Swash plate type rotating machine

Abstract

To accurately drive a swash plate by an electric motor, and to rationally improve the stagnation of a lubricant in a reduction gear.SOLUTION: A swash plate type rotating machine having a reduction gear in which an output shaft is connected to a rotating shaft of a swash plate, and an electric motor for driving the reduction gear comprises: a send-out port arranged at a casing; an oil supply port arranged at the reduction gear; an oil supply passage for connecting the send-out port of the casing and the oil supply port of the reduction gear; an oil supply hole connected to the send-out port, and formed at the casing so as to oppose the swash plate; an oil supply piston inserted into the oil supply hole, and supplying the oil in the casing to the reduction gear by moving in the oil supply hole by an inclination of the swash plate; and an oil discharge port arranged at the reduction gear.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a rotating machine used in construction machines such as hydraulic excavators, hydraulic cranes, and wheel loaders, and more particularly to a swash plate type rotating machine in which a swash plate is driven by an electric motor. [Background technology]

[0002] In general, a swash plate type rotary machine changes the volume by tilting a swash plate against the rotating shaft of a cylinder block inside a hollow casing and changing the reciprocating distance of the pistons as the cylinder block rotates. In a pump, the discharge flow rate is increased by increasing the tilt angle (the inclination angle of the swash plate), and in a motor, the output torque is increased by increasing the tilt angle. Some swash plate type rotary machines of this type use an electric motor to drive the swash plate (Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-145851 A Summary of the Invention [Problem to be solved by the invention]

[0004] When driving the swash plate with an electric motor, it becomes possible to finely control the tilt angle, which was difficult with the conventional configuration in which the swash plate was driven hydraulically. However, driving the swash plate requires a large amount of power, and in order to keep the electric motor to a practical size, it is necessary to connect the electric motor to the swash plate via a reduction gear. The reduction gear transmits rotational force by solid contact between gears, so lubricating oil is required.

[0005] In the case of the rotating machine of Patent Document 1, the casing surrounding the cylinder block and the gear box of the reducer are connected by a communication hole, and the insides of the casing and the gear box are filled with oil. However, in this document, the inside of the casing of the rotating machine and the inside of the gear box are simply connected by a communication hole, and the lubricating oil does not flow inside the gear box and remains there.

[0006] An object of the present invention is to provide a swash plate type rotating machine in which the swash plate can be driven with high precision by an electric motor and retention of lubricating oil in the reduction gear can be rationally improved. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a hydraulic oil compressor comprising: a casing; a shaft rotatably provided inside the casing; a cylinder block housed in the casing so as to rotate with the rotation of the shaft and having a cylinder bore extending in an axial direction; a main piston inserted into the cylinder bore so as to be capable of reciprocating motion; a valve plate fixed to the casing so as to be in sliding contact with the cylinder block, the valve plate having an inlet port through which oil flows into the cylinder bore and an outlet port through which oil flows out of the cylinder bore; a shoe connected to the main piston; and a sliding surface against which the shoe slides, the valve plate being supported tiltably relative to the casing via a rotation axis, the tilting causing a piston to rotate when the cylinder block rotates. The present invention provides a swash plate type rotating machine having a swash plate that changes the reciprocating distance of the main piston within the cylinder bore, a reducer whose output shaft is connected to the rotating shaft of the swash plate, and an electric motor that drives the reducer.The swash plate type rotating machine further comprises a delivery port provided in the casing, an oil supply port provided in the reducer, an oil supply passage connecting the delivery port of the casing and the oil supply port of the reducer, an oil supply hole connected to the delivery port and provided in the casing so as to face the swash plate, an oil supply piston that is inserted into the oil supply hole and moves within the oil supply hole as the swash plate tilts, thereby supplying oil from within the casing to the reducer, and an oil drain port provided in the reducer. Effect of the Invention

[0008] According to the present invention, the swash plate can be driven with high precision by the electric motor, and retention of lubricating oil in the reduction gear can be improved rationally. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view showing an overall structure of a hydraulic excavator, which is an example of a construction machine equipped with a swash plate type rotating machine according to a first embodiment of the present invention. [Diagram 2] A diagram showing the main parts of the hydraulic circuit of the hydraulic system of the hydraulic excavator shown in Figure 1. [Diagram 3] FIG. 1 is a partial cross-sectional view including a center line of a shaft and a center line of a rotation axis of a swash plate of a swash plate type rotating machine according to a first embodiment of the present invention. [Figure 4] Cross-sectional view of a swash plate type rotating machine taken along line IV-IV in FIG. 3. [Diagram 5] FIG. 1 is a schematic diagram illustrating a main part of an oil supply mechanism provided in a swash plate type rotating machine according to a first embodiment of the present invention; [Figure 6] FIG. 11 is a schematic diagram illustrating a main part of an oil supply mechanism of a swash plate type rotating machine according to a second embodiment of the present invention; [Figure 7] FIG. 13 is a schematic diagram showing, in partial cross section, a main part of a reducer of a swash plate type rotating machine according to a third embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present invention will be described below with reference to the drawings. A swash plate type rotating machine according to the present invention is used in construction machinery such as hydraulic excavators, hydraulic cranes, and wheel loaders. In the following, an example in which the present invention is applied to a hydraulic pump of a hydraulic excavator will be described, but the substantial configuration is similar when the present invention is applied to a hydraulic pump of other construction machinery or when the present invention is applied to a hydraulic motor.

[0011] First Embodiment -Hydraulic excavator- Fig. 1 is a side view showing the overall structure of a hydraulic excavator, which is an example of a construction machine equipped with a swash plate type rotary machine according to a first embodiment of the present invention. Hereinafter, the left side in Fig. 1 will be referred to as the front side of the hydraulic excavator (strictly speaking, the rotating body). The hydraulic excavator shown in the figure is configured to include a vehicle body 1 and a front working machine 2. The vehicle body 1 is configured from a traveling body 3 and a rotating body 4.

[0012] -Running vehicle- The running body 3 is a foundation structure that enables the hydraulic excavator to travel under its own power. Although a wheel-type running body may be used, the present embodiment illustrates a configuration in which a crawler-type running body is used. The running body 3 includes a track frame 5, an idler (driven wheel) 6, a running drive unit 7, a sprocket (driving wheel) 8, and a track (crawler) 9. The track frame 5 is formed in an H-shape when viewed from above by a center frame 5a and a pair of parallel left and right side frames 5b connected to the center frame 5a. An idler 6 is supported at one end of the front and rear of the left and right side frames 5b, and a sprocket 8 is supported at the other end so as to be freely rotatable. An output shaft of the running drive unit 7 is connected to the rotating shaft of the sprocket 8. The running drive unit 7 is composed of a hydraulic motor for traveling and a reduction gear. A circular track 9 is stretched between the idler 6 and the sprocket 8, and the running body 3 travels under its own power by driving the track 9 with the sprocket 8.

[0013] -Rotating body- The rotating body 4 is provided rotatably on the upper part of the running body 3, and is composed of a rotating frame 10, a driver's cab 11, a counterweight 12, a machine room (engine room) 13, etc. The rotating frame 10 is a base frame of the rotating body 4, and is provided on the upper part of the center frame 5a of the truck frame 5 via a rotating ring 14. A rotating motor (not shown) is mounted on the rotating frame 10 near the rotating ring 14, and the output shaft of the rotating motor meshes with a gear provided on the rotating ring 14, causing the rotating body 4 to rotate relative to the running body 3. Although an electric motor can be used as the rotating motor, a hydraulic motor is used in this embodiment.

[0014] A cab 11 is provided at the front of the revolving frame 10 so as to be located on one side (the left side in this example) in the left-right direction of the front working machine 2. A machine room 13 defined by a bonnet cover is provided behind the cab 11 in the revolving frame 10. A counterweight 12 is attached to the rear end of the revolving frame 10.

[0015] -Front work equipment- The front working machine 2 is attached to the rotating body 4, and is a multi-joint type front working device including a working arm 21, a bucket (attachment) 24, a boom cylinder 25, an arm cylinder 26, and a bucket cylinder 27.

[0016] The working arm 21 includes a boom 22 and an arm 23. The boom 22 is rotatably connected to the front part of the revolving structure 4 in the vertical direction, and the arm 23 is rotatably connected to the tip of the boom 22. The bucket 24 is rotatably attached to the tip of the arm 23. Both ends of the boom cylinder 25 are connected to the revolving structure 4 and the boom 22. Both ends of the arm cylinder 26 are connected to the boom 22 and the arm 23. The bucket cylinder 27 has a base end connected to the arm 23 and a tip end connected to the tip of the arm 23 and the bucket 24 via a link. The boom cylinder 25, the arm cylinder 26, and the bucket cylinder 27 are all hydraulic cylinders.

[0017] -Hydraulic system- Figure 2 is a diagram showing the main parts of the hydraulic circuit of the hydraulic system of the hydraulic excavator shown in Figure 1. In Figure 2, elements that have already been explained are given the same reference numerals as in the previously mentioned drawings, and explanations thereof will be omitted.

[0018] 2 is a device that drives driven members of a hydraulic excavator, and is mainly housed in a machine room 13. The driven members are, for example, a front working implement 2 (a boom 22, an arm 23, and a bucket 24) and a vehicle body 1 (a traveling body 3 and a rotating body 4). This hydraulic system is configured to include a prime mover 15, a hydraulic pump 50, a control valve unit 17, an oil tank 18, various pipes and wiring, etc.

[0019] An engine (internal combustion engine) is used as the prime mover 15, but an electric motor may also be used. The hydraulic pump 50 is a swash plate type (variable volume type) rotary machine that is driven by the prime mover 15 to pressurize oil (hydraulic oil) drawn from the oil tank 18 and discharge it as pressurized oil for driving the hydraulic actuator. Although only one hydraulic pump 50 is shown in Fig. 2, multiple pumps may be provided.

[0020] The control valve unit 17 includes a plurality of directional control valves that control the direction and flow rate of pressure oil from the hydraulic pump 50 to the hydraulic actuators. Each directional control valve that constitutes the control valve unit 17 operates when a spool is driven by a pilot pressure acting on a pressure-receiving chamber in response to an operator's operation. In FIG. 2, only the boom cylinder 25, the arm cylinder 26, and the bucket cylinder 27 are shown as hydraulic actuators, but the control valve unit 17 can also control a traveling hydraulic motor that drives the traveling body 3 and a swing motor that drives the swing body 4 to swing. Return oil from the hydraulic actuators is returned to the oil tank 18 via the control valve unit 17. A relief valve 19 that determines a relief pressure (in other words, the maximum pressure of the discharge pipe 16) is provided in the discharge pipe 16 of the hydraulic pump 50.

[0021] In this embodiment, the swash plate 57 is connected to an electric motor 90 via a reducer 80, and the tilt angle of the hydraulic pump 50 (the tilt angle of the swash plate 57), i.e., the pump volume, is controlled by the electric motor 90. The reducer 80 preferably has a high reduction ratio (for example, several tens or more) relative to its size. As the reducer 80, a reducer using a wave gear, hypocycloid gear, paradox planetary gear, etc. can be used, as well as a reducer in which a normal planetary gear is configured in multiple stages to increase the reduction ratio. The configuration of the hydraulic pump 50 will be described later.

[0022] The electric motor 90 is controlled by a controller 30 in response to various detection values ​​(for example, the discharge pressure of the hydraulic pump 50 and the amount of operation of an operating device (not shown)). The controller 30 is an on-board computer mounted on the hydraulic excavator, and is configured to include, for example, an input interface (such as an AD converter), memory (RAM, ROM, HHD, etc.), a calculation device (such as a CPU), and an output interface (such as a DA converter).

[0023] -Swash plate type rotating machine- Fig. 3 is a partial cross-sectional view including the center line of the shaft of hydraulic pump 50 and the center line of the rotation axis of the swash plate, and Fig. 4 is a cross-sectional view of hydraulic pump 50 taken along line IV-IV in Fig. 3. The cross section shown in Fig. 4 is a cross section perpendicular to the cross section of Fig. 3, taken along the center line of the shaft of hydraulic pump 50. Part 51a (described later) of casing 51 is omitted in Fig. 4.

[0024] The hydraulic pump 50 includes a casing 51, a shaft 52, a cylinder block 53, a main piston 54, a valve plate 55, a shoe 56, a swash plate 57, a reducer 80 (FIG. 2), and an electric motor 90 (FIG. 2).

[0025] The casing 51 is the body (outer shell) of the hydraulic pump 50, and is configured in a box shape by fastening a plurality of parts 51a-51e with bolts, for example. In this embodiment, the casing 51 has openings at both ends of a cylindrical part 51c closed by lid-like parts 51a and 51b, and parts 51d and 51e fitted into openings provided on the sides of the part 51c. The part 51a is provided with an inlet (not shown) and an outlet (not shown) for oil for the hydraulic pump 50. The oil tank 18 (FIG. 2) is connected to the inlet via piping, and the discharge piping 16 (FIG. 2) is connected to the outlet.

[0026] Shaft 52 is rotatably provided inside casing 51. Specifically, shaft 52 passes through inside casing 51, is supported at both ends by shaft bearings 63, 64, and is supported by parts 51a, 51b of casing 51 via shaft bearings 63, 64. Shaft 52 passes through part 51b, swash plate 57, cylinder block 53, and valve plate 55. An output shaft of prime mover 15 is connected to shaft 52.

[0027] The cylinder block 53 is connected to the shaft 52 via splines 66 and is housed in the casing 51, and rotates inside the casing 51 as the shaft 52 rotates. A plurality of cylinder holes 65 are bored in the cylinder block 53 at equal intervals in the circumferential direction centered on the rotation center line C1 of the shaft 52. Each cylinder hole 65 extends parallel to the rotation center line C1 of the shaft 52.

[0028] One end (the left end in FIG. 3) of each of the main pistons 54 is inserted into each of the cylinder holes 65 of the cylinder block 53 so as to be capable of reciprocating motion.

[0029] The valve plate 55 is an annular member and is fixed to the part 51a of the casing 51 by, for example, a knock pin (not shown). An end face on one axial side (the left side in FIG. 3) of the cylinder block 53 comes into contact with the valve plate 55 and rotates and slides. An inlet port 68 and an outlet port 69 are drilled in the valve plate 55. The inlet port 68 and the outlet port 69 are provided in an arc shape along the rotational path of the cylinder bore 65. The inlet port 68 communicates with the inlet of the casing 51 and allows the oil flowing into the cylinder bore 65 to pass through. The outlet port 69 communicates with the outlet of the casing 51 and allows the oil flowing out from the cylinder bore 65 to pass through.

[0030] A plurality of shoes 56 are provided corresponding to the main pistons 54. Each shoe 56 is a member having one side (left end in FIG. 3) formed in a ball joint shape and the other side (right end in FIG. 3) having a sliding surface. The ball joint-shaped part of each shoe 56 is passed through a ring-shaped retainer 72 and connected to the other end (right end in FIG. 3) of the corresponding main piston 54. The shoe 56 can rotate and tilt freely with respect to the main piston 54. The sliding surface of the shoe 56 is in sliding contact with the sliding surface of the swash plate 57 (surface facing the cylinder block 53). The retainer 72 is supported by a retainer guide (bushing) 73 through which the shaft 52 passes. The outer circumferential surface of the retainer guide 73 is formed in a spherical shape, and the spherical surface supports the retainer 72 so that it can swing freely. The retainer guide 73 is attached to a protruding portion protruding opposite the swash plate 57 of the cylinder block 53 via a spring. As a result, the retainer guide 73 presses the retainer 72 toward the swash plate 57 , and the sliding surfaces of the shoes 56 are pressed against the sliding surfaces of the swash plate 57 by the retainer 72 , causing the shoes 56 to slide on the sliding surfaces of the swash plate 57 .

[0031] The swash plate 57 is an element that changes the reciprocating distance of the main piston 54 relative to the cylinder bore 65 to change the volume of the hydraulic pump 50, and is disposed facing the end face on the other side (the right side in FIG. 3) of the cylinder block 53. The surface of the swash plate 57 facing the cylinder block 53 is the sliding surface with which the shoe 56 slides. A pair of rotating shafts 58 offset from the center of gravity of the swash plate 57 toward the cylinder block 53 are integrally connected to the swash plate 57 via bracket parts 59. These rotating shafts 58 are rotatably supported by swash plate bearings 74 attached to parts 51d and 51e of the casing 51, and the swash plate 57 is supported by the rotating shafts 58 to be tiltable relative to the casing 51. The rotation center line C2 (FIG. 3) of the rotating shafts 58 is a line perpendicular to (or parallel to) the rotation center line C1 of the shaft 52. 4 around the rotation center line C2 as the rotary shaft 58 rotates. The swash plate 57 is flat, and the sliding surface along which the shoe 56 slides and the back surface 57a facing away from the sliding surface are flat parallel surfaces. The tilting of the swash plate 57 changes the reciprocating distance of the main piston 54 within the cylinder bore 65 when the cylinder block 53 rotates.

[0032] An electric motor 90 is connected to the rotating shaft 58 on one side of the swash plate 57 via a reduction gear 80. Specifically, an input shaft (not shown) of the reduction gear 80 is connected to an output shaft of the electric motor 90, and the reduction gear 80 is driven by the electric motor 90. An output shaft 81 of the reduction gear 80 is connected to the rotating shaft 58 of the swash plate 57, and the rotational power of the electric motor 90 is transmitted to the rotating shaft 58 via the reduction gear 80 to drive (tilt) the swash plate 57. This changes the tilt angle of the hydraulic pump 50, and the volume changes. To maintain the tilt angle of the swash plate 57, an electromagnetic brake of the electric motor 90 can be used.

[0033] As described above, it is desirable to use a small-sized gear with a large reduction ratio (for example, a reduction ratio of several tens or more) such as a wave gear, hypocycloid gear, paradox planetary gear, etc. for the reducer 80. A small-sized gear with a large reduction ratio can also be obtained by connecting multiple stages of normal planetary gears, and a planetary gear mechanism with multiple stages can also be used as the reducer 80.

[0034] The reduction ratio of the paradox planetary gear is a value obtained by multiplying the first reduction ratio, which is determined by the number of teeth of the sun outer gear and the fixed internal gear, by the second reduction ratio, which is determined by the difference in the number of teeth of the two internal gears. If the first reduction ratio is 1 / 10 and the second reduction ratio is 1 / 12, the reduction ratio of the paradox planetary gear is 1 / 120, which has the advantage of being smaller and having higher torque transmission efficiency than normal planetary gears connected in multiple stages. Even if torque is input to the output shaft side of the paradox planetary gear to drive the input shaft, it is necessary to input an extremely large torque to the output shaft due to the large reduction ratio, and it is difficult to input torque to the output shaft side to drive it. Therefore, when a paradox planetary gear mechanism is adopted for the reducer 80, there is an advantage in that the tilt angle of the swash plate 57 can be maintained even if the electromagnetic brake of the electric motor 90 is omitted due to its characteristics.

[0035] -Oil supply mechanism- The hydraulic pump 50 is driven in a state where the inside of the casing 51 and the gear box (gear chamber) 82 of the reduction gear 80 are filled with oil. The oil filling the casing 51 and the gear box 82 of the reduction gear 80 is hydraulic oil circulating in the oil tank 18 and the hydraulic actuator. The hydraulic pump 50 is provided with an oil supply mechanism 100 (FIG. 4) that supplies oil from the inside of the casing 51 to the inside of the gear box 82 of the reduction gear 80. Although a configuration in which oil flows back and forth between the casing 51 and the reduction gear 80 is also conceivable, in this embodiment, the flow of oil between the casing 51 and the reduction gear 80 is limited to one direction from the casing 51 to the reduction gear 80. The inside of the casing 51 is supplied with oil by oil leaking from a gap between the main piston 54 and the cylinder bore 65, a gap between the valve plate 55 and the cylinder block 53, a gap between the shoe 56 and the swash plate 57, and the like.

[0036] Fig. 5 is a schematic diagram showing the main parts of the oil supply mechanism 100. As can be seen by referring to Fig. 5 together with Figs. 1 to 4, the oil supply mechanism 100 is configured to include a delivery port 101 (Fig. 2), an oil supply port 102 (Fig. 2), an oil supply passage 103, an oil supply hole (oil supply cylinder) 104, an oil supply piston 105, an oil drain port 106 (Fig. 2), and a check valve 107.

[0037] The delivery port 101 is an outlet for delivering the oil inside the casing 51 to the reducer 80, and is provided in a part 51b of the casing 51 facing the rear surface 57a of the swash plate 57.

[0038] The oil supply port 102 is an inlet that receives the oil sent from the casing 51 into the inside of the gear box 82 of the reduction gear 80, and is provided in the gear box 82 of the reduction gear 80.

[0039] The oil supply passage 103 is an oil passage that connects the delivery port 101 of the casing 51 and the oil supply port 102 of the reduction gear 80. The oil supply passage 103 can be formed of a hydraulic hose or a steel pipe.

[0040] The oil supply hole 104 is drilled in the part 51b of the casing 51 so that one end (the left end in FIG. 4) opens facing the back surface 57a of the swash plate 57 and the other end (the right end in FIG. 4) is connected to the delivery port 101 via an appropriate oil passage. At least one oil supply hole 104 may be provided in the casing 51, but FIG. 4 illustrates a configuration in which two oil supply holes 104 are provided. In this embodiment, when viewed from the swash plate 57 in the direction in which the rotation center line C1 of the shaft 52 extends, these two oil supply holes 104 are arranged at symmetrical positions with respect to a plane including the rotation center lines C1 and C2. Therefore, when viewed from the cylinder block 53 in the direction of the swash plate 57, a pair of the oil supply hole 104 and an oil supply piston 105 (described later) exists on both sides of the rotation center line C2. The number of pairs of the oil supply hole 104 and the oil supply piston 105 may be increased to three or more pairs as necessary. When a plurality of sets of oil supply holes 104 and oil supply pistons 105 are provided, for example, oil passages extending from the plurality of oil supply holes 104 join together and are connected to the delivery port 101 .

[0041] The other end (the right end in FIG. 4) of each oil supply piston 105 is inserted into each oil supply hole 104. The oil supply pistons 105 are pushed toward the swash plate 57 by the springs 108 in the oil supply holes 104, and one end (the left end in FIG. 4) of the oil supply pistons 105 is pressed against the back surface 57a of the swash plate 57. The end surface of the oil supply piston 105 pressed against the swash plate 57 is formed as a spherical surface or a curved surface close to a spherical surface. Therefore, the oil supply piston 105 reciprocates along the oil supply hole 104 following the back surface 57a of the tilting swash plate 57, and is driven by the swash plate 57. As a result, when the swash plate 57 moves away from the oil supply hole 104, the oil supply piston 105 is pushed out of the oil supply hole 104 by the spring force, and oil is sucked into the oil supply hole 104 from inside the casing 51 through the gap between the oil supply hole 104 and the oil supply piston 105. Thereafter, when the swash plate 57 approaches the oil feed hole 104, the oil feed piston 105 is pushed into the oil feed hole 104 by the swash plate 57, and the oil inside the oil feed hole 104 is pushed out and supplied to the gear box 82 of the reducer 80 via the oil feed passage 103. In this way, the oil feed piston 105 moves inside the oil feed hole 104 due to the tilting of the swash plate 57, thereby supplying the oil inside the casing 51 to the reducer 80.

[0042] The oil drain port 106 is an outlet for discharging oil displaced from the inside of the gear box 82 of the reducer 80 from the gear box 82, and is provided in the gear box 82 of the reducer 80. This oil drain port 106 is connected to the oil tank 18 via a drain passage 109 (FIG. 2). In this embodiment, as shown in FIG. 2, the drain passage 109 is connected upstream of an oil filter 110 provided in the return piping to the oil tank 18, and the oil drained from the gear box 82 is configured to return to the oil tank 18 via the oil filter 110. Like the oil supply passage 103, the drain passage 109 can be configured by a hydraulic hose or a steel pipe.

[0043] Check valve 107 is a valve that limits the flow direction of oil in oil supply passage 103 to the direction toward reducer 80 (prevents oil from flowing back from gear box 82 of reducer 80 to the inside of casing 51), and is provided in oil supply passage 103. Although a ball check valve is shown as an example of check valve 107 in Fig. 5, the type of check valve 107 can be changed as long as it can perform a backflow prevention function.

[0044] -Operation- When the shaft 52 is driven to rotate by the prime mover 15, the cylinder block 53, the main pistons 54, and the shoes 56 rotate together with the shaft 52 around the rotation center line C1. At that time, each shoe 56 slides on the swash plate 57 inclined with respect to the shaft 52 as shown in FIG. 4, and advances and retreats relative to the cylinder block 53 as it revolves around the rotation center line C1, causing the corresponding main piston 54 to reciprocate inside the cylinder bore 65. Each main piston 54 moves in a direction to be pulled out of the cylinder bore 65 (toward the swash plate 57) when crossing the inlet port 68, and in a direction to be pushed into the cylinder bore 65 (toward the valve plate 55) when crossing the outlet port 69. As a result, the hydraulic pump 50 sucks oil by sucking it into the cylinder bore 65 through the inlet port 68, and discharges the oil through the outlet port 69 by pushing it out of the cylinder bore 65.

[0045] At this time, when the electric motor 90 drives the swash plate 57 to change the tilt angle, the reciprocating distance of the main piston 54 relative to the cylinder bore 65 (that is, the pump volume) changes, and the discharge flow rate of the hydraulic pump 50 changes.

[0046] In this embodiment, the oil supply mechanism 100 operates in accordance with the operation of the swash plate 57. In other words, when the swash plate 57 tilts, the back surface 57a of one side portion approaches the part 51b of the casing 51 with the rotation center line C2 as a boundary, and the back surface 57a of the other side portion moves away from the part 51a. As a result, one oil supply piston 105 is pushed into the oil supply hole 104, and the other oil supply piston 105 is pushed out from the oil supply hole 104. As described above, oil is sucked into the oil supply hole 104 when each oil supply piston 105 is pushed out. The oil sucked into the oil supply hole 104 is pushed out from the oil supply hole 104 when each oil supply piston 105 is pushed in, and is supplied to the gear box 82 of the reducer 80 through the oil supply passage 103. During this time, the check valve 107 prevents the oil from flowing back from the reducer 80 to the casing 51.

[0047] In this embodiment, the hydraulic pump 50 has been described as an example of a swash plate type rotary machine, but it can also be used as a hydraulic motor by feeding oil into the cylinder bore 65 through the inlet port 68. That is, when oil is fed into the cylinder bore 65 through the inlet port 68, the main piston 54 is pushed out of the cylinder bore 65, and the shoe 56 slides along the swash plate 57. This causes the cylinder block 53 to rotate, and the shaft 52 to rotate as an output shaft. The oil fed into the cylinder bore 65 is pushed out of the cylinder bore 65 by the main piston 54 when the cylinder bore 65 crosses the outlet port 69, and is discharged through the outlet port 69. In this case, the oil supply mechanism 100 operates in the same manner.

[0048] -effect- (1) According to this embodiment, the swash plate 57 is driven by the electric motor 90, so that the swash plate 57 can be driven with high precision, and the oil discharge flow rate of the hydraulic pump 50 can be controlled with high precision.

[0049] In addition, as described above, the oil feed piston 105 is interlocked with the swash plate 57, and when the oil feed piston 105 is pushed out from the oil feed hole 104, the oil that flows into the oil feed hole 104 is supplied to the reducer 80 when the oil feed piston 105 is pushed out from the oil feed hole 104. In this way, the movement of the swash plate 57 can be used to supply oil from the casing 51 to the gear box 82 of the reducer 80. Also, the gear box 82 is provided with an oil drain port 106, and as the oil feed piston 105 injects oil from the casing 51 into the reducer 80, excess oil is discharged from the gear box 82 through the oil drain port 106. This allows the oil inside the gear box 82 of the reducer 80 to be sequentially replaced with oil supplied from inside the casing 51. Moreover, oil is not supplied from the casing 51 to the reducer 80 more than necessary, but only when the swash plate 57 is operating, that is, when the reducer 80 is operating, which is rational from the standpoint of reducing energy waste in the oil supply operation and optimizing oil supply opportunities.

[0050] As described above, according to this embodiment, the swash plate 57 can be driven by the electric motor 90 with high precision, and the retention of lubricating oil in the reduction gear 80 can be improved rationally.

[0051] (2) As described above, according to this embodiment, the oil inside the gear box 82 flows and is gradually replaced as the reducer 80 operates, so that a cooling effect for the inside of the gear box 82 can also be expected.

[0052] (3) If the only goal is to prevent oil from accumulating in the reducer 80, it is possible to connect the oil drain port 106 to the casing 51 and return the oil from the reducer 80 to the casing 51, thereby circulating the oil between the casing 51 and the reducer 80. However, inside the gear box 82, wear powder is likely to be generated due to solid contact between the gears, and if the oil is returned from the reducer 80 to the casing 51, there is a risk that the wear powder generated in the reducer 80 will enter the inside of the casing 51 along with the oil.

[0053] Inside the casing 51, there are many sliding points between parts, such as the shoe 56 and the swash plate 57, the main piston 54 and the cylinder bore 65, the cylinder block 53 and the valve plate 55, etc. In order to suppress oil leakage from these points and increase pump efficiency, the gaps between the parts at the sliding points are set as narrow as possible. Therefore, if the oil is returned to the casing 51 from the reducer 80, there is a concern that wear powder that seeps in with the oil from the reducer 80 will get caught between the sliding parts, causing damage to the parts and operational malfunctions, thereby reducing the reliability of the rotating machine.

[0054] In contrast, in this embodiment, the oil drain port 106 of the reducer 80 is connected to the oil tank 18, and consideration is given to preventing wear powder generated in the reducer 80 from entering the casing 51.

[0055] Furthermore, a check valve 107 is provided in the oil supply passage 103 connecting the casing 51 and the reducer 80, and measures are taken to prevent oil from flowing back from the reducer 80 to the casing 51 in the oil supply passage 103. This prevents the oil sent to the reducer 80 from returning to the oil supply hole 104 when the oil supply piston 105 is pushed out from the oil supply hole 104, and also prevents wear powder from flowing into the casing 51 via the oil supply passage 103.

[0056] In this way, backflow of oil that may contain wear powder from the reducer 80 to the casing 51 is suppressed, and wear powder can be prevented from getting caught between the sliding parts inside the casing 51, thereby ensuring high reliability of the hydraulic pump 50.

[0057] In addition, so long as the inflow of wear powder from the reducer 80 into the casing 51 is suppressed, a configuration in which a magnet is provided in the gear box 82 of the reducer 80 to collect the wear powder can be applied in place of or in addition to the check valve 107.

[0058] (4) In this embodiment, the oil supply holes 104 and the oil supply pistons 105 are provided on both sides of the rotating shaft 58 of the swash plate 57, so that oil is sent from the casing 51 to the gear box 82 of the reducer 80 whether the tilt angle is increasing or decreasing. This makes it possible to supply oil to the gear box 82 from one of the oil supply holes 104 every time the gears of the reducer 80 move, which is rational.

[0059] <Second embodiment> Fig. 6 is a schematic diagram showing the main parts of an oil supply mechanism of a swash plate type rotating machine according to a second embodiment of the present invention. In Fig. 6, the same reference numerals as in the above drawings are used for the same or corresponding elements in this embodiment and the first embodiment, and the description thereof will be omitted.

[0060] This embodiment differs from the first embodiment in that a makeup oil passage 121 and a makeup valve 122 are added to the oil supply mechanism 100.

[0061] Make-up oil passage 121 is provided in part 51b of casing 51, and has an inlet opening into the inside of casing 51 separately from oil supply hole 104. This make-up oil passage 121 is connected to a portion of oil supply passage 103 on the upstream side (casing 51 side) of check valve 107, bypassing oil supply hole 104 (for example, in parallel).

[0062] Make-up valve 122 is a check valve provided in makeup oil passage 121, and limits the flow direction of oil in makeup oil passage 121 to the direction toward oil supply passage 103 (prevents oil from flowing back from oil supply passage 103 to casing 51). Although a ball check valve is shown as an example of makeup valve 122 in Fig. 6, the type of makeup valve 122 can be changed as long as it can perform a backflow prevention function.

[0063] In this embodiment, at least one set of the makeup oil passage 121 and the makeup valve 122 is required. When there is only one set of the oil supply hole 104 and the oil supply piston 105, one set of the makeup oil passage 121 and the makeup valve 122 is naturally sufficient. When there are multiple sets of the oil supply hole 104 and the oil supply piston 105, a set of the makeup oil passage 121 and the makeup valve 122 can be provided corresponding to the multiple oil passages connecting from the multiple oil supply holes 104 to the delivery port 101 (FIG. 2). However, when oil passages extending from the multiple oil supply holes 104 join together and connect to the delivery port 101 (FIG. 2), if the makeup oil passage 121 is configured to connect to this joining portion, one set of the makeup oil passage 121 and the makeup valve 122 is sufficient.

[0064] Except for the above points, the configuration of the hydraulic pump 50 of this embodiment, including the other components of the oil supply mechanism 100, is similar to that of the first embodiment.

[0065] In this embodiment, in addition to the same effects as those in the first embodiment, the action of the oil supply piston 105 provides the following effects.

[0066] As already explained, oil is sucked into oil feed hole 104 from inside casing 51 through the gap between oil feed piston 105 and oil feed hole 104. However, if the gap between oil feed hole 104 and oil feed piston 105 is small, it takes time for oil to be sucked into oil feed hole 104. In this case, if the inclination angle of swash plate 57 changes quickly and frequently, oil may not be sucked into oil feed hole 104 in accordance with the movement of swash plate 57, and there is a concern that an appropriate amount of oil may not be supplied to reduction gear 80 when oil feed piston 105 is pushed in.

[0067] Therefore, in this embodiment, a makeup oil passage 121 and a makeup valve 122 are provided so that oil is filled into the oil feed hole 104 via the makeup oil passage 121 when the oil feed piston 105 is pushed out from the oil feed hole 104. As a result, when the oil feed piston 105 is pushed into the oil feed hole 104, the oil filled in the oil feed hole 104 when the oil feed piston 105 is pushed out is supplied to the reducer 80. Therefore, even if the tilt angle changes quickly and frequently, oil can be supplied to the reducer 80 in accordance with the operation of the swash plate 57. Since the makeup valve 122 is provided, the oil filled in the oil feed hole 104 does not return to the inside of the casing 51 via the make-up valve 122 when the oil feed piston 105 is pushed into the oil feed hole 104.

[0068] <Third embodiment> 7 is a schematic diagram showing a partial cross section of a main part of a reducer of a swash plate type rotating machine according to a third embodiment of the present invention. In FIG. 7, elements in this embodiment that are the same as or correspond to those in the first embodiment are given the same reference numerals as those in the previously mentioned drawings, and the description thereof will be omitted.

[0069] The present embodiment differs from the first embodiment in that an oil supply port 102 of the reduction gear 80 opens toward the meshing portion of the gears of the reduction gear 80. In other respects, the present embodiment has the same configuration as the first embodiment.

[0070] As described above, a small gear with a high reduction ratio, such as a wave gear, a hypocycloid gear, or a paradox planetary gear, is preferably used for the reducer 80. In FIG. 7, a wave gear is used for the reducer 80.

[0071] The reducer 80 in FIG. 7 includes an internal gear (external gear) 83, an external gear (internal gear) 84, and a wave generator 85. The internal gear 83 is a rigid ring-shaped gear called a circular spline, and surrounds the outer periphery of the external gear 84. In this embodiment, the internal gear 83 is fixed to a gear box 82. The external gear 84 is a flexible cylindrical gear called a flexspline, and partially meshes with the internal gear 83. In this embodiment, the internal gear 83 is coaxially connected to the output shaft 81. The wave generator 85 is an elliptical part called a wave generator, and is driven by an electric motor 90 to rotate inside the external gear 84.

[0072] 7 , the external gear 84 is pushed outward and deformed by the wave generator 85 rotating inside, meshing with the internal gear 83 only near the major axis of the wave generator 85 and separating from the internal gear 83 in other portions. When the wave generator 85 rotates, the meshing position of the external gear 84 with respect to the internal gear 83 moves in the rotational direction of the wave generator 85. Then, when the wave generator 85 rotates once, the external gear 84 rotates in the opposite direction to the rotational direction of the wave generator 85 relative to the internal gear 83 by an amount equal to the difference in the number of teeth between the internal gear 83 and the external gear 84, and this rotation of the external gear 84 is output as the rotation of the output shaft 81.

[0073] 7, in this embodiment, the oil supply port 102 opens in the axial direction (the axial direction of the internal gear 83 and the external gear 84) toward the meshing portion of the internal gear 83 and the external gear 84. This allows oil to be sprayed from the oil supply port 102 toward the meshing portion of the internal gear 83 and the external gear 84, and wear powder generated at the meshing portion can be removed from the meshing portion early and in a timely manner. The timing at which oil is sprayed from the oil supply port 102 also coincides with the timing at which the internal gear 83 moves relative to the external gear 84, so that wear powder generated at the meshing portion of the internal gear 83 and the external gear 84 can be removed rationally.

[0074] <Modification> Although the configuration in which the spring 108 is used to push the oil feed piston 105 out of the oil feed hole 104 has been exemplified, it is also possible to use a configuration in which the oil feed piston 105 is connected to the swash plate 57 via, for example, a link mechanism. In this case, when the swash plate 57 moves away from the oil feed hole 104, the oil feed piston 105 is pulled out of the oil feed hole 104 by the swash plate 57, and when the swash plate 57 approaches the oil feed hole 104, the oil feed piston 105 is pushed into the oil feed hole 104 by the swash plate 57. [Explanation of symbols]

[0075] 50...hydraulic pump (swash plate type rotating machine), 51...casing, 52...shaft, 53...cylinder block, 54...main piston, 55...valve plate, 56...shoe, 57...swash plate, 58...rotating shaft, 68...inlet port, 69...outlet port, 80...reduction gear, 81...output shaft, 90...electric motor, 101...delivery port, 102...oil supply port, 103...oil supply passage, 104...oil supply hole, 105...oil supply piston, 106...oil drain port, 107...check valve, 121...make-up oil passage, 122...make-up valve, C2...rotation center line

Claims

1. A casing; A shaft rotatably provided inside the casing; a cylinder block that is accommodated in the casing so as to rotate with the rotation of the shaft and has a cylinder bore extending in the axial direction; a main piston inserted in the cylinder bore so as to be capable of reciprocating motion; a valve plate fixed to the casing so that the cylinder block is in sliding contact with the valve plate, the valve plate having an inlet port through which oil flows into the cylinder bore and an outlet port through which oil flows out of the cylinder bore; A shoe connected to the main piston; a swash plate having a sliding surface against which the shoe slides, the swash plate being tiltably supported by the casing via a rotation shaft, the tilting of the swash plate changing a reciprocating distance of the main piston within the cylinder bore when the cylinder block rotates; a reducer having an output shaft connected to a rotating shaft of the swash plate; and an electric motor that drives the reduction gear. a delivery port provided in the casing; an oil supply port provided in the reduction gear; an oil supply passage connecting a delivery port of the casing and an oil supply port of the reducer; an oil supply hole connected to the delivery port and provided in the casing so as to face the swash plate; an oil supply piston that is inserted into the oil supply hole and moves within the oil supply hole as the swash plate tilts, thereby supplying oil within the casing to the reducer; An oil drain port provided in the reducer; A swash plate type rotating machine comprising:

2. 2. The swash plate type rotating machine according to claim 1, a check valve provided in the oil supply passage for limiting the flow direction of oil in the oil supply passage to a direction toward the reducer.

3. 3. The swash plate type rotary machine according to claim 2, a make-up oil passage having an inlet opening inside the casing and bypassing the oil supply hole to connect to the oil supply passage; a makeup valve provided in the makeup oil passage and configured to limit the flow direction of oil in the makeup oil passage to a direction toward the oil supply passage; A swash plate type rotating machine comprising:

4. 2. The swash plate type rotating machine according to claim 1, A swash plate type rotating machine, characterized in that an oil supply port of the reduction gear opens toward a meshing portion of the gears of the reduction gear.

5. 2. The swash plate type rotating machine according to claim 1, A swash plate type rotary machine, characterized in that the oil supply hole and the oil supply piston are provided on both sides of a rotation center line of a rotation shaft of the swash plate when viewed from the cylinder block.

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