WO2006025518A1

WO2006025518A1 - Hydraulic drive device and speed change method in hydraulic drive device

Info

Publication number: WO2006025518A1
Application number: PCT/JP2005/016090
Authority: WO
Inventors: Naoki Ishizaki; Hikosaburou Hiraki
Original assignee: Komatsu Ltd.
Priority date: 2004-09-02
Filing date: 2005-09-02
Publication date: 2006-03-09
Also published as: WO2006025519A1; JP2007315405A

Abstract

A hydraulic pump connected to a drive source and a hydraulic motor are connected to a closed circuit via oil paths. A hydraulic pump-motor connected to each oil path is connected to the hydraulic pump through a first clutch. The hydraulic pump-motor and the hydraulic motor are connected through a second clutch. At the time of starting the drive source, the capacity of the hydraulic pump is set to zero, the capacity of the hydraulic pump-motor to the maximum, the first clutch to OFF, and the second clutch to ON. The capacity of the hydraulic pump is increased to the maximum to increase the rotation speed of an output shaft connected to the hydraulic motor. After the capacity of the hydraulic pump is at the maximum, the hydraulic pump-motor is caused to perform motor function to reduce the capacity from the maximum to zero and the rotation speed of the output shaft is further increased. After the capacity of the hydraulic pump-motor reaches zero, the first clutch is set to ON and the second clutch is set to OFF. This causes the hydraulic pump-motor to perform pump function to increase the capacity from zero to the maximum, further increasing the rotation speed of the output shaft. A hydraulic drive device that has high efficiency in high speed traveling, that has excellent acceleration characteristics both in low and high speeds, and in which the output shaft can be rotated at a high speed is provided.

Description

Hydraulic drive device and speed change method in hydraulic drive device

Technical field

The present invention relates to a hydraulic drive device in which a closed circuit is configured by a hydraulic pump and a hydraulic motor, and a speed change method in the hydraulic drive device.

Background art

Conventionally, as a hydraulic drive device used in, for example, a vehicle, a hydraulic drive device in which a hydraulic pump driven by an engine and a hydraulic motor are combined is widely used. As a hydraulic drive device using a hydraulic pump and two hydraulic motors, a hydraulic drive device shown in FIG. 12 (see, for example, Patent Document 1) has been conventionally known.

Conventionally, a hydraulic drive apparatus using one hydraulic pump and one hydraulic motor has a configuration as shown in FIG. A hydraulic drive device le shown in FIG. 10 will be described as Conventional Example 1 in the present invention. In FIG. 10, the rotational output of the engine power that is the drive source 42 is transmitted to the variable displacement hydraulic pump 44 via the drive shaft 43. When the variable displacement hydraulic pump 44 is rotationally driven, the variable displacement hydraulic motor 45 including the output shaft 46 is rotationally driven by the discharge hydraulic oil from the variable displacement hydraulic pump 44.

[0004] The variable displacement hydraulic pump 44 and the variable displacement hydraulic motor 45 are configured in a closed circuit via oil passages 47 and 48. When the drive source 42 is started to increase the discharge capacity of the variable displacement hydraulic pump 44, the rotational speed of the variable displacement hydraulic motor 45 increases. Therefore, the vehicle traveling by the rotational force from the output shaft of the variable capacity hydraulic motor 45 is accelerated.

[0005] When the capacity of the state force variable displacement hydraulic motor 45 is decreased, the vehicle can be further accelerated. By tilting the swash plate of the variable displacement hydraulic pump 44 in one side direction, the vehicle can be driven forward, and the swash plate of the variable displacement hydraulic pump 44 is moved to the other side opposite to the one side direction. By tilting in the direction, the vehicle can be driven backwards

Next, a speed change method and operation of the hydraulic drive device le will be described with reference to FIG. In FIG. 11, all the horizontal axes are speed command values that are commands for adjusting the displacement of the variable displacement hydraulic pump 44 and the variable displacement hydraulic motor 45. The vertical axis of the graph (g) indicates the capacity of the variable displacement hydraulic motor 45, and the vertical axis of the graph (h) indicates the capacity of the variable displacement hydraulic pump 44. The vertical axis of graph (j) indicates the rotational speed of output shaft 46, and the vertical axis of graph (k) indicates the volumetric efficiency 7? In variable displacement hydraulic pump 44 and variable displacement hydraulic motor 45, that is, The power transmission efficiency in the hydraulic drive device is shown.

[0007] Referring to the graphs (g) and (h) in FIG.

1) When starting the drive source 42, the capacity of the variable displacement hydraulic motor 45 is set to the maximum capacity V45max, and the capacity of the variable displacement hydraulic pump 44 is adjusted to zero capacity.

2) When accelerating the vehicle, the capacity of the variable displacement hydraulic pump 44 is adjusted so that the maximum capacity V44max is obtained by increasing the capacity of the zero capacity. That is, the capacity of the variable displacement hydraulic pump 44 is increased together with the speed command value so that the speed command value A reaches the maximum capacity V44ma _X.

[0009] 3) Next, by increasing the speed command value above the speed command value A, the capacity of the variable displacement hydraulic motor 45 is adjusted so as to reduce the maximum capacity V45max force. That is, the capacity of the variable displacement hydraulic motor 45 is decreased from the maximum capacity V45max as the speed command value increases, and the speed command value B is set to a predetermined minimum capacity V45min.

As a result, as shown in the graph (j), the rotation speed of the output shaft 46 is increased from the state where the rotation speed is zero at the speed command value A to the rotation speed N2, and at the speed command value B, Becomes the maximum speed N3. Further, as shown in the graph (k), the volumetric efficiency r? Increases as the capacity increases in the variable displacement hydraulic pump 44. The volumetric efficiency can be maximized at the maximum capacity V44max. Therefore, the volumetric efficiency becomes r? 2 at the speed command value A. On the other hand, since the volumetric efficiency of the variable displacement hydraulic motor 45 decreases as the capacity is reduced, the volumetric efficiency is 7 to 1 at the speed command value B.

A hydraulic drive device If shown in FIG. 12 will be described as Conventional Example 2 in the present invention. In FIG. 12, a variable displacement hydraulic pump 54 that is rotationally driven by a drive source such as an engine (not shown) is connected to a fixed displacement hydraulic motor 55 and a variable displacement hydraulic motor 60 via oil passages 57 and 58, respectively. A closed circuit is formed between them. [0012] The motor shaft 55a of the fixed displacement hydraulic motor 55 is connected to the output shaft 56 via a gear device 62. The motor shaft 60 a of the variable displacement hydraulic motor 60 is connected to the output shaft 56 via a gear device 63 and a clutch 64.

Next, a speed change method and operation of the hydraulic drive device If will be described with reference to FIG. In FIG. 13, the horizontal axis is all speed command values. The vertical axis of the graph (m) indicates the capacity of the fixed displacement hydraulic motor 55, the vertical axis of the graph (n) indicates the capacity of the variable displacement hydraulic pump 54, and the vertical axis of the graph (p) indicates the variable displacement hydraulic pressure. The capacity of the motor 60 is shown. Further, the vertical axis of the graph (q) indicates the rotational speed of the output shaft 56, and the vertical axis of the graph (r) indicates the volumetric efficiency in the hydraulic drive device le.

[0014] Referring to the graphs (m), (n), and (p) in FIG.

1) At the start of a drive source (not shown), the capacity of the fixed displacement hydraulic motor 55 is the capacity V55. The capacity of the variable displacement hydraulic pump 54 is set to zero, and the capacity of the variable displacement hydraulic motor 60 is adjusted to the maximum capacity V60max. Further, the clutch 64 is kept in the engaged state.

[0015] 2) When accelerating the vehicle, the displacement of the variable displacement hydraulic pump 54 is adjusted so that the maximum displacement V54max is obtained by increasing the zero displacement force. That is, the capacity of the variable displacement hydraulic pump 54 is increased together with the speed command value so that the speed command value A reaches the maximum capacity V54max.

[0016] 3) Next, by increasing the speed command value over the speed command value A, the capacity of the variable displacement hydraulic motor 60 is adjusted so that the maximum capacity V60max force is also reduced to zero capacity. That is, the capacity of the variable displacement hydraulic motor 60 is reduced to the maximum capacity V 60max force as the speed command value increases, and the speed command value B is set to zero capacity. After the capacity of the variable displacement hydraulic motor 60 reaches zero, the clutch 64 is released and the rotational drive for the output shaft 56 is switched to the drive by the fixed displacement hydraulic motor 55 alone.

As a result, as shown in the graph (q), the rotation speed of the output shaft 56 is increased from the zero rotation speed state to the rotation speed N1 at the speed command value A, and the maximum speed is reached at the speed command value B. The number of turns becomes N2. As shown in the graph (r), the volumetric efficiency increases from 7 to 2 between the speed command value zero and the speed command value A. Volume efficiency drops to 7 ~ 0 until B. However, at the speed command value B, the variable displacement hydraulic motor 60 is disconnected from the output shaft 56 by releasing the clutch 64, and the output shaft 56 is switched to drive only by the fixed displacement hydraulic motor 55. As a result, the volumetric efficiency can be increased to 7-2.

Patent Document 1: Japanese Patent Laid-Open No. 2-240442

Disclosure of the invention

Problems to be solved by the invention

[0018] In the hydraulic drive devices described in the conventional examples 1 and 2, a continuously variable transmission can be performed to increase the vehicle speed to a predetermined speed. However, the hydraulic drive apparatus shown in the conventional example 1 has a problem that the volumetric efficiency is lowered when the rotational speed of the output shaft 46 is increased, that is, when the vehicle is traveling at high speed. In general, as the capacity force S decreases, the volumetric efficiency decreases drastically. Therefore, the gear ratio obtained by continuously variable transmission is about three times the gear ratio, and the force cannot be obtained.

[0019] In the hydraulic drive device as shown in Conventional Example 2, since one hydraulic pump and two hydraulic motors are used, the gear ratio obtained by continuously variable transmission can be improved somewhat. Only 5-6 times the gear ratio was obtained.

[0020] Further, in order to obtain a large gear ratio, a mechanical transmission device was further provided, and it was necessary to perform two-stage gear shifting by a hydraulic drive device and a mechanical device. However, in order to further arrange the mechanical mission device, a space for mounting the mechanical mission device is required. It has been difficult to secure a space for mounting a mechanical mission device on a traveling vehicle.

[0021] Further, in the mechanical transmission device, the output torque must be cut off by the clutch without fail when the gear ratio is switched. For this reason, at the time of shifting in the mechanical transmission device, a so-called torque out phenomenon occurs in which the output torque is not transmitted to the tire. For example, if the gear ratio of the mechanical transmission device is switched while climbing up, the vehicle may temporarily decelerate. In addition, a shift shock occurs in the mechanical transmission device, which adversely affects riding comfort.

[0022] The present invention has been made paying attention to the above-described problems, and is used in a hydraulic drive device. It is an object of the present invention to provide a hydraulic drive device and a speed change method in the hydraulic drive device that can increase the gear ratio of the continuously variable transmission and increase the volumetric efficiency when the vehicle is traveling at high speed.

Means for solving the problem

[0023] In order to achieve the above object, in the first aspect of the invention, in the hydraulic drive device, the hydraulic pump driven by the drive source is connected to the hydraulic pump in a closed circuit, and is connected to the output shaft. Hydraulic motor, variable displacement hydraulic pump connected in parallel with the hydraulic pump and the hydraulic motor in a closed circuit 'motor, pump shaft of the hydraulic pump and the variable displacement hydraulic pump · motor pump · The main feature is that a first clutch that connects and disconnects the motor shaft and a second clutch that connects and disconnects the pump motor shaft and the motor shaft of the hydraulic motor are provided.

[0024] In the second invention, in the hydraulic drive device having the same configuration as that of the first invention, the most main feature is that a transmission gear is further provided at the connecting portion between the pump shaft and the pump / motor shaft.

In the third aspect of the invention, in the hydraulic drive apparatus having the same configuration as that of the first aspect, the main feature is that a transmission gear is further provided at the connecting portion between the pump motor shaft and the motor shaft.

[0025] In the fourth invention, in the hydraulic drive device, a hydraulic pump driven by the drive source, a hydraulic motor connected to the hydraulic pump in a closed circuit and connected to an output shaft, and the closed circuit A single tilting / variable displacement hydraulic pump / motor connected in a closed circuit in parallel with the hydraulic pump and the hydraulic motor via the connected first oil passage and second oil passage, (1) A switching valve for switching the flow direction of pressure oil in the oil passage and the second oil passage, and the pump shaft of the hydraulic pump and the one-side tilt, variable displacement hydraulic pump, motor pump, and motor shaft are connected and disconnected. The most important feature is that a first clutch and a second clutch that connects and disconnects the pump motor shaft and the motor shaft of the hydraulic motor are provided.

[0026] In the fifth invention, in the speed change method in the hydraulic drive apparatus having the same configuration as in the first invention, when the displacement of the variable displacement hydraulic pump motor is zero, the first clutch is released, and the second The main feature is that the clutch is connected. The invention's effect

[0027] According to the first and fifth inventions, the variable displacement hydraulic pump motor can be used as a pump after being used as a motor. For this reason, it is possible to reduce the space as compared with the case where the hydraulic motor and the hydraulic pump are individually provided, and the number of the hydraulic motors or hydraulic pumps can be reduced.

[0028] According to the second invention, the gear ratio of the transmission gear can be selected as appropriate, and the hydraulic pump and the variable displacement hydraulic pump 'motor can be used at their respective optimum rotational speeds. Therefore, the efficiency can be improved over the entire vehicle speed of the vehicle.

[0029] In the third invention as well, the gear ratio of the transmission gear can be selected as appropriate, so that the hydraulic motor and the variable displacement hydraulic pump motor are used at their optimum rotational speeds. It becomes possible. Therefore, the efficiency can be improved over the entire vehicle speed.

[0030] According to the fourth aspect of the invention, instead of configuring the variable displacement hydraulic pump / motor as a double-tilt type, it is possible to use a single-tilt type that is inexpensive and has a simple structure.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram of a hydraulic drive device. (Example 1)

FIG. 2 is a graph for explaining a speed change method of the hydraulic drive device. (Example 1) [FIG. 3] FIG. 3 is a flowchart for explaining a speed change method of the hydraulic drive device. (Example 1)

FIG. 4 is a schematic configuration diagram of a hydraulic drive device using a variable displacement hydraulic motor. (Example 1)

FIG. 5 is another schematic configuration diagram of the hydraulic drive device. (Example 1)

FIG. 6 is another schematic configuration diagram of the hydraulic drive device. (Example 1)

FIG. 7 is a schematic configuration diagram of a hydraulic drive device. (Example 2)

FIG. 8 is a schematic configuration diagram of a hydraulic drive device. (Example 3)

FIG. 9 is a schematic configuration diagram of a hydraulic drive device. (Example 4)

FIG. 10 is a schematic configuration diagram of a hydraulic drive device. (Conventional example 1)

FIG. 11 is a graph for explaining a speed change method of the hydraulic drive device. (Conventional example 1 )

FIG. 12 is a schematic configuration diagram of a hydraulic drive device. (Conventional example 2)

FIG. 13 is a graph for explaining a speed change method of the hydraulic drive device. (Conventional example 2

)

Explanation of symbols

[0032] 1, la, lb ゝ lc, ld, le, If-… Hydraulic drive

4 ... Hydraulic pump

5 ... Hydraulic motor

6 Output shaft

10, 20, 30, 40 ... Variable displacement hydraulic pump motor

22, 23 ... Transmission gearing

25 ... Switch valve

44 ···· Variable displacement hydraulic pump

45 ... Variable displacement hydraulic motor

46 ··· Output shaft

54 ... Variable displacement hydraulic pump

55 .. Fixed dose hydraulic motor

56 ... Output shaft

60 ... Variable displacement hydraulic motor

62, 63 ... Gearing.

BEST MODE FOR CARRYING OUT THE INVENTION

[0033] Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The configuration of the hydraulic drive device and the speed change method in the hydraulic drive device of the present invention will be described below by taking the hydraulic drive device and the speed change method in the HST device as examples. However, as to the hydraulic drive device and the speed change method thereof according to the present invention, in addition to the shapes and arrangements described below, the shapes and arrangements of the shapes and arrangements that can solve the problems of the present invention can be solved. The configuration can be adopted.

Therefore, the present invention is not limited to the embodiments described below. HST device The present invention can also be suitably applied to other hydraulic drive devices and speed change methods thereof. Embodiments of a hydraulic drive device and a speed change method thereof according to the present invention will be described below with reference to the drawings.

Example 1

FIG. 1 is a schematic configuration diagram of a hydraulic drive device 1 according to the first embodiment. In FIG. 1, a drive source (for example, an engine) 2 and a swash plate-type double displacement type variable displacement hydraulic pump as a hydraulic pump 4 are connected by a drive shaft 3. The fixed displacement hydraulic motor as the hydraulic motor 5 includes an output shaft 6 and can transmit the rotation of the hydraulic motor 5 to the wheels of a running vehicle (not shown).

The hydraulic pump 4 and the hydraulic motor 5 are configured in a closed circuit via oil passages 7 and 8. The swash plate type bi-directional variable displacement hydraulic pump “motor” as the hydraulic pump “motor 10” is connected between the oil passages 7 and 8 via the first oil passage 11 and the second oil passage 12. The first shaft 10 a which is the pump motor shaft of the hydraulic pump motor 10 is connected to the pump shaft 4 a of the hydraulic pump 4 via the first clutch 14. Further, the second shaft 10 b which is the motor shaft of the hydraulic pump “motor 10” is connected to the motor shaft 5 a of the hydraulic motor 5 via the second clutch 16.

In the present invention, in the description of the claims and the description, the shaft that transmits the driving force from the driving source is referred to as a driving shaft, and is connected to the hydraulic pump to form a hydraulic pump motor. The shaft that transmits rotation is called the pump shaft. The shaft that can be connected to the pump shaft by connecting to the hydraulic pump motor is the first shaft, and the shaft that transmits rotation to the output shaft via the hydraulic motor by connecting to the hydraulic pump motor or directly. This is called the second axis. Furthermore, the shaft that can be connected to the second shaft by connecting to the hydraulic motor is called the motor shaft or output shaft. Furthermore, the shaft that is connected to the motor shaft and transmits the rotation to the outside is called the output shaft.

[0038] For this reason, the drive shaft and the pump shaft may be configured by the same shaft. Further, the first shaft and the second shaft or the motor shaft and the output shaft may be constituted by the same shaft. Therefore, the motor shaft and the pump shaft are configured by the same shaft, the first shaft and the second shaft are configured by the same shaft, and the motor shaft and the output shaft are configured by the same shaft. The configured structure is also included in the present invention including Examples 1 to 4 described below. [0039] Next, the operation will be described. In FIG. 1, the first clutch 14 is released, the second clutch 16 is engaged, and the hydraulic pump / motor 10 is operated as a motor. At this time, the capacity of the hydraulic pump 4 is set to zero capacity, and the capacity of the hydraulic pump motor 10 is set to the maximum capacity.

The hydraulic pump 4 is driven by the drive source 2 via the drive shaft 3. The pressure oil discharged from the hydraulic pump 4 flows into the hydraulic motor 5 and the hydraulic pump 'motor 10 through the oil passage 7 (or the oil passage 8), and drives the hydraulic motor 5 and the hydraulic pump / motor 10. Then, power is output to the output shaft 6 to rotate the output shaft 6. Therefore, as the discharge amount of the hydraulic pump 4 increases, the rotation speed of the output shaft 6 increases. The pressure oil discharged from the hydraulic motor 5 and the hydraulic pump 'motor 10 flows through the oil passage 8 (or the oil passage 7) serving as a discharge passage.

[0041] After the capacity of the hydraulic pump 4 reaches the maximum capacity, the capacity of the hydraulic pump / motor 10 is reduced from the maximum capacity to zero capacity. As a result, the flow rate of the pressure oil flowing into the hydraulic motor 5 is increased, and the rotation of the hydraulic motor 5 and the hydraulic pump motor 10 is further increased. Therefore, the rotational speed of the output shaft 6 further increases.

[0042] After the capacity of the hydraulic pump 'motor 10 reaches zero capacity, the second clutch 16 is released and the first clutch 14 is engaged. As a result, the hydraulic pump 'motor 10 can now act as a pump driven by the drive source 2. When the hydraulic pump motor 10 is operated as a pump, the flow rate of the hydraulic oil supplied to the hydraulic motor 5 can be increased by increasing the capacity of the hydraulic pump motor 10 to the maximum capacity. it can. That is, in addition to the discharge amount of the hydraulic pump 4, the discharge amount from the hydraulic pump / motor 10 can be supplied to the hydraulic motor 5.

[0043] Thereby, the rotational speed of the hydraulic motor 5 can be further increased, and the rotational speed of the output shaft 6 can be further increased. If the swash plate tilt direction in the hydraulic pump 4 is tilted in the direction opposite to the above description, the hydraulic motor 5 may rotate in the direction opposite to the above description to cause the vehicle to travel backward. it can.

Next, the speed change method and operation in the hydraulic drive device will be described with reference to FIGS. In FIG. 2, the horizontal axes are speed command values that are commands for capacity adjustment of the hydraulic pump 4, the hydraulic motor 5, and the hydraulic pump motor 10. The vertical axis of the graph (a) indicates the capacity of the hydraulic motor 5, the vertical axis of the graph (b) indicates the capacity of the hydraulic pump 4, and the graph (c) The vertical axis shows the capacity of the hydraulic pump / motor 10.

[0045] The vertical axis of the graph (d) indicates the total capacity of the hydraulic motor 5 and the hydraulic pump 'motor 10 when operated as a motor. The vertical axis of the graph (e) indicates the rotational speed of the output shaft 6, and the vertical axis of the graph (f) indicates the volumetric efficiency r? In the hydraulic drive device 1.

FIG. 3 shows a control flow of the hydraulic drive device 1. As the speed command value, the operation amount of the speed adjustment operation lever, the rotation speed of the drive source 2, etc. can be used.

[0046] In a stop state in which the vehicle speed of the traveling vehicle is zero, the hydraulic pump 4 in FIG. 1 is in a zero swash plate state, that is, zero capacity. Further, the swash plate angle of the hydraulic pump / motor 10 is in the maximum angle state, that is, the maximum capacity state. Further, in order to make the hydraulic pump motor 10 act as a motor, the first clutch 14 is released and the second clutch 16 is engaged. At this time, as shown in the graph (e), the rotation of the output shaft 6 to the traveling vehicle is in a zero state.

In step 1 in FIG. 3, by increasing the swash plate angle of the hydraulic pump 1 shown in FIG. 1, the capacity of the hydraulic pump 1 is also increased to the maximum capacity Vlmax. At this time, the following description will be made on the assumption that the pressure oil is discharged from the hydraulic pump 1 to the oil passage 7. Since the hydraulic motor 5 has a constant capacity and the swash plate angle of the hydraulic pump motor 10 is maintained at the maximum angle state, the hydraulic motor 5 and the hydraulic pump motor 10 are supplied from the oil path 7 and the oil path 11. Each rotation is controlled by the pressurized oil.

The rotation output from the hydraulic motor 5 drives the output shaft 6 to rotate. At the same time, the rotational output from the hydraulic pump-motor 10 rotationally drives the output shaft 6 connected to the hydraulic motor 5 via the second shaft 10b and the second clutch 16. Therefore, the output shaft 6 is driven by the resultant force of the rotational output from the hydraulic motor 5 and the rotational output from the hydraulic pump / motor 10 and can output a high torque required at the time of running start.

That is, when the vehicle is started up or driven at a low speed, the hydraulic motor 5 can be used and the variable displacement hydraulic pump / motor 10 can be used as a motor. For this reason, a large motor capacity can be obtained, and the driving force output to the output shaft 6 can be increased, so that the vehicle can be accelerated with high torque. [0050] This state can be shown as a section in which the speed command value in FIG. As shown in the graph (b), the capacity of the hydraulic pump 4 increases from zero capacity to the maximum capacity Vlmax. Further, as shown in the graphs (a) and (c), the capacities of the hydraulic motor 5 and the hydraulic pump 'motor 10 are the capacity V2 and the maximum capacity V3max, respectively. The total capacity of the motor is in the V2 + V3max state as shown in graph (d).

[0051] In this section, the rotational speed of the output shaft 6 increases from zero to N1 due to the rotational output from the hydraulic motor 5 and the hydraulic pump / motor 10. The volumetric efficiency at this time increases from zero to r? 2.

In step 2 of FIG. 3, it is determined whether or not the capacity of the hydraulic pump 4 has reached the maximum capacity Vlmax. When the capacity of the hydraulic pump 4 is not the maximum capacity, the capacity of the hydraulic pump 4 is increased. When the capacity of the hydraulic pump 4 reaches the maximum capacity Vlmax, go to step 3.

In step 3 of FIG. 3, the swash plate angle of the hydraulic pump / motor 10 is controlled so that the maximum angular force is also zero. At this time, the flow rate of the pressure oil discharged from the hydraulic pump 4 to the oil passage 7 is constant, but the capacity of the hydraulic pump / motor 10 is controlled to be reduced from the maximum capacity V3max to zero capacity. As a result, the flow rate supplied to the hydraulic motor 5 increases, and the rotation of the output shaft 6 can be increased by further increasing the rotation of the hydraulic motor 5.

Therefore, the vehicle speed of the traveling vehicle further increases. This state can be shown as a section in FIG. 2 where the speed command value of the state force A is in the state B. As shown in the graph (c), the capacity of the hydraulic pump 'motor 10 is reduced from the maximum capacity V3max to zero capacity. Further, as shown in the graphs (a) and (b), the capacity of the hydraulic motor 5 is a constant capacity, and the capacity of the hydraulic pump 4 is maintained at the maximum capacity state.

[0055] As shown in the graph (d), the total capacity of the motor decreases to the state of the state force V2 of V2 + V3max. Further, as shown in the graph (e), the rotational speed of the output shaft 6 increases to N2, and the vehicle speed of the traveling vehicle further increases. Also, as shown in the graph (f), the volumetric efficiency decreases from the r? 2 state to the 7? 0 state.

In step 4 of FIG. 3, it is determined whether or not the capacity of the hydraulic pump / motor 10 has reached zero capacity. When the capacity of the hydraulic pump 'motor 10 is not zero, Reduce pump 10 motor capacity. When the capacity of the hydraulic pump motor 10 reaches zero, go to step 5.

In Step 5 of FIG. 3, the second clutch 16 is disconnected and the first clutch 14 is connected. That is, the first shaft 10 a of the hydraulic pump motor 10 and the drive shaft 3 are connected via the first clutch 14. At this time, the capacity of the hydraulic pump / motor 10 is zero. For this reason, the hydraulic pump 'motor

No output torque is output from 10, and no switching shock occurs due to clutch switching.

Further, since the hydraulic motor 5 transmits the rotational output from the hydraulic motor 5 to the output shaft 6, the torque is not lost to the output shaft 6.

In Step 6 of FIG. 3, the hydraulic pump / motor 10 is caused to function as a pump. Hydraulic pump • Increase the capacity of motor 10 to the maximum capacity V3max with zero capacity. At this time, the flow rate of the pressure oil discharged from the hydraulic pump 4 to the oil passage 7 is constant. However, by controlling the swash plate angle of the hydraulic pump and motor 10 to increase the zero capacity force to the maximum capacity V3max, the hydraulic motor 5 can also be supplied with the hydraulic oil discharged from the hydraulic pump and motor 10, The flow rate of the pressure oil supplied to the hydraulic motor 5 can be increased.

[0059] As a result, the hydraulic pump / motor 10 can be used as a pump together with the hydraulic pump 4, so that a large pump capacity can be obtained. Accordingly, the flow rate of the pressure oil supplied to the hydraulic motor 5 is increased, and the hydraulic motor 5 can be rotated at a higher speed. In this way, the variable displacement hydraulic motor, which has reached zero capacity as in the past, is reused as a hydraulic pump without being discarded. This makes it possible to increase the vehicle traveling speed to a higher speed.

[0060] When the vehicle is traveling at a high speed, the hydraulic pump 4 and the hydraulic pump / motor 10 drive the hydraulic motor 5 in the maximum capacity state, so that high capacity efficiency can be obtained. Further, when the hydraulic pump motor 10 is switched from the motor operation to the pump operation, the displacement of the hydraulic pump / motor 10 is performed in the zero capacity state, so that the switching shock accompanying the switching does not occur.

[0061] Further, when the first clutch 14 and the second clutch 16 are switched, the hydraulic motor 5 The rotation output can be transmitted to the output shaft 6 in advance. As a result, torque is not cut off when the clutch is switched.

For this reason, the torque does not run out even when the clutch is switched during the climbing of the slope. Also, since the clutch is switched when the capacity of the hydraulic pump motor 10 is zero, no switching shock occurs.

[0062] The state of step 6 in FIG. 3 can be indicated by a section in which the speed command value in FIG. As shown in graphs (a) and (b) in this section, the capacities of the hydraulic motor 5 and the hydraulic pump 4 are maintained at the capacity V2 and the maximum capacity Vlmax, respectively. As shown in the graph (c), the capacity of the hydraulic pump motor 10 increases from zero capacity to the maximum capacity V3max. As shown in the graph (d), the capacity of the motor is maintained at the maximum capacity V2 of the hydraulic motor 5 alone.

[0063] Further, as shown in the graph (e), the rotational speed of the output shaft 6 increases from N2 to N3, and the vehicle speed of the traveling vehicle further increases. As shown in graph (f), the volumetric efficiency returns from the state of η 0 to the state of 7-2. When the capacity of the hydraulic pump motor 10 returns to the maximum capacity V3max from the state of step 6 in FIG. 3, the control flow ends.

Accordingly, as shown in the graph (d), the motor capacity is the sum of the motor capacities in the hydraulic motor 5 and the hydraulic pump / motor 10 between the start time and the speed command value A. The value is V2 + V3max. Between the speed command value A and the speed command value B, the capacity of the hydraulic motor 5 alone is V2, and then the capacity state of V2 is maintained.

[0065] As shown in the graph (e), the rotational speed of the output shaft 6 is increased to N1 at the speed command value A by increasing the capacity of the hydraulic pump 4, and at the speed command value B, the speed of the hydraulic pump motor 10 is increased. Increased to N2 due to motor capacity reduction. Furthermore, with the speed command value C, the speed can be increased to N3 as the pump capacity of the hydraulic pump motor 10 that has performed the pump function increases, and the maximum rotational speed can be reached.

[0066] Power at start-up Since the motor capacity can be increased at low speeds, high torque can be output to the output shaft 6. In addition, at high speeds, the speed of the output shaft 6 can be increased to the maximum speed, which makes it possible to drive the traveling vehicle at a high speed. [0067] As shown in the graph (f), in the speed command value A, the volumetric efficiency can be set to r? 2, which is the maximum volumetric efficiency state, as the capacity of the hydraulic pump 4 increases. At the speed command value B, the force decreases by a decrease in the motor capacity of the hydraulic pump 'motor 10 and decreases to 7? 0. At the speed command value C, the pump capacity of the hydraulic pump' motor 10 increases Again, it can recover to 7-2. That is, high volumetric efficiency can be obtained even during high-speed traveling.

[0068] When deceleration control is performed from high speed running, the displacement control method in the hydraulic pump 4, the displacement control method in the hydraulic pump motor 10, and the relationship between the first clutch 14 and the second clutch 16 are described. In this case, the opening methods can be performed by operating them in the order opposite to the order of the methods at the time of acceleration described above. For this reason, the description of the case of deceleration is omitted here.

[0069] The configuration using a fixed capacity type motor as the hydraulic motor 5 has been described with reference to FIG. 1. However, as shown in FIG. 4, the hydraulic motor 5 can be replaced with a fixed capacity type hydraulic motor. A configuration using a variable displacement hydraulic motor can also be adopted. In this case, control after the control pattern and control flow shown in FIGS. 2 and 3 can be further continued.

That is, when the variable displacement hydraulic motor 5 having the maximum capacity V2 as shown in FIG. 4 is used, the capacity of the hydraulic pump / motor 10 acting as a pump is increased to the maximum capacity V3max. Thereafter, it is possible to perform control to reduce the capacity of the hydraulic motor 5 from the maximum capacity V2 state to, for example, a half capacity. Thereby, the vehicle speed of the traveling vehicle can be further increased.

Further, the configuration in which the output shaft is directly connected to the hydraulic motor 5 has been described with reference to FIGS. 1 and 4. As shown in FIG. 5, the output shaft 6 and the motor shaft 5a of the hydraulic motor 5 are It is also possible to adopt a configuration in which a transmission gear device 24 is disposed between them. At this time, the rotation direction of the output shaft 6 is opposite to the rotation direction of the output shaft 6 in FIGS.

[0072] When the rotation direction of the output shaft 6 in FIG. 5 is the same rotation direction as the rotation direction of the output shaft 6 in FIGS. 1 and 4, a gear mounted on the motor shaft 5a An intermediate gear may be interposed between the gear attached to the output shaft 6 and it can. The gear ratio in the transmission gear unit 24 can be set to an appropriate gear ratio including the state of the gear ratio 1.

[0073] When the reduction gear ratio is set as the transmission gear ratio of the transmission gear unit 24, the rotation of the motor shaft 5a can be decelerated and transmitted to the output shaft 6, and high torque is transmitted to the output shaft 6. can do. That is, it is possible to sufficiently supply the output shaft 6 with the high torque required when the vehicle is driven at low speed.

[0074] When the speed increasing ratio is set as the speed ratio of the transmission gear unit 24, the rotation of the motor shaft 5a can be rotated at an increased speed and transmitted to the output shaft 6, and the rotational speed of the output shaft 6 can be increased. The vehicle can be driven at high speed.

In the description of the first embodiment, the swash plate type variable displacement hydraulic pump 4 and the swash plate type variable displacement hydraulic pump motor 10 are used. The present invention can be appropriately selected and implemented even in an apparatus having a similar capacity variable mechanism.

[0076] Further, when a motor capable of variable speed such as an electric motor is used as the drive source 2, or when a constant rotation type drive source 2 is used as shown in FIG. By adopting a configuration in which the clutch 17 is disposed on the drive shaft 3, a configuration using a fixed displacement hydraulic pump 4 ′ instead of a variable displacement hydraulic pump as the hydraulic pump 4 can be achieved.

That is, when a motor capable of variable speed is used as the drive source 2, the rotation speed of the fixed displacement hydraulic pump is continuously increased by variably controlling the output rotation speed from the drive source 2. Speed or deceleration can be controlled. This makes it possible to continuously increase or decrease the discharge amount from the hydraulic pump that is a fixed displacement hydraulic pump.

Further, when the constant rotation type drive source 2 is used as the drive source 2 as shown in FIG. 6 and the clutch 17 is disposed on the drive shaft 3, the clutch 17 is connected and disconnected to be fixed. The speed of the capacity type hydraulic pump 4 'is continuously increased! /, Can be controlled to decelerate.

Therefore, even in the case described above, the discharge amount of the fixed displacement hydraulic pump force can be continuously increased or decreased. That is, the discharge capacity discharged from the hydraulic pump as the fixed displacement hydraulic pump can be continuously controlled between the zero discharge state and the maximum discharge state. [0080] Further, after the vehicle has reached the maximum speed with the clutch 17 and the first clutch 14 engaged and the second clutch 16 disengaged, the second clutch 16 is engaged so that the drive shaft 3 and the output shaft 6 can be directly connected. As a result, the drive source 2 and the output shaft 6 are connected to each other, and higher power transmission efficiency can be obtained.

When the drive shaft 3 and the output shaft 6 are directly connected, the swash plate angles of the hydraulic pump 4 and the hydraulic pump 'motor 10 are set to substantially zero so that no torque is generated, and the hydraulic motor 5 It is necessary to keep both ports in communication.

Further, when the transmission gear devices 22 and 23 are interposed as in the second and third embodiments described below, (d) the motor capacity in FIG. 2 is expressed using the equivalent capacity of the motor. be able to. The equivalent capacity can be obtained by multiplying the capacity of the hydraulic pump or hydraulic pump / motor by the gear ratio of the respective transmission gear unit.

Example 2

Next, a hydraulic drive device lb according to the second embodiment of the present invention will be described with reference to FIG. The hydraulic drive unit lb according to the second embodiment includes a variable displacement hydraulic pump as the hydraulic pump 4 and a variable displacement hydraulic pump as the motor 20. It has become. Further, in FIG. 1 of the first embodiment, a force that uses a fixed displacement hydraulic motor as the hydraulic motor 5 In the second embodiment, a variable displacement hydraulic motor is used as shown in FIG. 4 of the first embodiment. It becomes the configuration used! The other configuration is the same as that of the hydraulic drive device 1 in the first embodiment.

[0083] For this reason, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The hydraulic pump / motor 20 in the second embodiment has a force similar to that of the hydraulic pump / motor 10 in the first embodiment. From the meaning of distinguishing the first embodiment from the second embodiment, the second embodiment will be described. Uses the symbol of the hydraulic pump motor 20. Further, the first shaft and the second shaft, which are the pump's motor shafts connected to the hydraulic pump'motor 20, are referred to by using the symbols of the first shaft 20a and the second shaft 20b.

[0084] In the following description, the description will be focused on parts different from the configuration in the first embodiment. In FIG. 7, a transmission gear device 22 is disposed between the pump shaft 4 a of the hydraulic pump 4 and the first shaft 20 a of the hydraulic pump / motor 20. The transmission gear unit 22 may be configured to increase the rotation of the pump shaft 4a and transmit it to the first shaft 20a, or to reduce the rotation of the pump shaft 4a and transmit it to the first shaft 20a. You can also. Here, a configuration in which the rotation of the pump shaft 4a is decelerated and transmitted to the first shaft 20a is shown.

[0085] The hydraulic drive device la shown in FIG. 7 can be operated in the same manner as the hydraulic drive device 1 described in the first embodiment. That is, with the first clutch 14 disconnected and the second clutch 16 connected, the capacities of the hydraulic pump motor 20 and the hydraulic motor 5 are brought to the maximum capacity state. By increasing the capacity of the state force hydraulic pump 4 to the maximum capacity of zero capacity force, the rotation of the output shaft 6 can be rotated at an increased speed.

[0086] After the capacity of the hydraulic pump 4 reaches the maximum capacity, the capacity of the hydraulic pump motor 20 is reduced to the maximum capacity force zero capacity while maintaining the connected state of the first clutch 14 and the second clutch 16. . By reducing the capacity of the hydraulic pump / motor 20, the flow rate of the pressure oil supplied to the hydraulic motor 5 can be increased. As a result, the output shaft 6 further rotates at a higher speed.

[0087] When the capacity of the hydraulic pump / motor 20 reaches zero, the connection state of the second clutch 16 is disconnected, and the first clutch 14 in the disconnected state is connected. Thereby, the rotation from the drive shaft 3 can be transmitted to the hydraulic pump motor 20 through the transmission gear device 22 and the first shaft 20a.

[0088] Even if the rated rotational speed of the hydraulic pump 4 and the rated rotational speed of the hydraulic pump motor 20 are different, the rated rotational speed can be adjusted by adjusting the reduction ratio of the transmission gear unit 22. The difference can be absorbed.

Switching by the transmission gear device 22 can be performed in a state where the capacity of the hydraulic pump motor 20 is zero. For this reason, it is possible to prevent the occurrence of a shift shock associated with the switching by the transmission gear device 22. That is, the switching can be performed smoothly without a shift shock.

[0090] The hydraulic pump motor 20 connected to the drive shaft 3 acts as a hydraulic pump. By increasing the capacity of the hydraulic pump motor 20 to zero capacity as well as zero capacity Thus, the discharge amount from the hydraulic pump / motor 20 is added to the discharge amount from the hydraulic pump 4 and supplied to the hydraulic motor 5. As a result, the hydraulic motor 5 further rotates at a higher speed, and the output shaft 6 further rotates at a higher speed.

[0091] After the capacity of the hydraulic pump motor 20 reaches the maximum capacity, the output shaft 6 can be rotated at a higher speed by reducing the capacity of the hydraulic motor 5 to, for example, the maximum capacity state force, half capacity, etc. Can do. When the output shaft 6 is decelerating at the time of increased speed rotation, it can be controlled by controlling each of them in the reverse order to that at the time of increased speed rotation described above.

[0092] In FIG. 7, when the first clutch 14 is connected and the second clutch 16 is disconnected, the rotational direction of the pump shaft 4a and the hydraulic pump by using the three gears constituting the transmission gear device 22 A configuration is shown in which the rotation direction of the motor 20 is the same rotation direction. However, when both the tilting / variable displacement hydraulic pump / motor and the tilting / variable displacement hydraulic motor are used as the hydraulic pump motor 20 and the hydraulic motor 5, respectively, even if the same hydraulic circuit is used The rotation direction of the hydraulic pump motor 20 and the hydraulic motor 5 performing the above can be easily reversed from the rotation direction of the hydraulic pump 4 by appropriately selecting the direction in which the angle of the swash plate is swung.

For this reason, the configuration of the transmission gear device 22 may be configured by, for example, two gears. An example in which a variable displacement hydraulic motor is used as the hydraulic motor 5 has been described. However, as described in FIG. 1 of the first embodiment, the hydraulic motor 5 may be configured to use a fixed displacement hydraulic motor. In this case, after returning the capacity of the hydraulic pump motor 20 to the maximum capacity, the capacity of the hydraulic motor 5 cannot be decreased to further increase the rotation speed of the output shaft 6, but the hydraulic motor 5 Can use inexpensive fixed displacement hydraulic motors.

Example 3

Next, a hydraulic drive device lc according to the third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the hydraulic drive device lc has an arrangement configuration in which a transmission gear device 23 is interposed between a hydraulic pump 'variable displacement hydraulic pump as motor 30' and a variable displacement hydraulic motor as hydraulic motor 5. It has become. Further, in FIG. 1 of the first embodiment, the force is a configuration using a fixed displacement hydraulic motor as the hydraulic motor 5. In the same manner as shown in FIG. 4 of the first embodiment, a variable displacement hydraulic motor is used. The other configuration is the same as that of the hydraulic drive device 1 in the first embodiment.

[0094] For this reason, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Note that the hydraulic pump / motor 30 in the third embodiment has a force similar to that of the hydraulic pump / motor 10 in the first embodiment, so that the first embodiment and the third embodiment are distinguished from each other. In this case, the symbol “hydraulic pump motor 30” is used. Further, the first shaft and the second shaft, which are the pump's motor shafts connected to the hydraulic pump'motor 30, are referred to using the symbols of the first shaft 30a and the second shaft 30b.

[0095] In the following description, the description will be focused on parts different from the configuration in the first embodiment.

In FIG. 8, a transmission gear unit 23 is disposed between the second shaft 30 b of the hydraulic pump motor 30 and the output shaft 6 of the hydraulic motor 5. The transmission gear unit 23 may be configured to increase the speed of the rotation of the second shaft 30b and transmit it to the output shaft 6, or to reduce the rotation of the second shaft 30b and transmit it to the output shaft 6. it can. Here, a configuration in which the rotation of the second shaft 30b is decelerated and transmitted to the output shaft 6 will be described.

[0096] The hydraulic drive device lc shown in FIG. 8 can also be operated in the same manner as the hydraulic drive devices 1 and lb described in the first and second embodiments. That is, with the first clutch 14 disconnected and the second clutch 16 connected, the capacities of the hydraulic pump motor 30 and the hydraulic motor 5 are set to the maximum capacity state. By increasing the capacity of the hydraulic pump 4 from the zero capacity to the maximum capacity from this state, the rotation of the output shaft 6 can be rotated at the speed of the rotation stop state force.

[0097] Even if there is a structural difference between the maximum number of rotations that the hydraulic pump / motor 30 can rotate and the maximum number of rotations that the hydraulic motor 5 can rotate, the reduction ratio or By adjusting the speed increasing ratio, the difference in the maximum rotational speed can be adjusted. Further, by using the transmission gear device 23, the rotation ratio can be appropriately selected between the rotation of the hydraulic pump motor 30 and the rotation of the hydraulic motor 5.

[0098] After the capacity of the hydraulic pump 4 reaches the maximum capacity, the capacity of the hydraulic pump 'motor 30 is reduced to the maximum capacity force zero capacity while maintaining the connected state of the first clutch 14 and the second clutch 16. Reduce. By reducing the capacity of the hydraulic pump / motor 30, the flow rate of the pressure oil supplied to the hydraulic motor 5 can be increased. As a result, the output shaft 6 further rotates at a higher speed.

[0099] When the capacity of the hydraulic pump / motor 30 reaches zero, the connection state of the second clutch 16 is disconnected, and the first clutch 14 in the disconnected state is connected. Thereby, the rotation from the drive shaft 3 can be transmitted to the hydraulic pump 'motor 30 via the first shaft 30a. At this time, disconnection from the connection state between the hydraulic pump 'motor 30 and the hydraulic motor 5 and connection between the hydraulic pump' motor 30 and the hydraulic pump 4 should be performed in a state where the displacement of the hydraulic pump 'motor 30 is zero. Can do.

[0100] For this reason, it is possible to prevent a switching shock from occurring when the first clutch 14 and the second clutch 16 are switched. That is, the clutch can be switched smoothly without a switching shock.

[0101] The hydraulic pump 'motor 30 connected to the drive shaft 3 functions as a hydraulic pump. By increasing the capacity of the hydraulic pump / motor 30 to the maximum capacity even with zero capacity, the amount of discharge from the hydraulic pump / motor 30 is added to the amount of discharge from the hydraulic pump 4 and supplied to the hydraulic motor 5. As a result, the hydraulic motor 5 further rotates at a higher speed, and the output shaft 6 further rotates at a higher speed.

[0102] After the capacity of the hydraulic pump motor 30 reaches the maximum capacity, the output shaft 6 can be further rotated at a reduced speed by reducing the capacity of the hydraulic motor 5 to, for example, the maximum capacity state force half state. Can do. When the output shaft 6 is decelerating at the time of increased speed rotation, it can be controlled by controlling each of them in the reverse order to that at the time of increased speed rotation described above.

[0103] Although an example in which a variable displacement hydraulic motor is used as the hydraulic motor 5 has been described, a fixed displacement hydraulic motor can also be used as the hydraulic motor 5 as described in Fig. 4 of the first embodiment. . In this case, after returning the capacity of the hydraulic pump / motor 30 to the maximum capacity, the capacity of the hydraulic motor 5 cannot be reduced to further increase the rotation of the output shaft 6, but the hydraulic motor 5 is inexpensive. A fixed displacement hydraulic motor can be used.

In FIG. 8, when the first clutch 14 is disconnected and the second clutch 16 is connected, the rotation direction of the second shaft 30b and the output shaft 6 are determined using three gears constituting the transmission gear device 23. The direction of rotation is the same The structure which becomes the same rotation direction is shown. However, in the case of using a double tilt / variable displacement hydraulic pump / motor and double tilt / variable displacement hydraulic motor as the hydraulic pump motor 30 and hydraulic motor 5, respectively, the direction in which the angle of the swash plate is swung is changed. By selecting as appropriate, the rotation direction of the hydraulic pump / motor 30 and the rotation direction of the hydraulic motor 5 performing the motor action can be easily set to the opposite rotation directions even in the same hydraulic circuit.

[0105] For this reason, the gear configuration of the transmission gear unit 23 is, for example, a configuration using two gears.

Example 4

Next, a hydraulic drive unit Id according to the fourth embodiment of the present invention will be described with reference to FIG. As the hydraulic drive device Id in the fourth embodiment, a hydraulic pump 'motor 40 as a single tilting / variable displacement hydraulic pump' motor is used, and a switching valve 25 is provided in the first oil passage 11 and the second oil passage 12. It has become the composition. The other configuration is the same as that of the hydraulic drive device 1 in the first embodiment.

[0107] As the hydraulic pump 'motors 10, 20, and 30 shown in the first to third embodiments, by using a bi-tilting' variable displacement hydraulic pump 'motor, the hydraulic pump' motors 10, 20, and 30 are It can be operated as a hydraulic motor and a hydraulic pump, and the rotation control of the output shaft 6 can be performed steplessly.

[0108] In Example 4, instead of using a hydraulic pump 'motor as a double tilting' variable displacement type hydraulic pump 'motor, a single tilting · variable displacement type hydraulic pump · using a motor as both tilting · variable displacement type The same action as when using a hydraulic pump motor is performed. For this reason, the switching valve 25 is disposed in the first oil passage 11 and the second oil passage 12 in accordance with the use of the unidirectionally inclined “variable displacement hydraulic pump” motor.

[0109] Also, the same constituent members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the fourth embodiment, the hydraulic pump 'motor 40 is used as the symbol for the hydraulic pump' motor. In addition, as the first axis and the second axis which are the motor shafts of the hydraulic pump 'pump connected to the motor 40', the symbols of the first shaft 40a and the second shaft 40b are used.

[0110] In the following description, the description will be focused on parts different from the configuration in the first embodiment. To go.

As shown in FIG. 9, the switching valve 25 can be switched at two positions and four ports. In the position D, the port 40c of the hydraulic pump motor 40 can be connected to the oil passage 7 via the oil passage 11a and the oil passage 11. At the same time, the port 40d of the hydraulic pump / motor 40 can be connected to the oil passage 8 via the oil passage 12a and the oil passage 12.

[0111] In the E position, the port 40c of the hydraulic pump / motor 40 can be connected to the oil passage 8 via the oil passage 11a and the oil passage 12. At the same time, the port 40d of the hydraulic pump motor 40 can be connected to the oil passage 7 via the oil passage 12a and the oil passage 11.

[0112] In the following, as the flow of pressure oil when the switching valve 25 is in the D position and the vehicle moves forward, the discharge pressure from the hydraulic pump 4 flows through the oil passage 7 and the hydraulic pump / motor 40 and the oil An example in which the pressure oil supplied to the pressure motor 5 and discharged from the hydraulic pump motor 40 and the hydraulic motor 5 returns to the hydraulic pump 4 through the oil passage 8 will be described as an example.

[0113] One side tilt · Variable displacement hydraulic pump · Hydraulic pump composed of motor · Motor 40 When hydraulic pump · motor 40 is operated as a hydraulic motor, pressure oil is supplied from port 40c and hydraulic pressure When operated as a pump, pressure oil is discharged from the port 40d.

[0114] For this reason, it is necessary to dispose the switching valve 25 to switch the switching valve 25. When the directional control valve 25 is switched to the D position and the hydraulic pump motor 40 is operated as a motor, the port 40c can function as an introduction port for introducing pressure oil, and the port 40d is a discharge port to the oil passage 8. Can function as.

[0115] When the switching valve 25 is switched to the E position and the hydraulic pump / motor 40 is operated as a pump, the port 40c is an introduction port for introducing the pressure oil in the oil passage 8 into the hydraulic pump / motor 40. Can function as The port 40d can function as a discharge port for the pressure oil from the hydraulic pump / motor 40, and the pressure oil discharged from the port 40d can be supplied to the oil passage 7.

Thus, by switching the switching valve 25 without changing the function of the port 40c as the introduction port, it is possible to cause the hydraulic pump motor 40 to act as a motor or to function as a pump. Furthermore, as the configuration of the hydraulic motor 5, as described with reference to FIG. 1 in the first embodiment, a configuration using a fixed capacity hydraulic motor may be used. In this case, after returning the capacity of the hydraulic pump motor 40 to the maximum capacity, the capacity of the hydraulic motor 5 cannot be reduced to further increase the rotation speed of the output shaft 6. An inexpensive fixed displacement hydraulic motor can be used.

Also in the fourth embodiment, when the capacity of the hydraulic pump 'motor 40 is reduced and the capacity becomes zero capacity, the second clutch 16 is disconnected and the hydraulic pump' pump of the motor 40 'motor shaft 4 Ob The connection between the hydraulic motor 5 and the motor shaft 5a can be released. Then, the disconnected first clutch 14 can be connected to connect the pump motor shaft 40 a and the drive shaft 3.

[0118] When the hydraulic pump / motor 40 is switched to the action of the pump as a pump by this switching, the hydraulic pump / motor 40 can be operated in a state where the capacity of the hydraulic pump / motor 40 is zero. For this reason, it is possible to prevent the occurrence of a switching shock associated with the switching, and it is possible to prevent the occurrence of a torque break due to the switching.

[0119] In Examples 1 to 3, if a switching valve as shown in Fig. 9 is arranged between the oil passage 11 and the oil passage 12, the hydraulic pump motors 10, 20, and 30 can be tilted in one direction. Rolling / variable displacement hydraulic pumps and motors can also be used. In the above-described embodiment, the example using the fixed capacity type hydraulic motor as the hydraulic motor and the example using the variable capacity type hydraulic motor have been described. However, as a hydraulic motor, a fixed displacement hydraulic motor and a variable displacement hydraulic motor can be used without being distinguished.

[0120] Further, as the configuration of the hydraulic pump 4, the fixed displacement hydraulic pump is used instead of the variable displacement hydraulic pump, as described in Example 1, when the fixed displacement hydraulic pump is used. A pump can also be used. The use of a fixed displacement hydraulic pump as the hydraulic pump 4 can be suitably applied to the configurations of the second to fourth embodiments.

[0121] In addition, the arrangement of each of the hydraulic pump 4, the hydraulic pump motors 10 to 40, the hydraulic motor 5, the first clutch 14, the second clutch 16, and the transmission gear devices 22 and 23 departs from the spirit of the present invention. As long as they are not, they can be combined with each other. Furthermore, although the description has been made using the configuration in which the output shaft 6 is connected to the hydraulic motor 5, the output shaft 6 is connected to the hydraulic motor. A configuration in which the motor shaft is connected to the five motor shafts via a transmission gear device or the like can also be adopted.

Similarly, the second shafts 10b to 40b of the hydraulic pumps and motors 10 to 40 and the output shaft 6 may be connected via a transmission gear device or the like. The present invention has a configuration in which the output shaft 6 and the motor shaft 5a are connected via a transmission gear device or the like, and a configuration in which the pump 'motor shaft and the output shaft are connected via a transmission gear device or the like. It is included. Industrial applicability

[0123] The present invention can be suitably applied to a hydraulic drive device capable of continuously variable transmission.

Claims

The scope of the claims

[1] a hydraulic pump driven by the drive source;

A hydraulic motor connected in a closed circuit with the hydraulic pump and connected to an output shaft; and a variable capacity hydraulic pump motor connected in a closed circuit in parallel with the hydraulic pump and the hydraulic motor; ,

A first clutch that connects and disconnects the pump shaft of the hydraulic pump and the motor shaft of the variable displacement hydraulic pump 'motor pump';

A hydraulic drive device comprising: a second clutch that connects and disconnects the pump motor shaft and the motor shaft of the hydraulic motor.

[2] a hydraulic pump driven by the drive source;

A transmission gear device disposed at a connecting portion between the pump shaft and the pump motor shaft, and a second clutch for connecting and disconnecting the pump motor shaft and the motor shaft of the hydraulic motor. Hydraulic drive device characterized.

[3] a hydraulic pump driven by the drive source;

A second clutch for connecting and disconnecting the pump motor shaft and the motor shaft of the hydraulic motor; and a transmission gear device disposed at a connection portion between the pump motor shaft and the motor shaft. Hydraulic drive device.

[4] a hydraulic pump driven by the drive source;

The hydraulic pump is connected to the hydraulic pump in a closed circuit and connected to an output shaft, and the hydraulic pump and the hydraulic motor are connected in parallel via a first oil path and a second oil path connected to the closed circuit. Uni-tilt connected to form a closed circuit to the variable displacement hydraulic pump

A switching valve that switches a flow direction of the pressure oil in the first oil passage and the second oil passage, a pump shaft of the hydraulic pump and the one-side tilt, a variable displacement hydraulic pump, a motor pump

A first clutch that connects and disconnects the motor shaft;

2. A hydraulic drive device comprising: a second clutch that connects and disconnects the pump motor shaft and the motor shaft of the hydraulic motor.

[5] a hydraulic pump driven by the drive source;

A hydraulic motor connected in a closed circuit with the hydraulic pump and connected to an output shaft; a variable displacement hydraulic pump 'motor connected in parallel with the hydraulic pump and the hydraulic motor in a closed circuit;

In the speed change method in the hydraulic drive device provided with the second clutch for connecting and disconnecting the pump motor shaft and the motor shaft of the hydraulic motor,

The variable displacement hydraulic pump: a speed change method comprising: disengaging the first clutch and connecting the second clutch when the motor has zero capacity.