JP2007056810A - Swash plate type axial piston pump motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a swash plate type axial piston pump motor of a good self-priming property and capable of preventing the occurrence of cavitation and aeration. <P>SOLUTION: A sucking passage 16 communicating to a sucking port 14a of a valve plate 13 is formed in the casing 2, and an inner space 18 of the casing 2 and the sucking passage 16 are communicated via a communication oil passage 33. A check valve 34 is provided in the communication oil passage 33 to prevent reverse flow of pressurized oil from the sucking passage 16 to the inner space 18. When pressure in the sucking passage 16 is going to be negative by sucking action of a piston 7, the check valve 34 opens and the suction passage 16 is replenished by pressurized oil in the inner space 18. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a swash plate type axial piston pump motor used as a hydraulic pump, a hydraulic motor, or a hydraulic pump motor.

  Conventionally, in an axial piston pump, pressure oil is sucked from a hydraulic oil tank or the like by a suction action by a piston in a cylinder block, that is, an action of increasing the volume of a cylinder chamber by projecting the piston from the inside of the cylinder. It is supplied to the cylinder through. The supplied pressure oil becomes a high pressure state by the compression action of the piston accompanying the rotation of the cylinder block, that is, the action of reducing the volume of the cylinder chamber by the piston entering the inside of the cylinder, and is discharged from the discharge passage. become.

  In the axial piston motor, high-pressure oil is supplied into the cylinder of the cylinder block via the inlet passage to cause the piston to protrude from the cylinder. The cylinder block is rotated by the piston output. The rotation of the cylinder block is taken out by the rotating shaft. Further, in the step of entering the piston into the cylinder, the pressure oil in the cylinder is discharged from the outlet passage.

  In these axial piston pumps and motors, the pressure oil supplied from the suction passage or the inlet passage to the inside of the cylinder must pass through a narrow port that leads to the inside of the cylinder. As the cylinder block rotates at a high speed, the speed of the piston protruding from the inside of the cylinder increases, and the pressure oil pressure in the suction passage or the inlet passage decreases. By these things, it becomes easy to generate | occur | produce cavitation or it becomes easy to generate aeration, and self-priming property will fall.

  In order to improve the self-priming property of the pressure oil into the cylinder, a pump function is provided for a tandem swash plate hydraulic pump (refer to Patent Document 1) in which an impeller constituting an axial flow boost pump is disposed in a casing, and a cylinder block. A high-pressure plunger pump (see Patent Document 2) in which a structure having the structure is formed has been proposed.

  The tandem swash plate hydraulic pump described in Patent Document 1 is shown in FIG. 7 as a conventional example 1 of the present invention in a longitudinal sectional view. As shown in FIG. 7, a pair of pump units 54 </ b> A and 54 </ b> B are provided in the casing 51 so as to be separated from each other in the axial direction. The disc-shaped valve plates 55A and 55B are formed with suction ports 56A and 56B communicating with the suction passages 69A and 69B and discharge ports 57A and 57B communicating with the discharge passages 70A and 70B.

  The cylinder blocks 58A and 58B rotatably provided in the casing 51 are spline-coupled to the rotation shafts 64A and 64B formed at the center thereof, and rotate integrally with the rotation shafts 64A and 64B. The rear end surfaces of the cylinder blocks 58A and 58B are slidably in close contact with the valve plates 55A and 55B.

  The plurality of cylinders 59A and 59B are formed in the axial direction of the cylinder blocks 58A and 58B at equal angular intervals in the circumferential direction of the cylinder blocks 58A and 58B. The cylinders 59A and 59B selectively communicate with the suction ports 56A and 56B and the discharge ports 57A and 57B of the valve plates 55A and 55B via communication ports 60A and 60B that open to the rear end surfaces of the cylinder blocks 58A and 58B. .

  Shoes 62A and 62B sliding on swash plates 63A and 63B are slidably connected to the tip portions of pistons 61A and 61B that reciprocally slide in cylinders 59A and 59B. One end side of the first rotating shaft 64A rotatably supported in the casing 51 via the bearings 65A and 66A protrudes from the front casing 52 and is connected to an engine (not shown). Further, the other end side of the first rotating shaft 64 </ b> A is spline-coupled to the connecting shaft 67.

  The second rotating shaft 64B rotatably supported in the casing 51 via the bearings 65B and 66B protrudes from the rear casing 53 at one end side and is splined to an input shaft of a pilot pump (not shown). Further, the other end side of the second rotating shaft 64B is spline-coupled to the connecting shaft 67. That is, the first rotating shaft 64A and the second rotating shaft 64B are connected via the connecting shaft 67 so as to be integrally rotatable.

  The first suction passage 69A provided in the casing 51 guides the hydraulic oil stored in the oil chamber 68 to the suction port 56A of the pump unit 54A. The second suction passage 69B guides hydraulic oil in the oil chamber 68 to the suction port 56B of the pump unit 54B. The impeller 71 that constitutes the axial flow boost pump 72 together with the connecting shaft 67 rotates in the oil chamber 68 when the pump units 54A and 54B are operated. The hydraulic oil pumped from the oil chamber 68 by the rotation of the impeller 71 can be supplied to the suction ports 56A and 56B of the pump units 54A and 54B through the suction passages 69A and 69B.

  FIG. 8 shows a longitudinal sectional view of a high-pressure plunger pump described in Patent Document 2 as Conventional Example 2 in the present invention. As shown in FIG. 8, a rotating shaft 82 supported by a pair of bearings 86 is disposed in the internal space 87 of the casing 81. A cylinder block 94 is fitted on the rotary shaft 82, and pistons 85 are slidably fitted in the cylinders 90 formed in the cylinder block 94. A shoe 84 slidably connected to the tip of the piston 85 can slide on the swash plate 89.

  A suction port 95 communicating with the internal space 87 of the casing 81 is provided below the casing 81, and a discharge port 88 is provided on the side of the casing 81. An internal space 87 of the casing 81 communicates with the oil chamber 97 and the collection port 96 via multi-port rectangular screws 92 and 93. The collection port 96 and the discharge port 88 communicate with a suction port 83a and a discharge port 83b formed in the valve plate 83, respectively. The suction port 83 a and the discharge port 83 b can selectively communicate with each cylinder 90 formed in the cylinder block 94.

  The multi-mouth rectangular screws 92 and 93 are configured as shown in FIG. That is, a multi-port rectangular screw 92 is formed on the outer periphery of the cylinder block 94. A flange 91 is formed at a portion of the casing 81 facing the cylinder block 94, and a multi-mouth rectangular screw 93 is formed on the inner peripheral surface of the flange 91. The multi-port rectangular screw 92 and the multi-port rectangular screw 93 are formed as reverse screws.

  As a result, the pressure oil supplied from the suction port 95 passes through the internal space 87 of the casing 81, passes between the multi-port rectangular screws 92 and 93, and from the oil chamber 97 and the collection port 96 to the suction port 83 a of the valve plate 83. Can be supplied to. The screw pump action is performed by the multi-port rectangular screws 92 and 93.

  Further, a bypass oil passage 99 is formed between the internal space 87 of the casing 81 and the oil chamber 97, and a check valve 98 is provided in the bypass oil passage 99. The bypass oil passage 99 is formed as an oil passage having a large cross-sectional area.

As a result, when the cylinder block 94 rotates at high speed, pressure oil can be supplied to the collection port 96 by the screw pump action of the multi-port rectangular screws 92 and 93. Further, when the cylinder block 94 rotates at a low speed, the supply of pressure oil by the screw pump action is insufficient, so that the check valve 98 is pushed up from the bypass oil passage 99 by the suction action of the piston 85 and is stored in the internal space 87 of the casing 81. Pressure oil can be sucked into the oil chamber 97.
Japanese Patent Laid-Open No. 11-230027 Microfilm of Japanese Utility Model No. 55-28190 (Japanese Utility Model Application No. 56-132378)

  The tandem swash plate hydraulic pump described in Patent Document 1 is configured to supply hydraulic oil pumped from an oil chamber 68 using an impeller 71 to suction ports 56A and 56B of pump units 54A and 54B. . In order to provide the impeller, a space in the axial direction of the hydraulic pump is required. In addition, a dedicated oil passage for flowing the pressure oil pumped by the impeller must be formed in the casing.

  For this reason, while the axial length of a hydraulic pump becomes long, the casting weight which comprises a casing will increase. Therefore, the axial length dimension, weight, and field area as a hydraulic pump increase. Further, the cost of the hydraulic pump increases.

  In the high-pressure plunger pump described in Patent Document 2, the pressure oil is pumped to the collection port 96 by the screw pump action of the multi-port rectangular screws 92 and 93. For this reason, when the cylinder block 94 is rotated at a high speed, the screw pump action can be effectively operated. However, when the cylinder block 94 is rotated at a low speed, the supply of pressure oil by the screw pump action is insufficient.

In view of this, the high pressure plunger pump disclosed in Patent Document 2 utilizes the suction action of the piston 85 to push up the check valve 98 in the bypass oil passage 99 and suck the pressure oil in the internal space 87 into the oil chamber 97. ing.
For this reason, particularly when the cylinder block 94 rotates at a low speed, the pressure may become negative in the pressure oil supply passages in the multi-port rectangular screws 92 and 93 and the internal space 87 of the casing 81. In such a state, the pressure balance of the piston shoe 84 is lost.

  When the pressure in the internal space 87 of the casing 81 becomes negative, cavitation and aeration are likely to occur in the cylinder. Further, the internal space 87 side of the oil seal disposed between the rotating shaft 82 and the casing 81 becomes negative pressure, and the pressure oil leaks from the oil seal to the outside.

  In the present invention, without increasing the space and weight as a swash plate type axial piston pump motor, it is possible to prevent the suction side supplying pressure oil to the cylinder from becoming negative pressure, and also to generate cavitation and aeration. It is an object of the present invention to provide an axial piston pump / motor that can be prevented and has good self-priming property.

The object of the present invention can be achieved by the inventions described in claims 1 to 3.
That is, a rotary shaft rotatably supported in the casing, a cylinder block that rotates integrally with the rotary shaft, a suction passage provided in the casing, and intermittently communicates with each cylinder of the cylinder block, A swash plate type axial piston pump / motor comprising a valve plate for supplying and discharging pressure oil, wherein the suction passage communicates with a suction port formed in the valve plate. A communication oil passage connecting the suction passage and a check valve is provided in the communication oil passage, and the check valve prevents the flow of pressure oil from the suction passage to the internal space of the casing. It has become the most important feature.

  In the present invention, the main feature is that the configuration of the cylinder block and the configuration of the check valve are respectively identified with respect to the most main configuration.

  In the present invention, when the suction passage provided in the casing is about to become negative pressure, the check valve is opened, and the pressure oil stored in the internal space of the casing can be replenished to the suction passage. Thereby, it can prevent that a suction passage becomes negative pressure, and generation | occurrence | production of aeration and a cavitation can be prevented. Moreover, since the suction passage is not set to a negative pressure, the suction efficiency by the piston can be increased, and the self-priming performance can be improved.

  In the specification, claims and abstract, the meaning of the term suction passage includes the meaning of the suction passage when the swash plate type axial piston pump motor is operated as a pump, and the swash plate type axial piston pump. The meaning of the inlet passage when the motor is operated as a motor is included.

Further, by providing the cylinder block with a pump function, the pressure oil stored in the internal space of the casing can be pumped to the upstream side of the check valve communicating with the internal space of the casing. Furthermore, even when the pressure of the pressure oil stored in the internal space of the casing rises at a low temperature, for example, the check valve can be opened to discharge the pressure oil in the internal space to the suction passage. Thereby, the pressure rise in the internal space of a casing can be prevented.
In this invention, since the set pressure of a check valve can be adjusted with a spring, it can prevent that the internal space of a casing becomes negative pressure.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. As a swash plate type axial piston pump / motor according to the present invention, a single type swash plate type axial piston pump and a swash plate type axial piston motor will be described below as an example. However, the swash plate type axial piston pump / motor according to the present invention can be effectively applied to a single type and a tandem type.

  Further, as the configuration of the swash plate type axial piston pump / motor according to the present invention, in addition to the shape and arrangement configuration described below, if the shape and arrangement configuration can solve the problems of the present invention, Those shapes and arrangement configurations can be employed. For this reason, this invention is not limited to the Example demonstrated below, A various change is possible.

  Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a swash plate type axial piston pump 1 according to the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, and is a cross-sectional view when the capacity of the swash plate type axial piston pump 1 is set to the maximum capacity state.

  As shown in FIG. 1, in the swash plate type axial piston pump 1, the rotating shaft 3 is rotatably supported in the casing body 2a by a bearing 25 that receives a radial force and a thrust force. Further, an oil seal 26 is provided between the front end portion of the rotary shaft 3 and the casing body 2a. A cylinder block 4 having a cylindrical outer shape is fitted on the rotary shaft 3. A plurality of cylinder holes 5 a are formed in parallel with the rotation shaft 3 on the same circumference of the cylinder block 4 with the rotation shaft 3 as the center. The rotating shaft 3 can be rotationally driven by being connected to a driving source such as an engine.

  A piston 7 is slidably accommodated in each cylinder hole 5a. A piston shoe 11 is swingably connected to the tip of each piston 7. The piston shoe 11 slides on the piston sliding surface of the swash plate 10 that swings and rotates by the swing mechanism 20. The sliding direction of the piston shoe 11 is guided by a shoe retainer 15 provided on the swash plate 10.

  As shown in FIG. 2, which is a cross-sectional view taken along the line II-II in FIG. 1, the arcuate convex surface 22 of the swash plate 10 is swingably supported by the arcuate concave surface 21 of the cradle 12 provided on the casing body 2a. By operating the swing mechanism 20 shown in FIG. 1, the angle of the piston sliding surface in the swash plate 10 can be changed. By changing the angle of the piston sliding surface, the capacity of the swash plate type axial piston pump 1 can be changed variably.

  As shown in FIG. 1, between the cylinder block 4 and the rotary shaft 3, the cylinder block 4 is pressed against the valve plate 13, the piston shoe 11 is pressed against the piston sliding surface of the swash plate 10, and A spring 19 is arranged to bias each of them so as not to separate. Thereby, the cylinder block 4 can always slide in the surface contact state with respect to the valve plate 13 fixed to the end cap 2b. The end cap 2b and the casing main body 2a constituting the casing 2 can be fixed together by matching with the end cap mating surface 27, and the internal space 18 can be formed inside the casing 2.

  A port 8 is formed at the bottom of each cylinder hole 5a. Each port 8 can selectively communicate with the suction port 14 a and the discharge port 14 b of the valve plate 13 formed in a semicircular arc shape as the cylinder block 4 rotates. The suction port 14a and the discharge port 14b communicate with a suction passage 16 and a discharge passage 17 formed in the end cap 2b, respectively.

  The internal space 18 of the casing 1 communicates with the suction passage 16 via the communication oil passage 33. The configuration of the communication oil passage 33 will be described with reference to FIG. 3 which is an enlarged view of a portion surrounded by a dotted line in FIG. As shown in FIG. 3, the communication oil passage 33 includes a first oil passage 33a having one end opened in an annular passage 23 formed between the outer peripheral surface of the cylinder block 4 and the inner peripheral surface of the casing body 2a. The other end portion is constituted by a second oil passage opened to the suction passage 16.

  A check valve 34 is disposed between the first oil passage 33a and the second oil passage 33b. As a configuration of the check valve 34, a seat portion 37 having a narrow opening area is formed in the first oil passage 33 a, and the poppet 38 is in pressure contact with the seat portion 37 by a biasing force of a spring 39. The end of the spring 39 is supported by the spring seat 40. The spring sheet 40 side is sealed by the cap 41. The second oil passage 33b is connected to the downstream side of the poppet 38 via an annular groove.

  When the pressure on the first oil passage 33a increases or the pressure on the second oil passage 33b decreases, the poppet 38 is released from the pressure contact state with the seat portion 37 against the biasing force of the spring 39, and the seat portion. It is separated from 37. As a result, the first oil passage 33a and the second oil passage 33b communicate with each other. The operating pressure of the poppet 38 can be adjusted by the set pressure by the spring 39.

  In the illustrated example, a configuration in which the second oil passage is branched from the first oil passage 33 a on the downstream side of the poppet 38, that is, on the suction passage 16 side, is shown. It can also be set as the structure which connected the 2nd oil path. In this case, one end portion of the first oil passage 33a is formed in the vicinity of the abutting portion of the annular passage 23, and the check valve 34 and the second oil passage are disposed so as to extend from the supply oil passage 23. it can. The pressure oil that has passed between the seat portion 37 and the poppet 38 passes through a through-hole formed in the poppet 38, passes through the spring chamber in which the spring 39 is disposed, and the second oil connected in place of the cap 41 through the spring seat 40. It can flow into the path 33b.

  On the outer peripheral portion of the cylinder block 4, a component member having a pump action as shown in FIGS. 4 and 5 is formed. 4 (a) and 4 (b) show a front view and a side view of the cylinder block 4 in which a guide groove 30 inclined obliquely with respect to the rotation axis of the cylinder block 4 is formed on the outer peripheral surface of the cylinder block 4. Yes. 5A and 5B are a front view and a side view of the cylinder block 4 in which a through hole 31 penetrating between the end face side and the outer peripheral surface of the cylinder block 4 is formed in the outer peripheral portion of the cylinder block 4. The figure is shown.

  That is, the longitudinal section in the longitudinal direction of the through hole 31 can be formed in a plane including the rotation axis of the cylinder block 4 as shown in FIG. The through hole 31 may be formed as a hole penetrating between the end face side of the cylinder block 4 and the outer peripheral surface of the cylinder block 4 with a positional relationship inclined obliquely with respect to the rotation axis of the cylinder block 4.

  In addition to the configurations shown in FIGS. 4 and 5, the component member having the pump action formed on the outer peripheral portion of the cylinder block 4 may have the configuration of the multi-port rectangular screw in the above-described Conventional Example 2. In addition, fins or the like that are spiral or inclined with respect to the rotation axis of the cylinder block 4 can be formed on the outer peripheral surface of the cylinder block 4.

  When the constituent members that exhibit these pumping actions are formed on the outer peripheral portion of the cylinder block 4, in order to efficiently perform the pumping action by the cylinder block 4, it is desirable to have the following configuration. That is, the width of the annular passage 23 formed by the outer peripheral surface of the cylinder block 4 and the inner peripheral surface of the casing main body 2a, in other words, the interval between the outer peripheral surface of the cylinder block 4 and the inner peripheral surface of the casing main body 2a is uniform. It is desirable that the gap be formed so that the gap becomes a desired narrow gap. Thus, the pressure oil can be efficiently pumped to the upstream side of the first oil passage 33a by the rotation of the cylinder block 4.

  Next, the operation of the swash plate type axial piston pump will be described with reference to FIG. When the rotating shaft 3 is rotated by driving means such as an engine, the cylinder block 4 rotates integrally with the rotating shaft. When the piston shoe 11 is guided by the shoe retainer 15 and slides on the piston sliding surface of the swash plate 10, the piston 7 slides in the cylinder hole 5a based on the inclination angle of the piston sliding surface. As the piston 7 slides, the volume of the cylinder chamber 5b changes.

  When the volume of the cylinder chamber 5b increases in the piston 7 suction process, the pressure oil from the hydraulic oil tank 43 and the like communicating with the suction passage 16 is sucked into the cylinder chamber 5b through the suction port 14a of the valve plate 13. . The pressure oil sucked into the cylinder chamber 5 b is compressed by the compression stroke of the piston 7 and discharged to the discharge passage 17 through the discharge port 14 b of the valve plate 13. The pressure oil discharged to the discharge passage is supplied to an actuator (not shown).

  When the pressure in the suction passage 16 becomes negative due to the suction process of the piston 7, the pressure contact state between the poppet 38 and the seat portion 37 in the check valve 34 is released, and the pressure oil in the internal space 18 of the casing 2 is released. Can be replenished into the suction passage 16. For this reason, the suction passage 16 can be prevented from becoming negative pressure, and cavitation and aeration caused by the suction passage 16 becoming negative pressure can be prevented.

  Further, the cylinder block 4 is formed with a component having a pumping action as shown in FIGS. 4 and 5, so the upstream side of the first oil passage 33 a in FIG. 3, that is, the internal space of the casing 2. The pressure oil can be pumped to the end portion side of the first oil passage 33a communicating with 18, and the pressure of the pressure oil in the first oil passage 33a can be increased. Thereby, the replenishment of the pressure oil to the suction passage 16 through the communication oil passage 33 can be performed efficiently.

  As shown in FIG. 3, the set pressure of the check valve 34 can be adjusted by the spring force of the spring 39. For this reason, it is possible to prevent the pressure oil in the internal space 18 of the casing 2 from being excessively sucked by the suction action of the piston 7. That is, it is possible to prevent the internal space 18 of the casing 2 from becoming a negative pressure. Thereby, it can prevent that the internal space 18 side of the casing 2 in the oil seal 26 becomes a negative pressure, and the reverse leak in the oil seal 26 can be prevented.

  In the first embodiment, the configuration of the swash plate type axial piston pump has been described. However, a hydraulic pump that supplies pressure oil to the suction passage 16 is disposed between the hydraulic oil tank 43 and the suction passage 16, and the discharge passage is provided. If 17 is configured to communicate with the hydraulic oil tank 43, it can be operated as a swash plate type axial piston motor. Even when operated as a swash plate type axial piston motor, the same effects as described above can be obtained.

  As another embodiment according to the present invention, an example in which the present invention is applied to a swash plate type axial piston motor 45 will be described. In FIG. 6, the longitudinal cross-sectional view of the axial piston motor 45 which concerns on this invention is shown. The axial piston motor 45 will be described by taking a motor capable of forward and reverse rotation as an example. Therefore, the communication passages 33 and 35 are disposed between the internal space 18 of the casing 2 and the inlet (exit) passage 46 and the outlet (inlet) passage 47, respectively. In the communication passages 33 and 35, check valves 34 and 36 having the same configuration as described in the first embodiment are arranged.

  In the specification, claims and abstract, the meaning of the term suction passage includes the meaning of the suction passage when the swash plate type axial piston pump motor is operated as a pump, and the swash plate type axial piston pump. The meaning of the inlet passage when the motor is operated as a motor is included. However, in the description of the second embodiment, in order to distinguish between the pump and the motor so that the contents can be easily understood, the terms of the inlet passage and the outlet passage are used instead of using the term of the suction passage, instead of using the term of the suction passage. It explains by using.

  In FIG. 6, the configuration of the outer peripheral portion that causes the cylinder block 4 to perform pumping is omitted, but the configuration that allows the outer peripheral portion of the cylinder block 4 to perform pumping action as described in the first embodiment. A member is formed. For example, when the axial piston motor 45 is rotated forward, the inlet (exit) passage 46 functions as an oil passage for supplying pressurized oil to the cylinder chamber 5b. However, when the axial piston motor 45 is rotated reversely, the inlet (exit) ) The passage 46 functions as an oil passage for discharging the pressure oil.

  Similarly, for example, when the axial piston motor 45 is rotated forward, the outlet (inlet) passage 47 functions as an oil passage for discharging the pressure oil to the hydraulic oil tank 43, but when the axial piston motor 45 is rotated in the reverse direction, The (exit) passage 46 functions as an oil passage for supplying pressure oil to the cylinder chamber 5b.

  When the inlet (outlet) passage 46 functions as an inlet passage into which pressure oil is introduced, the outlet (inlet) passage 47 functions as an outlet passage for discharging the pressure oil. When the inlet (outlet) passage 46 functions as an outlet passage for discharging pressure oil, the outlet (inlet) passage 47 functions as an inlet passage through which pressure oil is introduced.

  The check valves 34 and 36 respectively disposed in the communication oil passage 33 and the communication oil passage 35 have the same configuration as shown in FIG. That is, the poppet 38 is urged by a set pressure by a spring 39, and the poppet 38 is in pressure contact with the sheet portion 37 by the set pressure.

  When the inlet (outlet) passage 46 functions as a pressure oil supply passage to the cylinder chamber 5b, when the inlet (outlet) passage 46 is likely to be in a negative pressure state, the check valve 34 is opened and the internal space is opened. 18 can be refilled into the inlet (outlet) passage 46. Similarly, when the discharge passage 17 functions as a pressure oil supply passage to the cylinder chamber 5b, when the discharge passage 17 is likely to be in a negative pressure state, the check valve 36 is opened and the pressure in the internal space 18 is increased. Oil can be replenished to the discharge passage 17.

  The present invention can apply the technical idea of the present invention to an apparatus or the like to which the technical idea of the present invention can be applied.

It is a longitudinal cross-sectional view of an axial piston pump. Example 1 It is II-II sectional drawing of FIG. Example 1 It is a principal part enlarged view in FIG. Example 1 It is the front view and side view of a cylinder block. Example 1 It is the front view and side view of a cylinder block in another structure. Example 1 It is a longitudinal cross-sectional view of an axial piston pump. (Example 2) It is a principal part longitudinal cross-sectional view of an axial piston pump. (Conventional example 1) It is a longitudinal cross-sectional view of an axial piston pump. (Conventional example 2) It is a principal part enlarged view of FIG. (Conventional example 2)

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Axial piston pump, 2 ... Casing, 3 ... Rotating shaft, 4 ... Cylinder block, 13 ... Valve plate, 14a ... Suction port, 14b ... Discharge port, 16 ... Suction passage, 17 ... Discharge passage, 18 ... Internal space, 23 ... Annular passage, 26 ... Oil seal, 30 ... Guide groove, 31 ... oblique hole, 34. ..Check valve, 35 ... Communication oil passage, 36 ... Check valve, 45 ... Axial piston motor, 46 ... Inlet (exit) passage, 47 ... Exit (inlet) passage, 51 .... Casing, 54A, 54B ... Pump unit, 55A, 55B ... Valve plate, 56A, 56B ... Suction port, 57A, 57B ... Discharge port, 58A, 58B ... Linda block, 64A ... first rotating shaft, 64B ... second rotating shaft, 67 ... connecting shaft, 68 ... oil chamber, 69A, 69B ... suction passage, 70A, 70B ..Discharge passage, 71 ... impeller, 72 ... axial boost pump, 81 ... casing, 82 ... rotary shaft, 83 ... valve plate, 83a ... suction port, 83b ...・ Discharge port, 87 ... Internal space, 91 ... Tub, 92, 93 ... Multi-port rectangular screw, 94 ... Cylinder block, 95 ... Suction port, 96 ... Collection port, 97: Oil chamber.

Claims (3)

A rotating shaft rotatably supported in the casing;
A cylinder block that rotates integrally with the rotating shaft;
A suction passage provided in the casing;
A valve plate that intermittently communicates with each cylinder of the cylinder block to supply and discharge pressure oil;
With
In the swash plate type axial piston pump motor in which the suction passage communicates with a suction port formed in the valve plate,
Forming a communication oil passage connecting the internal space of the casing and the suction passage;
A check valve is disposed in the communication oil passage,
The swash plate type axial piston pump motor characterized in that the check valve prevents the flow of pressure oil from the suction passage to the internal space of the casing.   2. The swash plate type axial according to claim 1, wherein a structure that functions as a rotary pump that supplies pressure oil to an upstream side of the check valve communicated with an internal space of the casing is formed in the cylinder block. Piston pump / motor. The swash plate type axial piston pump motor according to claim 1 or 2, wherein the check valve is provided with a spring for adjusting a set pressure of the check valve.

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