JPS6383451A - Hydraulic power transmission - Google Patents

Abstract

PURPOSE:To exhibit designated pressure control by providing a pressure control valve in a casing and a discharge path in a motor cylinder to eliminate the influence of centrifugal force upon the pressure control valve. CONSTITUTION:A communicating path 47 communicating between the first chamber 31a and the second chamber 31b is provided in a spring holding member 35. The first chamber 31a is connected to an oil tank through the first discharge path 48, the second discharge path 49, a pressure control valve 50 and the third discharge path 51. A pressure control valve 50 is disposed on the end wall of a casing half body 1a in a fixed transmission case 1. Accordingly the centrifugal force will not act on the pressure control valve 50, so that the pressure control valve 50 can exhibit a designated performance without the influence of centrifugal force.

Description

Detailed Description of the Invention A0 Objective of the Invention +11 Industrial Field of Application The present invention provides a hydraulic pump and a hydraulic motor that are interconnected to form a hydraulic closed circuit and are accommodated in a casing, and the motor cylinder of the hydraulic motor is , is rotatably supported by the casing, is arranged surrounding the pump cylinder of the hydraulic pump to define an oil-tight chamber between the pump cylinder, and has a manual shaft connected to the pump cylinder that is relatively rotatable. It relates to a hydraulic transmission arranged concentrically within the motor cylinder.

(2) Conventional technology As disclosed in Japanese Patent Application Laid-Open No. 55-91776, an oil-tight chamber surrounding the cylinder and shoe of a hydraulic pump or hydraulic motor is provided, and the pressure in the oil-tight chamber is regulated to a predetermined pressure. It is known to provide a control valve on a distribution plate that is in sliding contact with the cylinder.

When this structure is applied to a hydraulic pump in which the pump cylinders of a hydraulic pump are surrounded by the motor cylinder of a hydraulic motor with an oil-tight chamber defined between them, as disclosed in Japanese Patent Application Laid-Open No. 57-76357, Simply, the pressure control valve is provided on a distribution panel that is integrated with the motor cylinder.

(3) Problems to be solved by the invention However, when the pressure control valve is installed on the distribution panel, it is affected by centrifugal force as the distribution panel rotates, and the pressure control valve may not be able to exhibit the specified performance. There was a possibility that it would not be possible.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a hydraulic transmission device that eliminates the influence of centrifugal force and allows a pressure control valve to exhibit a predetermined performance.

B0 Structure of the Invention (11 Means for Solving Problems According to the present invention, a pressure control valve that opens when the pressure in the oil-tight chamber exceeds a set value is disposed in the casing, and the pressure control valve A discharge passage is provided in the motor cylinder to connect the valve and the oil-tight chamber.

(2) Function Since the casing does not rotate, centrifugal force does not act on the pressure control valve.

(3) Embodiment Hereinafter, an embodiment in which the present invention is applied to a hydraulic continuously variable transmission for a vehicle will be explained with reference to the drawings. First, in FIG. The gear transmission CVT is composed of a constant displacement hydraulic pump P and a variable displacement hydraulic motor M connected to form a hydraulic closed circuit, and has a mission as a casing formed by connecting two case halves 1a and lb. It is housed in case 1.

The hydraulic pump P includes a pump cylinder 4 connected to an input shaft 2 by a spline 3, and a large number of cylinder holes 5, 5, . . . provided in an annular arrangement surrounding the input shaft 2, respectively. A large number of plungers 6 that are slid together
．． 6... is provided. Power from an engine (not shown) is transmitted to the input shaft 2 via a flywheel 7.

On the other hand, the hydraulic motor M includes a motor cylinder 8 disposed so as to concentrically surround the pump cylinder 4 of the hydraulic pump P and rotate relative thereto;
is provided with a large number of motor plungers 10, 10, .

Support shafts 11 and 12 are coaxially protruded from both ends of the motor cylinder 8 in the axial direction, and one support shaft 11 is connected to the end wall of one case half 1a via a needle bearing 13. The other support shaft 12 is supported by the end wall of the other case half 1b via a pole bearing 14, respectively.

The input shaft 2 passes through an end wall of one case half 1a in an oil-tight manner and is arranged concentrically within the support shaft 11. Moreover, a plurality of needle bearings 15 are interposed between the inner surface of the support shaft 11 and the outer surface of the input shaft 2, so that the input shaft 2 and the pump cylinder 4, the support shaft 11 and the motor cylinder 8
It is possible to rotate relative to.

The support shaft 11 functions as an output shaft of the hydraulic motor M, and the mission case 1 is mounted parallel to the support shaft 11.
A forward and reverse gear device G is provided between the support shaft 11 and a subshaft 18 rotatably supported by roller bearings 16 and ball bearings 17 on both end walls.

The reverse gear device G includes a pair of drive gears 19 and 20 fixed to a support shaft II, a driven gear 21 that meshes with one of the drive gears I9 and is rotatably supported on the subshaft 18, and the other drive gear 21. A driven gear 22 rotatably supported on the subshaft 18 in correspondence with the driving gear 20, and the driving gear 20 and the driven gear 2.
2, a driven clutch gear 24 fixed to the subshaft I8 between drive clutch gears 21a and 222, which are integrally provided at opposing parts of both driven gears 21 and 22, respectively; It has a gear wheel 24 and a clutch member 25 for selectively connecting the re-drive clutch members 21a and 22a, and a shift fork 26 is engaged with the clutch member 25 to selectively operate it.

A gear 28 that meshes with an input gear 27 of a differential is integrally provided on the countershaft 18, and the differential ffD is switched between the forward and reverse directions of the vehicle in response to the operation of the clutch member 25. Driven.

In FIG. 2, an oil-tight chamber 31 is defined between the motor cylinder 8 and the pump cylinder 4 of the hydraulic pump P.
A swash plate 32 facing the end face of the pump cylinder 4 is supported inside the motor cylinder 8 within the oil-tight chamber 31 . An annular integral shoe 33 is in sliding contact with the swash plate 32 .

Each plunger 6.6... and the shoe 33 are connected to each other via a connecting rod 44 so as to be able to freely swing.
A presser ring 34 supported by the motor cylinder 8 is in contact with the inner step of the motor cylinder 8 via a roller bearing 42, and the presser ring 34 is provided with a ring that allows movement in the axial direction and prevents relative rotation. Input shaft 2 via spline 36
A spring holder 35 connected to the spring holder 35 abuts. A coil spring 37 surrounding the input shaft 2 is interposed between the spring holder 35 and the pump cylinder 4.
7, the spring holder 35 elastically presses the shoe 33 toward the swash plate 32 via the presser ring 34. Moreover, the spring holder 35 and the presser ring 34 are in contact with each other on a spherical surface, and the spring holder 35 evenly contacts the presser ring 34 to transmit the elastic force of the coil spring 37 to the presser ring 34.

The oil-tight chamber 31 is divided by the shoe 33, the presser ring 34, and the spring holder 35 into a first chamber 31a on the swash plate 32 side and a second chamber 31b on the pump cylinder 4 side.

The inner peripheral side of the sliding surfaces of the swash plate 32 and the shoe 33 faces the first chamber 31a, and lubricating oil leaking from the sliding surfaces flows into the first chamber 31a. Incidentally, in order to achieve lubrication between the swash plate 32 and the shoe 33, an annular hydraulic pocket 38 is provided on the front surface of the shoe 33. Via provided oil holes 39, 40, 41, it communicates with a pump chamber 45 defined between each plunger 6 and the pump cylinder 4. Therefore, the pressure oil in the pump chamber 45 passes through the oil holes 41 and 40.39 to the hydraulic pocket 3.
8. As a result, the shoe 33 and the swash plate 3
2 sliding surfaces are lubricated.

Moreover, at the same time, the hydraulic pressure in the hydraulic pocket 38 exerts pressure on the shoe 33 so as to receive the thrust of the plunger 6, thereby reducing the contact pressure between the shoe 33 and the swash plate 32.

On the other hand, the motor cylinder 8, the swash plate 32, the shoe 33 are
An annular lubrication chamber 43 surrounding the sliding surface is defined by the roller bearing 42, and the lubrication chamber 43 constitutes a part of the second chamber 31a.

In the lubrication chamber 43, pressure oil in the hydraulic pocket 38 is supplied to the shoe 3.
3 and the swash plate 32, and after the leaked oil fills the lubricating chamber 43, it flows through the roller bearing 42 to the second chamber 31b side. Therefore, new lubricating oil is always kept in the lubricating chamber 43, and the oil keeps the sliding surfaces of the shoe 33 and the swash plate 32 on the shoe 3.
3. It is possible to reliably lubricate from the outside.

In addition to the oil from the lubrication chamber 43, leaked oil from the sliding surfaces of the plunger 6 and the cylinder hole 5, as well as the sliding surfaces of the pump cylinder 4 and the distribution board 46 flows into the second chamber 31b.

The spring holder 35 has a first chamber 31a and a second chamber 31b.
A communication path 47 is provided to communicate between the two.

Further, a first exhaust passage 48 communicating with the first chamber 31a is formed between the support shaft 11 of the motor cylinder 8 and the input shaft 2, and this first exhaust passage 48 is connected to a second exhaust passage 49, a pressure control valve 50
It is connected via a third discharge path 51 to an oil tank (not shown) provided at the bottom of the mission case 1 .

In FIG. 3, the pressure control valve 50 includes a bottomed cylindrical spool valve element 52 for switching communication and isolation between the second and third discharge passages 49 and 51, and a spool valve element 52 that is attached in the blocking direction. A spring 53 is provided. A bottomed hole 54 parallel to the input shaft 2 is bored in the end wall of the case half 1a of the mission case 1, and the spool valve body 52 has an oil chamber 55 between it and the closed end of the bottomed hole 54. A bottomed hole 5 is defined.
4. Further, a support member 57 whose movement toward the open end of the bottomed hole 54 is regulated by a retaining ring 56 fitted in the middle of the bottomed hole 54 is inserted into the bottomed hole 54. A spring 53 is interposed between the spool valve body 52 and the spool valve body 52 . Therefore, the spool valve body 5.2 slides due to the balance between the force in the valve opening direction due to the oil pressure in the oil chamber 55 and the force in the valve closing direction due to the spring 53.

The oil chamber 55 includes a second hole bored in the end wall of the case half 1a.
A discharge path 49 is communicated. Also, in the middle of the bottomed hole 54,
An annular groove 58 is provided which can be switched between communicating with and blocking the oil chamber 55 by the spool valve body 52, and a third discharge passage 51 bored in the end wall is communicated with the annular groove 58.

Therefore, the pressure control valve 50 opens when the oil pressure in the oil chamber 55, that is, the oil pressure in the oil-tight chamber 31 becomes larger than the value set by the spring 53, and regulates the oil pressure in the oil-tight chamber 31 to a predetermined value.

At the opposite ends of the pump cylinder 4 and the shoe 33, mutually meshing bevel gears 61, 62 are fixed. These bevel gears 61 and 62 are formed into synchronous gears with the same number of teeth, and when the pump cylinder 4 rotates together with the human power shaft 2, the shoe 33 is driven to rotate synchronously via the bevel gears 61 and 62. . As a result, the plunger 6 running on the upward side of the slope of the swash plate 32 is given a discharge stroke from the swash plate 32 via the connecting rod 44, and the plunger 6 running on the downward side of the slope is given a suction stroke. It will be done.

In the hydraulic motor M, the annular motor swash plate 63 facing the motor cylinder 8 is connected to the annular swash plate holder 6.
4 is fitted. This swash plate holder 64 is integrally equipped with a pair of trunnion shafts 65 that protrude outward from both sides thereof.
These trunnion shafts 65 are pivotally supported by the mission case 1. Therefore, the motor swash plate 63 can tilt around the axis of the trunnion shaft 65 together with the swash plate holder 64.

The tip of each motor plunger 10 is swingably connected to a plurality of motor shoes 66 that are in sliding contact with a motor swash plate 63. Moreover, in order to keep each motor shoe 66 in sliding contact with the motor swash plate 63, a presser plate 67 that presses the back surface of each motor shoe 66 is rotatable by a ring 69 fixed to the swash plate holder 64 with bolts 68. Supported by The connection portion between each motor shoe 66 and each motor plunger 10 penetrates the presser plate 67 at multiple positions in the circumferential direction,
Therefore, the holding plate 67 rotates together with the motor shoe 66.

Each motor shoe 66 is provided with a hydraulic pump 70 on the front surface that slides into contact with the motor swash plate 63.

On the other hand, the closed end of each cylinder hole 9 and each motor plunger 1
A hydraulic chamber 71 defined between the motor plunger 10 and a series of oil holes 7 formed in the motor shoe 66
2.73 to the hydraulic pocket 70. Therefore, the pressure oil in the hydraulic chamber 71 is supplied to the hydraulic pocket 70 through the oil holes 72 and 73, and exerts pressure on the motor shoe 66 so as to receive the protruding thrust of the motor plunger 10.

As a result, the contact pressure between the motor shoe 66 and the motor swash plate 63 is reduced, and the sliding surfaces of the motor shoe 66 and the motor swash plate 63 are lubricated.

A cylindrical partition 74 is fitted onto the inner circumferential surface of the swash plate holder 64 and faces the inner circumferential surface of the presser plate 67 with a small gap therebetween.
A lubrication chamber 75 surrounding the sliding surfaces of the motor shoe 66 and the motor swash plate 63 is defined by the partition wall 74, the swash plate holder 64, and the retainer 67.

Therefore, the pressure oil in each hydraulic pocket 70 constantly leaks through the sliding surfaces of the motor shoe 66 and the motor swash plate 63, and the leaked oil fills the lubrication chamber 75 as lubricating oil and then passes through the presser plate. It leaks from the gaps in various parts around 67. Therefore, new lubricating oil is always kept in the lubricating chamber 75, and the oil is used to make the motor shoe 66 and the motor swash plate 6.
3 can be reliably lubricated from the outside of the motor shoe 66.

In this case, when the pressure in the lubrication chamber 75 approaches the pressure in the hydraulic pocket 70, the fluid support function j of the hydraulic pocket 70 for the motor shoe 66 is lost, so the lubrication chamber 75 maintains a pressure state close to atmospheric pressure while discharging oil. In order to maintain the pressure, the gaps between the various parts around the presser plate 67 are appropriately selected depending on the amount of oil leaking from the hydraulic pocket 70.

A servo motor 81 is provided in the mission case l to tilt and drive the swash plate holder 64, that is, the motor swash plate 63. This servo motor 81 includes a servo cylinder 82 fixed to the mission case 1, and a servo piston 85 that slides on the servo cylinder 82 to partition the inside of the servo cylinder 82 into a left oil chamber 83 and a right oil chamber 84.
The left oil chamber 8 is provided integrally with the servo piston 85.
A piston rod 86 that oil-tightly and movably penetrates the end wall of the three servo cylinders 82, and a servo piston 85.
The tip of the piston loft 86 is slid into the valve hole 87 formed in the piston loft 86, and the right oil chamber 8 of the servo cylinder 82
The pilot valve 88 extends through the end wall of the fourth side in an oil-tight manner and is movable.

The piston rod 86 is connected to the swash plate holder 6 via a pin 89.
4. Further, an oil passage 90 provided in the servo cylinder 82 is always in communication with the left oil chamber 83, and hydraulic pressure supplied from this oil passage 90 acts on the servo piston 85. The right oil chamber 84 is connected to the valve hole 8 in the servo piston 85 and the piston rod 86 in response to the rightward movement of the pilot valve 88.
7, and a passage 9 that communicates the right oil chamber 84 with the left oil chamber 83 in response to leftward movement of the pilot valve 88.
2 are drilled. Further, the valve hole 87 is communicated with an oil tank at the bottom of the mission case 1 via a reflux path 93.

The servo piston 85 is amplified by the hydraulic pressure supplied from the oil passage 90 so as to follow the leftward and rightward movements of the pilot valve 88, thereby moving the swash plate holder 764, that is, the motor swash plate 63 to the maximum tilt position shown in the figure. and a perpendicular position perpendicular to each motor plunger 10. At this time, the motor swash plate 63 gives reciprocating motion to each motor plunger 10 as the motor cylinder 8 rotates, causing it to expand and contract repeatedly, but the stroke of the motor plunger IO depends on the inclination of the motor swash plate 63. It is adjusted steplessly.

A hydraulic closed circuit is formed between the hydraulic pump P and the hydraulic motor M via the distribution panel 46 and the distribution ring 97. Therefore, when the pump cylinder 4 is rotated by the input shaft 2, the pump chamber 4 of the cylinder 5 that accommodates the plunger 6 in the discharge stroke
High-pressure hydraulic oil discharged from the cylinder 5 is fed to the hydraulic chamber 71 of the cylinder hole 9 that accommodates the motor plunger 10 in the expansion stroke.

On the other hand, the hydraulic oil discharged from the hydraulic chamber 71 of the cylinder hole 9 that accommodates the motor plunger 10 in the contraction stroke returns to the pump chamber 45 of the cylinder hole 5 that accommodates the plunger 6 in the suction stroke. During this time, the plunger 10 in the discharge stroke
The reaction torque that is applied to the motor cylinder 8 via the swash plate 32 and the motor plunger 10 on the expansion stroke are applied to the motor swash plate 6.
The motor cylinder 8, that is, the support shaft 11, is rotationally driven by the sum of the reaction torque received from the motor cylinder 8 and the reaction torque received from the motor cylinder 3.

In this case, the motor cylinder 8 relative to the pump cylinder 4
The gear ratio of is given by the following equation.

Rotation speed of motor cylinder 8 Capacity of hydraulic motor M Capacity of hydraulic pump P As is clear from this equation, if the capacity of hydraulic motor M determined by the stroke of motor plunger IO is changed to a value consisting of zero, the gear ratio can be changed from 1 to 1. You can change up to the required value.

The motor cylinder 8 is composed of first to fourth parts 8a to 8d divided in the axial direction. The first portion 8a includes
The support shaft 11 is integrally provided, and the swash plate 32 is connected to the first portion 8.
provided in a. Also, the second third and fourth portions 8b~
A cylinder hole 9 is provided at 8d. The third portion 8C constitutes a distribution board 46, and the fourth portion 8d has a support shaft 1.
2 are provided integrally.

The first and second portions 3a, 3b are connected by a plurality of bolts 98. Also second. 3rd and 4th minute 8b-8
d are integrally connected by a plurality of bolts 101 with knock pins 99 and 100 positioned at their maximum and mutually at their respective joints.

The inner end of the input shaft 2 is supported at the center of the distribution board 46 via a needle bearing 105, and is connected to the pump cylinder 4.
The spring 37 brings the spring 37 into elastic sliding contact with the distribution board 46 .

A bolt 10 is installed on the outer surface side of the end wall of the case half 1b.
6, a support plate 107 is fixed, and a cylindrical fixed shaft 108 that protrudes into the support shaft 12 of the motor cylinder 8 is fixedly connected to the support plate 107. At the inner end of this fixed shaft 108 is a distribution ring 97 that slides into contact with the distribution panel 46.
is eccentrically supported, and the hollow portion 10 provided in the fourth portion 8d of the motor cylinder 8 is
9 is divided into an inner chamber 110 and an outer chamber 111.

On the other hand, the distribution board 46 has a discharge and suction port 112.1.
13 is bored, and its discharge port 112 connects the pump chamber 45 and inner chamber 11 of the plunger 6 during the discharge stroke.
0, and the pump chamber 45 of the plunger 6 in the suction stroke is communicated with the outer chamber 111 by the suction boat 113. In addition, the distribution board 46 has a large number of communication boats 11.4.
, 114 . . . are bored, and each hydraulic chamber 71 of the motor cylinder 8 is communicated with the inner chamber 110 or the outer chamber 111 by these communication boats 114 , 114 .

Therefore, when the pump cylinder 4 rotates, the high-pressure hydraulic oil generated by the discharge stroke of the plunger 6 flows from the discharge boat l12 into the inner chamber 110, and further passes through the communication port 114 communicating with the inner chamber 110 during the expansion stroke. The oil flows into the hydraulic chamber 71 of the motor plunger 10 to apply thrust to the motor plunger 10. On the other hand, the hydraulic oil discharged by the motor plunger 10 in the contraction stroke is returned to the pump chamber 45 of the plunger 6 in the suction stroke via the communication boat 114 and the suction boat 113 that communicate with the outer chamber 111. Power is transmitted from the hydraulic pump P to the hydraulic motor M as described above by the lubrication of the hydraulic oil.

The side wall of the fixed shaft 108 has an inner chamber 110 and an outer chamber 1.
For example, two short-circuit boats 115 that can communicate between the two short-circuit boats 115 are bored, and a cylindrical clutch valve 116 that opens and closes the short-circuit boats 115 is rotatably fitted into the fixed shaft 108. This clutch valve 116 has a valve hole 117 corresponding to the short circuit boat 115 on its side wall near its tip, and an operation connecting portion 119 connected to an operation shaft 118 connected to a clutch control device (not shown) at its base end. It will be done.

When the clutch valve 116 is rotated and the valve hole 117 is fully opened to match the shorting port 115, the clutch is off, and when the valve hole 117 is moved from the shorting port 115 and fully closed, the clutch is on. When the shorting boat 115 is slightly shifted to a half-open state, a half-clutch state is obtained. That is, in the clutch-off state, the hydraulic oil discharged from the discharge boat 112 into the inner chamber 110 is immediately short-circuited to the outer chamber 11 and the suction boat 113 through the short-circuit boat 115, causing the hydraulic motor M to become inoperable, and in the clutch-on state. In this case, the short circuit of the hydraulic oil as described above is prevented, and the hydraulic oil is connected from the hydraulic pump P to the hydraulic motor M.
Circulation of hydraulic oil occurs and normal transmission occurs.

The clutch valve 116 has a built-in hydraulic servo motor 121 operated by a pilot valve 120 , and a valve rod 123 having a smaller diameter than the inner diameter of the clutch valve 116 is provided at the tip of the servo piston 122 . This excuse 123
protrudes into the inner chamber 110, and a closure valve 124 for the discharge port 112 is swingably attached to its tip. By moving the servo piston 122 to the left, the discharge port 112 can be closed by bringing the closing valve 124 into close contact with the distribution board 46. This closing is performed when the motor swash plate 73 is placed in an upright position and the gear ratio is set to 1. This causes the plunger 6 to be hydraulically locked and the air to be removed from the pump cylinder 4 via each plunger 6 and the swash plate 32 to be closed. The motor cylinder 8 can be mechanically driven, and as a result, the thrust of the motor plunger 10 against the motor swash plate 63 disappears, and the loads on the various bearings due to the thrust are removed.

The fixed shaft 108 and the support plate 107 have an oil passage 139 communicating with the inner chamber 11O and an oil passage 14 communicating with the outer chamber 111.
0 is punctured. Further, an oil passage 141 communicating with an oil passage 90 connected to the servo motor 81 is bored in the support plate 107, and a core oil passage 141 and both oil passages 139, 14 are formed in the support plate 107.
．． A switching valve 142 that selectively switches the state of communication with 0 is provided.

This switching valve 142 operates to connect the oil passage 141 with the one of the oil passages 139 and 140 having a higher oil pressure. Therefore, the servo motor 81 for tilting the tongue-to-slope plate 63 of the hydraulic motor M has an inner chamber 110 and an outer chamber 11.
Hydraulic pressure will be supplied from the side with the higher oil pressure.

Pyro valve 88.1 for both servo motors 81 and 121
20, one ends of links 127, 128 are connected, and the other end of the link 127 is interlocked and connected to a rotation shaft 129 rotated by an operation means (not shown). Further, a cam 130 is provided on the rotation shaft 129, and a cam 130 is provided on the rotation shaft 129.
A cam follower 131 that is in sliding contact with the cam 130 is provided at the other end of the cam follower 131 .

As a result, when the servo motor 81 is operated to bring the motor swash plate 63 into the upright state, the servo motor 121
operates to close the discharge boat 112 with the closure valve 124 .

A replenishment pump F is provided on the outside of the end wall of the case half 1a.
will be equipped. This replenishment pump F is driven by the input shaft 2, and pumps up oil from an oil tank (not shown) at the inner bottom of the transmission case 1 to generate hydraulic oil at a constant pressure. And the discharge boat 13 of this supply pump F
6 communicates with an oil passage 137 provided in the input shaft 2, and the oil passage 137 communicates with the inner chamber 110 via a check valve 138, and also communicates with the outer chamber 111 via a reverse valve (not shown). . Therefore, hydraulic pump P and hydraulic motor M
When hydraulic oil leaks from the hydraulic closed circuit between the two, the leakage can be automatically replenished from the replenishment pump F.

Next, the operation of this embodiment will be explained. The oil-tight chamber 3 defined between the pump cylinder 4 and the motor cylinder 8
1 contains oil leaked from the sliding surfaces of the shoe 33 and the swash plate 32, the pump cylinder 4 and the distribution board 46, and the plunger 6 and the cylinder hole 5. The shoe 33 and the pump cylinder 4 are cooled by the sealed oil.

The oil-tight chamber 31 is divided into a first chamber 31a and a second chamber 31b, and only the inner peripheral sides of the sliding surfaces of the shoe 33 and the swash plate 32 are exposed to the first chamber 31a. Therefore, from the sliding surfaces of the shoe 33 and the swash plate 32, the first chamber 31a
The amount of oil leaking to the swash plate is reduced by the action of centrifugal force caused by the rotation of the shoe 33 and the swash plate 32. However, the spring holder 35 is provided with a communication passage 47 that communicates between the first chamber 31a and the second chamber 31b, and the first chamber 31a has a first discharge passage 48, a second discharge passage 49, a pressure control It is connected to an oil tank via a valve 50 and a third discharge path 51.

Therefore, by circulating oil from the second chamber 31b to the first chamber 31a, the inner peripheral sides of the sliding surfaces of the shoes 33 and the swash plate 32 can be sufficiently cooled, and wear and seizure can be prevented. .

Moreover, since the pressure control valve 50 is disposed on the end wall of the casing half 1a of the mission case 1 in a fixed state, centrifugal force does not act on the pressure control valve 50.
It is possible to eliminate the influence of centrifugal force and make the pressure control valve 50 exhibit a predetermined performance.

FIG. 4 shows another embodiment of the present invention, in which a second discharge passage 49 connected to the pressure control valve 50 and a first discharge passage 49 of the oil-tight chamber 31 are shown.
A first discharge path 48' connecting the chamber 31a is connected to the motor cylinder 8.
It is provided on the supporting shaft 11 over the entire axial length.

This embodiment can also provide the same effects as the above-mentioned embodiments.

C0 Effects of the Invention As described above, according to the present invention, a pressure control valve that opens when the pressure inside the oil-tight chamber exceeds a set value is disposed in the casing, and the pressure control valve and the oil-tight chamber are connected. Since the motor cylinder is provided with a discharge passage for tying the pressure control valve, the influence of centrifugal force on the pressure control valve can be eliminated and a predetermined performance can be achieved.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention.
The figure is an overall longitudinal side view, Figure 2 is a partially enlarged view of the hydraulic pump and hydraulic motor, Figure 3 is an enlarged view of the part ■ in Figure 1, and Figure 4
The figure is an enlarged vertical cross-sectional view of a main part of another embodiment of the present invention. 1...Mission case as a casing, 2...
- Input shaft, 4... Pump cylinder, 8... Motor cylinder, 31... Oil tight chamber, 48.48'... Discharge path, 50... Pressure control valve,

Claims (1)

[Claims] A hydraulic pump and a hydraulic motor are housed in a casing and are interconnected to form a closed hydraulic circuit. In a hydraulic transmission device in which an input shaft coupled to a pump cylinder is arranged concentrically within a motor cylinder so as to be relatively rotatable, the pressure inside the oil-tight chamber is A hydraulic transmission device characterized in that a pressure control valve that opens when the pressure exceeds a set value is disposed in the casing, and a discharge passage for connecting the pressure control valve and the oil-tight chamber is provided in the motor cylinder. .