that is, the second hydraulic pump 5 does not operate as a hydraulic motor. So the second
The primary side of the hydraulic pump 5 acts so as to have a lower pressure than the secondary side. This pressure difference is controlled to be substantially constant regardless of the load on the generator 2. Then, the second hydraulic pump 5 is discharged by the first hydraulic pump 3 at a pressure lower than the pressure difference between the primary side and the secondary side which is set with respect to the second hydraulic pump 5.
The required pressure of the hydraulic motor 4 is obtained by increasing the pressure difference between the primary side and the secondary side, which is an insufficient pressure.

Therefore, the variable speed motor 6 is accelerated to increase the rotation speed of the hydraulic motor 4, and when the rotation speed of the hydraulic motor 4 reaches the set rotation speed, the acceleration of the variable speed motor 6 is stopped to perform automatic operation. Switch. In this case, the operation is switched to the operation of the apparatus of the present embodiment after confirming the rotation speed or the frequency of another generator that has been operating in advance.

After switching to automatic operation, the hydraulic motor 4
Alternatively, the rotational speed of the generator 2 is detected, the detected value is compared with a preset set value, and a speed increase / decrease command is output to the variable speed motor 6 according to the comparison result. The speed is controlled so that the second hydraulic pump 5 performs the branch flow so that the rotation speeds of the hydraulic motor 4 and the generator 2 become the set rotation speed.

As described above, in the hydraulic continuously variable transmission according to the present embodiment, the discharge flow rate of the first hydraulic pump 3 which is a variable displacement hydraulic pump is adjusted to the required flow rate of the hydraulic motor 4 which is a fixed displacement hydraulic motor. Set to have room for
From the discharge flow rate of the first hydraulic pump 3, the variable speed motor 6
The required flow rate is divided by the second hydraulic pump 5 driven by the motor, so that even if the rotational speed of the main engine 1 fluctuates, the rotational speed (frequency) fluctuation of the generator 2 is suppressed and the set rotational speed can be accurately adjusted. It works so that the setting can be maintained.

The discharge flow control mechanism 3a of the first hydraulic pump 3 connected to the main engine 1 operates with a slight delay with respect to fluctuations in the rotational speed of the main engine 1.
Is set so as to have a margin with respect to the predetermined flow rate of the hydraulic motor 4, the discharge flow rate does not become insufficient.

Further, the first variable displacement hydraulic pump,
When diverting from the flow rate discharged from the hydraulic pump 3, the second hydraulic pump 5 which is a fixed displacement hydraulic pump is used as a flow control valve, and the first hydraulic pump 3 discharges to the second hydraulic pump 5. Since the flow rate is larger than the required flow rate, the first hydraulic pump 3 acts as a boost pump, so that the flow dividing effect of the second hydraulic pump 5 is improved.

Further, even when the load fluctuation on the generator 2 or the hydraulic motor 4 is large, the rotation speed fluctuation range of the generator 2 is small because the change in the volumetric efficiency of the hydraulic motor 4 and the second hydraulic pump 5 is small. In addition, the frequency fluctuation is very small as compared with the method using no other hydraulic equipment. Although the operation of the pressure compensating valve 7 is slightly delayed due to the load fluctuation, the second hydraulic pump 5 which is a fixed displacement pump is provided for the flow rate control, and the rotation speed of the second hydraulic pump 5 is controlled by the variable speed motor 6. Since the control is performed, the influence on the frequency fluctuation is small. Even when the load fluctuation on the generator 2 or the hydraulic motor 4 is large, the load fluctuation and the rotation speed fluctuation of the second hydraulic pump 5, which is a fixed displacement hydraulic pump, are small by the action of the pressure compensating valve 7. 6 is stable, and the control accuracy of the rotational speed is improved.

In this case, by maintaining the rotation speed of the second hydraulic pump 5 at the rotation speed of the generator 2 or at a rotation speed proportional thereto, the rotation speed of the generator 2 can be maintained at the set rotation speed. However, in practice, the pressure changes depending on the load of the generator 2, and it is necessary to slightly adjust the rotation speed in order to compensate for the leak amount of the first hydraulic pump 53 and the like.

If the rotation speed of the main engine 1 fluctuates within an allowable range, the required flow rate can be divided regardless of the rotation speed fluctuation and the acceleration / deceleration of the rotation speed fluctuation, and the second hydraulic pressure for controlling the flow rate can be divided. By using a fixed displacement hydraulic pump as the pump 5, the flow rate can be controlled by the product of the rotational speed and the displacement volume of the hydraulic pump 5, so that a flow control valve is used or the flow control of the variable displacement hydraulic pump is performed. Dividing can be performed more easily and with higher precision than when a mechanism is used.

The rotation speed of the variable speed motor 6 is controlled by the generator 2
Alternatively, the rotation speed of the hydraulic motor 4 is detected, that is, the position control is adopted. However, in order to control the required flow rate of the hydraulic motor 4 regardless of the rotation speed fluctuation of the main engine 1,
Although the position control is performed instead of the path control, control accuracy substantially similar to the case of employing the path control can be obtained. This means that the control system does not follow the rotation speed fluctuation of the main engine 1 but the generator 2 controls the generator 2 to control the generator using the generator as a control base. It shows that it is stable.

Next, in the hydraulic stepless disguise apparatus of the second embodiment, the first hydraulic pump 3 composed of a variable displacement hydraulic pump of the first embodiment is replaced with a first hydraulic pump composed of a fixed displacement hydraulic pump. The hydraulic pump 53 is used, and the hydraulic circuit employed in the first embodiment is a closed circuit (closed circuit), whereas the second embodiment is an open circuit (open circuit).

Here, the discharge flow rate of the first hydraulic pump 53 is set so as to be equal to or higher than the flow rate required for the hydraulic motor 4 to maintain the set rotational speed at the minimum rotational speed of the first hydraulic pump 53, and Hydraulic motor 4 for discharge pressure
Is set to a pressure slightly lower than the required pressure, the required flow to the hydraulic motor 4 is controlled by controlling the rotation speed of the second hydraulic pump 5 to the required rotation speed from the discharge flow of the first hydraulic pump 53. It becomes possible to do. Because the first hydraulic pump 53 is a fixed displacement hydraulic pump, the discharge flow rate is
However, there is a drawback that the operating loss becomes large at a high rotation speed because the flow rate is increased compared to the required flow rate.

Next, the hydraulic stepless disguise apparatus of the third embodiment uses the first hydraulic pump 3 composed of a variable displacement hydraulic pump as in the first embodiment. By detecting the rotation speed of the main engine 1 and inputting a signal proportional to the fluctuation of the rotation speed to the first hydraulic pump 3 as an electric signal or a fluid signal, the discharge flow rate of the first hydraulic pump 3 The flow is controlled so as to be equal to or more than the flow rate, and the power loss is small as in the first embodiment as compared with the case where the fixed displacement hydraulic pump is used.
Fuel savings can be achieved.

It should be noted that the present invention is not limited to the above-described embodiment, but includes a configuration which can be modified and implemented without changing the gist of the present invention. By the way, in the above embodiment, an example in which the present invention is applied to a drive device of a marine generator has been described. However, for example, the present invention may be applied to a drive device of a generator of a vehicle, an air conditioner, or a drive device of a refrigeration / refrigeration device. Can be.

[0040]

As is apparent from the above description, according to the hydraulic continuously variable transmission of the first aspect of the present invention, the first hydraulic pump connected to the prime mover and the hydraulic motor connected to the driven machine A second hydraulic pump interposed between the first hydraulic pump and the hydraulic motor to set a required flow rate of the hydraulic motor; and a second hydraulic pump based on a detection result of a rotation speed of the driven machine or the hydraulic motor. A variable speed motor for driving the second hydraulic pump; and a pressure compensating valve provided on the primary side of the second hydraulic pump for maintaining a constant pressure difference between the primary side and the secondary side of the second hydraulic pump. Therefore, the first hydraulic pump
Divides the flow rate required to rotate the hydraulic motor at the set rotation speed from the discharge flow rate of the hydraulic pump, and sets the rotation speed of the driven machine without being affected by the rotation speed fluctuation of the prime mover and the acceleration / deceleration during the fluctuation. This has the effect that the setting can be maintained with high accuracy.

According to the second aspect of the present invention, the first hydraulic pump is a variable displacement hydraulic pump, and the discharge flow rate is controlled based on the result of detection of the rotation speed of the prime mover. Therefore, the flow rate required for rotating the hydraulic motor at the set rotation speed from the discharge flow rate of the first hydraulic pump by the second hydraulic pump is diverted to be affected by the rotational speed fluctuation of the prime mover and the acceleration / deceleration at the time of the fluctuation. Therefore, the rotation speed of the driven machine can be set and maintained at the set rotation speed with high accuracy, and the power loss can be reduced as compared with the case where a fixed displacement hydraulic pump is used as the first hydraulic pump.

Further, according to the third aspect of the present invention, the first hydraulic pump is a variable displacement hydraulic pump, and the suction port of the first hydraulic pump and the hydraulic oil flow of the hydraulic motor are provided. An outlet is connected and a third hydraulic pump is provided connected to a suction port of the first hydraulic pump, and a discharge flow rate of the third hydraulic pump is set to a leak flow rate of the first and second hydraulic pumps and the hydraulic motor. In addition to the above settings, the discharge pressure of the third hydraulic pump is controlled to a constant pressure by the flow control mechanism of the first hydraulic pump, so that the second hydraulic pump rotates the hydraulic motor from the discharge flow rate of the first hydraulic pump. If the flow required for rotating at the speed can be divided and the rotational speed of the driven machine can be set and maintained at the set rotational speed with high accuracy without being affected by the rotational speed fluctuation of the prime mover and the acceleration / deceleration at the time of the fluctuation. Both In addition, the power loss is reduced as compared with the case where a fixed displacement hydraulic pump is used as the first hydraulic pump, and shortage of flow due to a response delay at the time of controlling the first hydraulic pump which is a variable displacement hydraulic pump can be prevented. Have. Further, in the case of the present invention, it is not necessary to control the discharge flow rate of the first hydraulic pump by detecting the rotation speed of the prime mover, so that the control is easily performed.

As described above, according to the hydraulic continuously variable transmission of the present invention, the driven motor (or the hydraulic motor that drives the driven motor) is determined based on the discharge flow rate of the first hydraulic pump that is affected by the rotation speed of the prime mover. ), The hydraulic motor is driven by shunting the required flow rate of the hydraulic motor that drives the driven machine by the second hydraulic pump that is driven based on the rotational speed detection result and is not affected by the rotating speed of the prime mover. Therefore, it is possible to provide a device that can stabilize the rotation speed of the driven machine with high accuracy without being affected by the rotation speed fluctuation or the like.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a main part hydraulic circuit diagram showing a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main engine (motor), 2 ... Generator (follower), 3, 53 ... 1st hydraulic pump, 3a ... Flow control mechanism, 4 ... Hydraulic motor, 5 ... -2nd hydraulic pump, 6 ... variable speed electric motor, 7 ... pressure compensation valve, 18
... third hydraulic pump, 41 ... oil tank

Claims (3)

(57) [Claims] 1. A hydraulic continuously variable transmission used for driving a driven machine with an output of a prime mover whose rotational speed fluctuates, wherein the continuously variable transmission comprises a first hydraulic pump connected to the prime mover, A hydraulic motor connected to the driven machine, a second hydraulic pump interposed between the first hydraulic pump and the hydraulic motor for setting a required flow rate of the hydraulic motor, and rotation of the driven machine or the hydraulic motor; A variable speed electric motor that drives the second hydraulic pump based on the speed detection result; and a constant pressure difference between the primary and secondary sides of the second hydraulic pump that is provided on the primary side of the second hydraulic pump. And a pressure compensating valve for maintaining the hydraulic pressure. 2. The hydraulic continuously variable transmission according to claim 1, wherein the first hydraulic pump comprises a variable displacement hydraulic pump, and a discharge flow rate is controlled based on a detection result of a rotation speed of the prime mover. 3. The first hydraulic pump comprises a variable displacement hydraulic pump, and a suction port of the first hydraulic pump is connected to a hydraulic oil outlet of a hydraulic motor, and the first hydraulic pump is connected to a suction port of the first hydraulic pump. A connected third hydraulic pump is provided,
The discharge flow rate of the third hydraulic pump is set to be equal to or more than the leak flow rate of the first and second hydraulic pumps and the hydraulic motor, and the discharge pressure of the third hydraulic pump is made constant by the flow control mechanism of the first hydraulic pump. The hydraulic continuously variable transmission according to claim 1.