Hydraulic rotary machine

Abstract

The piston pump (100) comprises: a first force applying mechanism (30) which applies force to the inclined plate (8) according to the supplied control pressure; a second force applying mechanism (40) which applies force to the inclined plate (8) in a manner resisting the first force applying mechanism (30); a regulator (50) which controls the control pressure guided to the first force applying mechanism (30) according to the self-pressure of the piston pump (100), and the regulator (50) comprises: an outer spring (51a) and an outer spring (51b). b), which expands and contracts following the tilt of the inclined plate (8); a control slide valve (52), which moves according to the action of the outer spring (51a) and the inner spring (51b), thereby adjusting the control pressure; an auxiliary spring (70), which exerts an action force relative to the control slide valve (52) in a manner of resisting the action of the outer spring (51a) and the inner spring (51b); and an adjustment mechanism (80), which adjusts the action force exerted by the auxiliary spring (70).

Description

Technical Field

[0001] The present invention relates to a hydraulic rotary machine. Background Art

[0002] Japanese Patent Application Laid-Open (JP2008-240518A) discloses a swash plate piston pump equipped with a horsepower control regulator that controls discharge pressure and discharge flow rate to maintain a substantially constant rated horsepower output. This swash plate piston pump includes a small-diameter piston driven in the direction of increasing the tilt angle and a large-diameter piston driven in the direction of decreasing the tilt angle, serving as a tilt actuator for changing the tilt angle of the swash plate.

[0003] The horsepower control regulator includes outer and inner control springs that press a feedback pin, which moves in response to the swash plate, against the swash plate; and a control spool valve that controls the hydraulic pressure directed to the pressure chamber of the large-diameter piston. The outer and inner control springs are sandwiched between the feedback pin and the control spool valve. The control spool valve is slidably mounted within a cylindrical valve housing. Multiple ports formed on the outer periphery of the valve housing communicate with the control spool valve's oil tank or signal pressure port via multiple communication holes formed in the valve housing. Summary of the Invention

[0004] The horsepower control regulator disclosed in Japanese Patent Application Laid-Open (JP2008-240518A) controls the hydraulic pressure directed to the pressure chamber of the large-diameter piston via a control spool valve that moves in response to the forces exerted by the outer and inner control springs. Consequently, the control characteristics of the horsepower control regulator are determined by the forces exerted by the outer and inner control spool valves. In other words, the forces exerted by the outer and inner control springs are set to achieve the desired control characteristics of the horsepower control regulator.

[0005] Here, due to manufacturing errors (dimensional errors) in the control spool, these errors also cause errors in the amount by which the outer and inner control springs are compressed by the control spool and feedback pin, that is, in the forces exerted by the outer and inner control springs. Consequently, the desired control characteristics of the horsepower control regulator cannot be achieved, and sufficient accuracy in horsepower control of the hydraulic rotary machine may not be achieved.

[0006] An object of the present invention is to improve the accuracy of horsepower control in a hydraulic rotary machine.

[0007] According to one embodiment of the present invention, a hydraulic rotary machine includes: a cylinder block that rotates as a drive shaft rotates; a plurality of cylinders formed in the cylinder block and arranged at predetermined intervals in a circumferential direction of the drive shaft; a piston slidably inserted into the cylinder to define a volume chamber within the cylinder; a swash plate that is tiltable and reciprocates the piston so that the volume chamber expands and contracts as the cylinder block rotates; a first urging mechanism that urges the swash plate in response to a supplied control pressure; a second urging mechanism that urges the swash plate in opposition to the first urging mechanism; a regulator that controls the control pressure directed to the first urging mechanism in response to a self-pressure of the hydraulic rotary machine, the regulator including: a urging member that expands and contracts in response to the tilting of the swash plate; a control spool that moves in response to the urging force of the urging member to adjust the control pressure; an auxiliary urging member that exerts a force on the control spool in opposition to the urging force of the urging member; and a regulating mechanism that adjusts the force exerted by the auxiliary urging member. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a cross-sectional view of the hydraulic rotary machine according to the first embodiment of the present invention.

[0009] Figure 2 This is a diagram showing the structure of the regulator of the hydraulic rotary machine according to the first embodiment of the present invention. Figure 1 An enlarged cross-sectional view of part A.

[0010] Figure 3 This is a diagram showing the configuration of a regulator for a hydraulic rotary machine according to a second embodiment of the present invention, corresponding to Figure 2 An enlarged cross-sectional view of .

[0011] Figure 4 It is an enlarged cross-sectional view showing the structure of an adjuster of a hydraulic rotary machine according to a comparative example of the present invention. DETAILED DESCRIPTION

[0012] (First embodiment)

[0013] Hereinafter, a hydraulic rotary machine 100 according to a first embodiment of the present invention will be described with reference to the drawings.

[0014] The hydraulic rotary machine 100 functions as a piston pump. This piston pump rotates the shaft (drive shaft) 1 using external power, reciprocating the piston 5 and supplying hydraulic oil as a working fluid. Furthermore, the hydraulic rotary machine 100 also functions as a piston motor. This piston motor utilizes the fluid pressure of the externally supplied hydraulic oil to reciprocate the piston 5, rotating the shaft 1 and outputting a rotational driving force. The hydraulic rotary machine 100 can function solely as a piston pump or solely as a piston motor.

[0015] In the following description, a case where the hydraulic rotating machine 100 is used as a piston pump is exemplified, and the hydraulic rotating machine 100 is referred to as a “piston pump 100 ”.

[0016] The piston pump 100 is used as a hydraulic supply source for supplying hydraulic oil to an actuator (not shown) such as a hydraulic cylinder that drives a driven object. Figure 1 As shown, the piston pump 100 includes a shaft 1 that is rotated by a power source, a cylinder block 2 that is coupled to the shaft 1 and rotates together with the shaft 1 , and a housing 3 that houses the cylinder block 2 .

[0017] The housing 3 comprises a bottomed, cylindrical housing body 3a and a cover 3b that seals the open end of the housing body 3a and allows the shaft 1 to pass through. The interior of the housing 3 communicates with a fluid tank (not shown) via a drainage passage (not shown). Furthermore, the interior of the housing 3 may also communicate with a suction passage (not shown), described later.

[0018] A power source such as an engine (not shown) is connected to one end 1a of the shaft 1 that protrudes to the outside through the insertion hole 3c of the cover 3b. The end 1a of the shaft 1 is supported in a freely rotatable manner in the insertion hole 3c of the cover 3b by a bearing 4a. The other end 1b of the shaft 1 is accommodated in a shaft receiving hole 3d provided at the bottom of the housing body 3a and is supported in a freely rotatable manner by a bearing 4b. Although not shown in the figure, a rotating shaft (not shown) of another hydraulic pump such as a gear pump (not shown) that is driven by a power source together with the piston pump 100 is coaxially connected to the other end 1b of the shaft 1 so as to rotate together with the shaft 1.

[0019] The cylinder block 2 has a through hole 2a through which the shaft 1 passes, and is spline-coupled to the shaft 1 via the through hole 2a.

[0020] A plurality of cylinders 2b, each having an opening on one end face, are formed in the cylinder body 2, parallel to the axis 1. The cylinders 2b are formed at predetermined intervals in the circumferential direction of the cylinder body 2. A cylindrical piston 5, which defines a volume chamber 6, is inserted into the cylinder 2b for free reciprocation. The top end of the piston 5 protrudes from the opening of the cylinder 2b, and a spherical seat 5a is formed at the top end of the piston 5.

[0021] The piston pump 100 also has: a slipper 7, which is connected to the spherical seat 5a of the piston 5 in a freely rotatable manner and is in sliding contact with the spherical seat 5a; a swash plate 8, which is in sliding contact with the slipper 7 as the cylinder body 2 rotates; and a valve plate 9, which is arranged between the cylinder body 2 and the bottom surface of the shell body 3a.

[0022] The shoe 7 includes a housing portion 7a that accommodates the spherical seat 5a formed at the top end of each piston 5, and a circular flat plate portion 7b that slides against the sliding contact surface 8a of the swash plate 8. The inner surface of the housing portion 7a is spherically formed and slides against the outer surface of the housed spherical seat 5a. This allows the shoe 7 to be angularly displaced in all directions relative to the spherical seat 5a.

[0023] The swash plate 8 is tiltably supported by the cover 3b in order to vary the discharge rate of the piston pump 100. The flat plate portion 7b of the shoe 7 is in surface contact with the sliding contact surface 8a.

[0024] The valve plate 9 is a circular plate member that is in sliding contact with the base end surface of the cylinder block 2 and is fixed to the bottom of the housing body 3a. Although not shown in the figure, the valve plate 9 is formed with an intake port that connects the intake passage formed in the cylinder block 2 to the volume chamber 6, and a discharge port that connects the discharge passage formed in the cylinder block 2 to the volume chamber 6.

[0025] The piston pump 100 further includes a tilting mechanism 20 that tilts the swash plate 8 according to the fluid pressure, and a regulator 50 that controls the fluid pressure introduced into the tilting mechanism 20 according to the tilt angle of the swash plate 8 .

[0026] The tilt mechanism 20 includes a first biasing mechanism 30 that biases the swash plate 8 in a direction that decreases the tilt angle, and a second biasing mechanism 40 that biases the swash plate 8 in a direction that increases the tilt angle. Specifically, the second biasing mechanism 40 biases the swash plate 8 in a manner that opposes the first biasing mechanism 30.

[0027] The first urging mechanism 30 includes a large-diameter piston 32 slidably inserted into a first piston receiving hole 31 formed in the cover 3 b and in contact with the swash plate 8 ; and a control pressure chamber 33 defined within the first piston receiving hole 31 by the large-diameter piston 32 .

[0028] Fluid pressure regulated by the regulator 50 (hereinafter referred to as “control pressure”) is introduced into the control pressure chamber 33. The large-diameter piston 32 urges the swash plate 8 in a direction to reduce the tilt angle by the control pressure introduced into the control pressure chamber 33.

[0029] The second force applying mechanism 40 includes: a small-diameter piston 42 serving as a control piston, which is inserted into a second piston receiving hole 41 formed on the housing body 3a in a freely sliding manner and abuts against the inclined plate 8; and a pressure chamber 43, which is divided into the second piston receiving hole 41 by the small-diameter piston 42.

[0030] The small-diameter piston 42 includes a first sliding portion 42a, a second sliding portion 42b having an outer diameter smaller than that of the first sliding portion 42a, and a stepped surface 42c formed by the difference in outer diameters between the first sliding portion 42a and the second sliding portion 42b.

[0031] The second piston receiving hole 41 has a first receiving portion 41a, which accommodates the sliding first sliding portion 42a of the small-diameter piston 42; a second receiving portion 41b, whose inner diameter is smaller than that of the first receiving portion 41a and accommodates the sliding second sliding portion 42b; and a stepped surface 41c formed by the difference in inner diameter between the first and second receiving portions 41a, 41b. The first receiving portion 41a opens into the housing 3. The outer circumferential surface and stepped surface 42c of the second sliding portion 42b of the small-diameter piston 42 and the inner circumferential surface and stepped surface 41c of the first receiving portion 41a of the second piston receiving hole 41 define a pressure chamber 43. Specifically, the pressure chamber 43 is an annular space formed on the outer circumference of the small-diameter piston 42.

[0032] The discharge pressure (self-pressure) of the pump 100 is constantly directed to the pressure chamber 43 via the discharge pressure passage 10 formed in the housing body 3a. The small-diameter piston 42, receiving the discharge pressure directed to the pressure chamber 43, biases the swash plate 8 in a direction that increases its tilt angle. A stepped surface 42c formed on the outer circumference of the small-diameter piston 42 serves as the pressure-receiving surface of the small-diameter piston 42, which receives the discharge pressure directed to the pressure chamber 43.

[0033] A spring receiving hole 44a is formed in the small-diameter piston 42 at the end opposite the swash plate 8. The spring receiving hole 44a receives one end of the outer spring 51a and the inner spring 51b, described later. Furthermore, a communication hole 44b is formed in the small-diameter piston 42, connecting the spring receiving hole 44a with the interior of the housing 3. Thus, the spring receiving hole 44a and the interior of the second piston receiving hole 41 communicate with the fluid tank via the communication hole 44b and the interior of the housing 3.

[0034] The large-diameter piston 32 has a larger pressure-receiving area for the control pressure than the small-diameter piston 42. Figure 1As shown, the large-diameter piston 32 is provided on the opposite side of the small-diameter piston 42 relative to the swash plate 8. That is, the large-diameter piston 32 is arranged so that its circumferential position relative to the central axis of the shaft 1 substantially coincides with that of the small-diameter piston 42.

[0035] The regulator 50 adjusts the control pressure introduced into the control pressure chamber 33 according to the discharge pressure of the piston pump 100 , thereby controlling the horsepower (output) of the piston pump 100 .

[0036] The regulator 50 includes: an outer spring 51a and an inner spring 51b as biasing members, which bias the small-diameter piston 42 toward the swash plate 8; a control slide valve 52, which moves according to the biasing force of the outer spring 51a and the inner spring 51b and adjusts the control pressure; an auxiliary spring 70 as an auxiliary biasing member, which exerts a biasing force on the control slide valve 52 in a manner that resists the biasing force exerted by the outer spring 51a and the inner spring 51b on the control slide valve 52; an adjustment mechanism 80, which adjusts the biasing force exerted by the auxiliary spring 70; and a limiter 90, which limits the movement of the control slide valve 52 above a predetermined level due to the biasing force of the outer spring 51a and the inner spring 51b.

[0037] The outer spring 51a and inner spring 51b are each coil springs that expand and contract to follow the tilt of the swash plate 8. The inner spring 51b has a smaller winding diameter than the outer spring 51a and is located inside the outer spring 51a. One end of each of the outer and inner springs 51a and 51b is accommodated in the spring receiving hole 44a of the small-diameter piston 42 and seated on the bottom of the spring receiving hole 44a via a spring seat 72. The other end of each of the outer and inner springs 51a and 51b is seated on the end surface of the control spool 52 via a spring seat 73. One spring seat 72 moves with the small-diameter piston 42, while the other spring seat 73 moves with the control spool 52.

[0038] In the state where the tilt angle of the swash plate 8 is the maximum ( Figure 1 In the state shown in FIG, the other spring seat 73 is not in contact with the bottom of the second housing portion 41b of the second piston housing hole 41, but is separated from the bottom of the second housing portion 41b and floats.

[0039] The natural length (free length) of the outer spring 51a is longer than the natural length of the inner spring 51b. Figure 1 In the state shown in FIG. 1 , the outer spring 51a is compressed by the spring seat 72, while the inner spring 51b is compressed by one end from the spring seat (in FIG. 1 ). Figure 1(The figure shows the spring seat 72) separated and floating (at its natural length). Specifically, as the tilt angle of the swash plate 8 decreases from its maximum position, initially only the outer spring 51a is compressed. As the length of the outer spring 51a is compressed to exceed the natural length of the inner spring 51b, both the outer spring 51a and the inner spring 51b are compressed. This structure allows the elastic force applied to the swash plate 8 by the outer and inner springs 51a, 51b, via the small-diameter piston 42, to gradually increase.

[0040] The housing body 3a includes a spool-receiving hole 50a into which a control spool 52 is slidably inserted. The spool-receiving hole 50a is coaxial with the second piston-receiving hole 41 that receives the small-diameter piston 42 and is connected to the second piston-receiving hole 41 (more specifically, the second receiving portion 41b).

[0041] The housing body 3a also includes a discharge pressure passage 10 that guides the discharge pressure of the piston pump 100, and a control pressure passage 11 that guides the control pressure to the control pressure chamber 33 of the large-diameter piston 32. The discharge pressure of the piston pump 100 is constantly guided through the discharge pressure passage 10. The control pressure passage 11 communicates with the control pressure chamber 33 via a cover-side passage (not shown) formed in the cover 3b.

[0042] The spool valve receiving hole 50 a opens at the end surface of the housing body 3 a . The opening of the spool valve receiving hole 50 a relative to the end surface of the housing body 3 a is closed by a cover 85 .

[0043] like Figure 2 As shown, the cover 85 is formed with a recess 86 that accommodates one end of the control spool valve 52. The recess 86 includes a first recess 86a; a second recess 86b, whose inner diameter is larger than that of the first recess 86a; and a third recess 86c, whose inner diameter is larger than that of the second recess 86b. The difference in inner diameters between the first and second recesses 86a, 86b, forms a first recess step surface 86d. The difference in inner diameters between the second and third recesses 86b, 86c, forms a second recess step surface 86e. The third recess 86c faces the end surface of the housing body 3a.

[0044] The control spool valve 52 includes: a main body portion 53, which is in sliding contact with the inner peripheral surface of the spool valve receiving hole 50a; a flange portion 54, which is provided at one end of the main body portion 53 and has an outer diameter larger than that of the main body portion 53; and a protrusion 55, which is provided at the other end of the main body portion 53 on the opposite side to the flange portion 54 and is inserted into the spring seat 73.

[0045] The flange 54 is received in the third recess 86c of the cover 85. The outer diameter of the protrusion 55 is smaller than that of the main body 53. The step surface 55a formed by the difference in outer diameter between the main body 53 and the protrusion 55 contacts the spring seat 73.

[0046] A first control port 56a and a second control port 56b are formed as annular grooves on the outer circumference of the control spool 52. Furthermore, a first control passage 57a communicating with the first control port 56a and a second control passage 57b communicating with the second control port 56b are formed in the control spool 52 so as to penetrate the control spool 52 in the radial direction.

[0047] The control spool valve 52 is formed with an axial passage 58a and a shaft insertion hole 58b. The axial passage 58a is provided axially from one end (the protrusion 55), while the shaft insertion hole 58b is provided axially from the other end (the flange 54) and is inserted into the shaft 78, described later. The axial passage 58a connects the first control passage 57a with the connecting passage 73a, which is formed in the spring seat 73 and communicates with the spring receiving hole 44a (the second piston receiving hole 41). The shaft insertion hole 58b communicates with the second control passage 57b.

[0048] Thus, the first control passage 57a communicates with the interior of the housing 3 via the axial passage 58a, the connecting passage 73a of the spring seat 73, the spring receiving hole 44a of the small-diameter piston 42, and the communicating hole 44b.

[0049] The stopper 90 includes: a cylindrical first stopper portion 90a, which is inserted into the second recess 86b of the recess 86 of the cover 85; and a second stopper portion 90b, which is inserted into the third recess 86c of the recess 86 of the cover 85 and has an outer diameter larger than that of the first stopper portion 90a. A central hole 90c is formed in the stopper 90 along the axial direction and passes through the axis. Figure 1 In the illustrated state where the tilt angle of the swash plate 8 is at its maximum, the flange portion 54 of the control spool 52 abuts the end surface of the second stopper portion 90b of the stopper 90. Furthermore, the stopper 90 is pressed by the biasing force of the outer spring 51a, transmitted via the control spool 52, such that the first stopper portion 90a abuts the first recessed step surface 86d of the recessed portion 86. Consequently, movement of the control spool 52 to the left in the figure, which is caused by the biasing force of the outer spring 51a, is limited by the stopper 90.

[0050] The assist spring 70 is a coil spring. One end of the assist spring 70 is seated on a seating member 75 housed in a recess 86 of a cover 85, while the other end is seated on the flange 54 of the control spool 52. The assist spring 70 passes through a central hole 90c in a stopper 90 and is compressed between the seating member 75 and the flange 54 of the control spool 52.

[0051] The seating member 75 includes a plate-shaped base portion 76 that slides against the inner circumferential surface of the first recess 86a of the recess 86 of the cover 85; a support portion 77 that protrudes axially from the base portion 76 and supports the inner circumference of the assist spring 70; and a shaft portion 78 that protrudes axially from the top end of the support portion 77 and is inserted into the shaft insertion hole 58b of the control spool 52. One end of the assist spring 70 is seated on a stepped surface 76a (the end surface of the base portion 76 on the support portion 77 side) formed by the difference in outer diameter between the base portion 76 and the support portion 77.

[0052] The shaft portion 78 of the seating member 75 is slidably inserted into the shaft insertion hole 58b of the control spool 52, thereby forming a signal pressure chamber 58. The discharge pressure directed into the second control passage 57b is directed as signal pressure into the signal pressure chamber 59 of the control spool 52 and acts on the inner wall of the second control passage 57b that faces the shaft portion 78. The control spool 52 receives the discharge pressure through a pressure-receiving area corresponding to the integral of the cross section of the shaft portion 78 (the shaft insertion hole 58b). This discharge pressure biases the outer spring 51a and the inner spring 51b in a direction that compresses them.

[0053] The adjustment mechanism 80 includes: a female threaded hole 81 formed in the cover 85; a threaded component 82 that is screwed into the female threaded hole 81 and causes the seating component 75 to advance and retreat in the direction of the force applied by the auxiliary spring 70; and a nut 83 that fixes the screwed position of the threaded component 82 relative to the female threaded hole 81.

[0054] The female screw hole 81 is formed to penetrate the bottom of the first recessed portion 86 a of the recessed portion 86 and open to the first recessed portion 86 a.

[0055] The threaded member 82 abuts against the base portion 76 from the axially opposite side to the end face 76a on which the auxiliary spring 70 is seated. The threaded member 82 is adjusted in its threaded engagement position with the female threaded hole 81, thereby advancing and retreating relative to the seating member 75 along its axial direction (the direction of the force acting on the auxiliary spring 70). That is, by advancing and retreating the threaded member 82, the seating member 75 is advanced and retreated in a manner that causes the auxiliary spring 70 to expand and contract, thereby adjusting the set load (initial load) of the auxiliary spring 70. In this way, the force exerted by the auxiliary spring 70 is adjustable. The nut 83 is screwed onto the threaded member 82 and tightened relative to the cover 85, thereby fixing the threaded position of the threaded member 82 relative to the female threaded hole 81.

[0056] As described above, the control spool 52 is biased away from the swash plate 8 (leftward in the figure) by the forces exerted by the outer spring 51a and the inner spring 51b. Furthermore, the control spool 52 is biased toward the swash plate 8 by the discharge pressure of the piston pump 100, which is directed into the signal pressure chamber 59, and the force exerted by the assist spring 70. In other words, the control spool 52 moves in a manner balanced by the forces exerted by the outer and inner springs 51a, 51b, the assist spring 70, and the discharge pressure of the piston pump 100.

[0057] Specifically, the control spool valve 52 moves between two positions: a first position and a second position. Figure 1 as well as Figure 2 (described later Figure 3 、 Figure 4 The control spool valve 52 is in the second position. Figure 1 as well as Figure 2 The second position shown is switched to the first position by moving to the right in the figure.

[0058] The first position reduces the tilt angle of the swash plate 8, thereby reducing the discharge capacity of the piston pump 100. In the first position, the discharge pressure passage 10 and the control pressure passage 11 of the housing body 3a are connected via the second control port 56b of the control spool 52, while the first control passage 57a of the control spool 52 and the control pressure passage 11 are disconnected. Consequently, in the first position, the discharge pressure of the piston pump 100 is directed to the control pressure chamber 33 of the first biasing mechanism 30.

[0059] The second position increases the tilt angle of the swash plate 8, thereby increasing the discharge capacity of the piston pump 100. In the second position, the control pressure passage 11 communicates with the first control passage 57a of the control spool 52 via the first control port 56a, while the discharge pressure passage 10 and the control pressure passage 11 are disconnected. Consequently, in the second position, the tank pressure is introduced into the control pressure chamber 33.

[0060] Next, the operation of the piston pump 100 will be described.

[0061] The piston pump 100 performs horsepower control in which the discharge capacity (tilt angle of the swash plate 8 ) of the piston pump 100 is controlled by the regulator 50 so as to maintain the discharge pressure of the piston pump 100 constant.

[0062] The control spool valve 52 of the regulator 50 is urged to the first position by the force exerted by the discharge pressure of the piston pump 100 and the force exerted by the auxiliary spring 70, and is urged to the second position by the force of the outer spring 51a and the inner spring 51b.

[0063] When the force exerted by the discharge pressure of the piston pump 100 and the force exerted by the auxiliary spring 70 are kept below the force of the outer spring 51a, the control spool 52 of the regulator 50 is located in the second position, and the tilt angle of the swash plate 8 is maintained at the maximum (see Figure 1 ).

[0064] The discharge pressure of the piston pump 100 increases as the load on the hydraulic cylinder driven by the piston pump 100's discharge pressure increases. From the state where the tilt angle of the swash plate 8 is maintained at its maximum, when the discharge pressure of the piston pump 100 increases, the combined force of the discharge pressure and the force of the assist spring 70 becomes greater than the force of the outer spring 51a. This causes the control spool 52 to move from the second position to the first position (rightward in the figure). When the control spool 52 moves to the first position, discharge pressure is directed from the discharge pressure passage 10 to the control pressure passage 11, thereby increasing the control pressure. More specifically, as the control spool 52 moves to the first position, the opening area (flow path area) of the second control port 56b of the control spool 52 relative to the control pressure passage 11 increases. Consequently, as the control spool 52 moves toward the first position (rightward in the figure), the control pressure directed to the control pressure passage 11 increases. Since the control pressure introduced into the control pressure passage 11 increases, the large-diameter piston 32 (see Figure 1 ) moves toward the swash plate 8, and the swash plate 8 tilts in a direction in which the tilt angle becomes smaller. As a result, the discharge capacity of the piston pump 100 decreases.

[0065] When the swash plate 8 tilts toward a smaller tilt angle, the small-diameter piston 42 compresses the outer spring 51a and inner spring 51b, moving leftward in the figure, following the swash plate 8. In other words, when the swash plate 8 tilts toward a smaller tilt angle, the small-diameter piston 42 moves toward the second position, biasing the control spool 52 via the outer spring 51a (and inner spring 51b). As the control spool 52 is pushed back and moves toward the second position, the control pressure supplied to the control pressure chamber 33 via the control pressure passage 11 decreases. As the control pressure decreases, the force applied to the swash plate 8 by the control pressure balances the force applied to the swash plate 8 by the outer spring 51a (and inner spring 51b), and the movement of the large-diameter piston 32 (tilting of the swash plate 8) stops. Thus, as the discharge pressure of the piston pump 100 increases, the discharge capacity decreases.

[0066] Conversely, the discharge pressure of the piston pump 100 decreases as the load on the hydraulic cylinder driven by the discharge pressure of the piston pump 100 decreases. When the discharge pressure of the piston pump 100 decreases, the combined force of the force exerted by the discharge pressure of the piston pump 100 and the force exerted by the auxiliary spring 70 becomes less than the force exerted by the outer spring 51a and the inner spring 51b. This causes the control spool valve 52 to move from the first position to the second position. When the control spool valve 52 moves to the second position, the control pressure passage 11 connects to the first control passage 57a, which is at tank pressure, thereby reducing the control pressure. As the control pressure decreases, the swash plate 8 tilts in a direction that increases the tilt angle due to the small-diameter piston 42 acting upon the outer spring 51a and the inner spring 51b.

[0067] When the swash plate 8 tilts in a direction that increases its tilt angle, the small-diameter piston 42, acting under the urging force of the outer and inner springs 51a and 51b, follows the swash plate 8 and moves rightward in the figure, extending the outer and inner springs 51a and 51b. This reduces the urging force on the control spool 52 from the outer and inner springs 51a and 51b. Consequently, the control spool 52 receives the discharge pressure directed to the second control passage 57b and moves in a direction that compresses the outer and inner springs 51a and 51b. In other words, the control spool 52 moves from the second position to the first position, following the small-diameter piston 42. When the control spool 52 returns to the first position, the control pressure increases. When the force exerted on the swash plate 8 by the control pressure balances the force exerted on the swash plate 8 by the outer and inner springs 51a and 51b, the movement of the large-diameter piston 32 (tilting of the swash plate 8) stops. In this way, when the discharge pressure of the piston pump 100 decreases, the discharge capacity increases.

[0068] As described above, horsepower control is performed such that the discharge capacity of the piston pump 100 is reduced by increasing the discharge pressure of the piston pump 100 and the discharge capacity is increased by decreasing the discharge pressure.

[0069] Here, in order to easily understand the present invention, reference is made to Figure 4 , a regulator 250 according to a comparative example of the present invention will be described. The same components as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment, and description thereof will be omitted.

[0070] The adjuster 250 according to the comparative example includes a sleeve 260 mounted in the mounting hole 3e formed in the housing body 3a. In the comparative example, the assist spring 70 and the adjustment mechanism 80 of the present embodiment are not provided.

[0071] The sleeve 260 is mounted to the housing body 3a by threading into the female thread 203 formed in the mounting hole 3e of the housing body 3a. The sleeve 260 has a spool-receiving hole 250a formed in it, into which the control spool 52 is inserted. Furthermore, the sleeve 260 has a first communicating hole 261a and a second communicating hole 261b. The first communicating hole 261a communicates with the control pressure passage 11 via a first port 260a formed on its outer circumference, while the second communicating hole 261b communicates with the discharge pressure passage 10 via a second port 260b formed on its outer circumference. The first port 260a and the second port 260b are each annular grooves formed on the outer circumference of the sleeve 260. The first communicating hole 261a and the second communicating hole 261b intersect with the spool-receiving hole 250a and communicate with the spool-receiving hole 250a.

[0072] As in the above-described embodiment, one end of the spool accommodating hole 250a formed in the sleeve 260 opens into the second piston accommodating hole 41 that accommodates the small-diameter piston 42. The other end of the spool accommodating hole 250a is sealed by a plug 270 threadably mounted on the sleeve 260. The plug 270 also includes a shaft 278 that is inserted into the shaft insertion hole 58b formed in the control spool 52. The shaft 278 of the plug 270 corresponds to the shaft 78 in the above-described embodiment.

[0073] In the comparative example, in the first position, the first communication hole 261a and the second communication hole 261b of the sleeve 260 communicate via the second control port 56b of the control spool 52, and communication between the first control passage 57a of the control spool 52 and the first communication hole 261a is cut off. Thus, in the first position, the discharge pressure of the piston pump 100 is directed to the control pressure chamber 33 of the first biasing mechanism 30.

[0074] In the second position, the first communication hole 261a communicates with the first control passage 57a of the control spool 52 via the first control port 56a, while the second communication hole 261a and the second communication hole 261b are disconnected. Thus, in the second position, the tank pressure is introduced into the control pressure chamber 33.

[0075] Here, due to machining errors (dimensional errors) in the control spool and outer spring, these errors may also cause errors in the set load of the outer spring. Errors in the set load of the outer spring may also cause errors in the control characteristics of the swash plate's tilt angle relative to changes in the piston pump load (in other words, the horsepower control characteristics) implemented by the regulator.

[0076] In the regulator 250 according to the comparative example, by adjusting the threaded position of the sleeve 260 relative to the housing body 3a and advancing and retracting the sleeve 260 and the control spool 52 housed therein relative to the outer spring 51a, the outer spring 51a can be expanded and contracted, thereby adjusting the set load of the outer spring 51a. This means that, in the comparative example, it is possible to adjust for errors in the control characteristics of the regulator 250 caused by machining errors in the control spool 52, thereby achieving desired control characteristics.

[0077] However, in the comparative example, the first port 260a formed in the sleeve 260 and the control pressure passage 11 formed in the housing body 3a, as well as the second port 260b formed in the sleeve 260 and the discharge pressure passage 10 formed in the housing body 3a, must always be in communication. Therefore, in a structure where the sleeve 260 is moved to adjust the control characteristics as in the comparative example, the sleeve 260 can only be moved within the range where the sleeve 260 hole and the passage in the housing body 3a communicate, limiting the degree of control characteristic adjustment. Specifically, in the comparative example, the degree of control characteristic adjustment (adjustment range) is limited due to the constraints imposed by the relative positional relationship between the sleeve 260, the control spool 52, and the housing body 3a.

[0078] In contrast, in this embodiment, as described above, the control spool valve 52 moves in a manner that balances the force exerted by the discharge pressure (self-pressure) of the piston pump 100, the forces exerted by the outer and inner springs 51a and 51b, and the force exerted by the auxiliary spring 70, thereby regulating the control pressure. This allows the piston pump 100 to be horsepower-controlled. Specifically, the characteristics of the horsepower control implemented by the regulator 50 are influenced by the forces exerted by the outer and inner springs 51a and 51b, and the force exerted by the auxiliary spring 70.

[0079] In this embodiment, the control characteristics are adjusted not by expanding or contracting the outer spring 51a (in other words, by adjusting the set load of the outer spring 51a), but rather by adjusting the force (set load) applied to the assist spring 70 by the adjustment mechanism 80. By adjusting the force applied to the assist spring 70 by the adjustment mechanism 80, the control characteristics can be adjusted without changing the relative positional relationship between the control spool 52 and the housing body 3a—in other words, without expanding or contracting the outer spring 51a. This allows the control characteristics to be adjusted without being affected by the relative positional relationship between the control spool 52 and the housing body 3a, thereby achieving the desired control characteristics with greater precision.

[0080] Furthermore, the purpose is not limited to adjusting the error in the control characteristic due to the machining error of the control spool 52 , and the control characteristic can also be adjusted according to the application for which the piston pump 100 is used.

[0081] The force exerted by the assist spring 70 is determined based on the specifications of the piston pump 100, the purpose of the piston pump 100 (in other words, the specifications of the actuator that supplies the hydraulic oil), the specifications of the power source (e.g., the engine), etc. Furthermore, it is preferable that the force (set load) of the assist spring 70 be adjusted by the adjustment mechanism 80 within a range that does not exceed the combined force exerted by the outer spring 51a and the inner spring 51b regardless of the tilt angle of the swash plate 8. In other words, it is preferable that the maximum set load exerted by the assist spring 70 be configured to correspond to the maximum load when the tilt angle of the swash plate 8 is at its maximum ( Figure 1 (see the state shown), the force exerted by the outer spring 51a is relatively small. Consequently, the forces exerted by the outer spring 51a and the inner spring 51b are dominant factors in determining the control characteristics. Furthermore, the control spool 52 can be prevented from moving in a manner that compresses the outer spring 51a due to the adjustment (increase) of the force of the assist spring 70. This prevents the communication between the passage formed in the housing body 3a and the port formed in the control spool 52 from being accidentally altered due to the adjustment of the force of the assist spring 70.

[0082] In addition, Figure 4In the comparative example shown, the sleeve 260 is inserted into the mounting hole 3e of the housing body 3a, and the control spool 52 is inserted into the spool receiving hole 250a of the sleeve 260. Therefore, in the comparative example, hydraulic oil leakage may occur at two locations: between the housing body 3a and the sleeve 260, and between the sleeve 260 and the control spool 52. In contrast, in this embodiment, the sleeve 260 as in the comparative example is not provided, and the control spool 52 is directly inserted into the spool receiving hole 50a formed in the housing body 3a. This reduces the number of locations where hydraulic oil leakage may occur compared to the comparative example, thereby suppressing hydraulic oil leakage. Furthermore, the lack of the sleeve 260 in this embodiment reduces the number of parts compared to the comparative example, thereby reducing costs and enabling a more compact piston pump 100.

[0083] In addition, the piston pump 100 only needs to have a structure in which the force of the auxiliary spring 70 is adjusted at least by the adjustment mechanism 80, and the structure in which the control slide valve 52 is directly inserted into the slide valve receiving hole 50a formed in the housing body 3a is not essential. Figure 4 The sleeve 260 of the comparative example shown. In other words, Figure 4 In the comparative example shown, an embodiment in which the adjustment mechanism 80 of the present embodiment is provided and the biasing force of the assist spring 70 is adjusted by the adjustment mechanism 80 falls within the scope of the present invention.

[0084] According to the above embodiment, the following effects are achieved.

[0085] In the piston pump 100, the control characteristics of the regulator 50 are adjusted by adjusting the biasing force of the assist spring 70 using the adjustment mechanism 80. Thus, even if errors in the control characteristics occur due to, for example, machining errors in the control spool 52, the desired control characteristics can be achieved with high precision by adjusting the biasing force of the assist spring 70.

[0086] Furthermore, in the piston pump 100, the biasing force of the assist spring 70 is adjusted by the adjustment mechanism 80. Therefore, the control characteristics of the regulator 50 can be adjusted without adjusting the set loads of the outer spring 51a and the inner spring 51b. Therefore, the control characteristics can be adjusted without being affected by the relative positional relationship between the control spool 52 and the housing body 3a, thereby achieving the desired control characteristics with greater precision.

[0087] Furthermore, in the piston pump 100, the biasing force (set load) of the assist spring 70 is adjusted within a range that does not exceed the combined force of the outer and inner springs 51a, 51b. Consequently, even when the biasing force of the assist spring 70 is increased, movement of the control spool 52, which would compress the outer and inner springs 51a, 51b, is prevented. This prevents unintended movement of the control spool 52 when adjusting the biasing force of the assist spring 70. Consequently, unintended changes in the communication between the ports (first and second control ports 56a, 56b) formed in the control spool 52 and the passages (discharge pressure passage 10 and control pressure passage 11) formed in the housing body 3a can be prevented.

[0088] Furthermore, in the piston pump 100 , the control spool 52 is directly inserted into the spool accommodating hole 50 a of the housing body 3 a , thereby suppressing leakage of hydraulic oil and reducing the number of parts, thereby achieving miniaturization and cost reduction of the piston pump 100 .

[0089] (Second embodiment)

[0090] The second embodiment of the present invention will be described below with reference to the accompanying drawings. The following description will focus on differences from the first embodiment. Components identical to those in the first embodiment will be designated with the same reference numerals, and their description will be omitted. Specifically, the second embodiment differs only in the structure of the regulator 150 from the regulator 50 of the first embodiment; all other components are identical.

[0091] In the first embodiment, the auxiliary spring 70 passes through the central hole 90c of the stopper 90 and is provided between the seat member 75 and the control spool 52. The shaft 78 of the seat member 75 is inserted into the shaft insertion hole 58b of the control spool 52.

[0092] In contrast, in the regulator 150 of the second embodiment, as shown in FIG. Figure 3 As shown, the auxiliary spring 70 is provided in a compressed state between the stopper 190 and the seating member 175. This will be described in detail below.

[0093] In the second embodiment, the control spool 152 does not have the flange portion 54 and is not provided with the shaft insertion hole 58 b . The end portion of the control spool 152 on the stopper 190 side abuts against the end surface of the stopper 190 .

[0094] One end of the assist spring 70 is seated on the end surface of the stopper 190 opposite to the control spool 152. Two shaft insertion holes 191a and 191b are formed along the axial direction of the stopper 190. The stopper 190 in this embodiment corresponds to a "partitioning member."

[0095] The seating member 175 includes a pair of shafts 78a and 78b that protrude axially from the support portion 77. The shafts 78a and 78b are inserted into a pair of shaft insertion holes 191a and 191b formed in the stopper 190. Consequently, the shafts 78a and 78b and the inner walls of the shaft insertion holes 191a and 191b into which they are inserted form a pair of signal pressure chambers 193a and 193b for guiding the signal pressure used for horsepower control.

[0096] The signal pressure chamber 193a on one side communicates with the discharge pressure passage 10 via a first communication port 190a formed on the outer periphery of the stopper 190, a first connection passage 192a connecting the signal pressure chamber 193a and the first communication port 190a, and a first cover passage 85a formed in the cover 85. The signal pressure chamber 193b on the other side communicates with an external pressure passage (not shown) formed in the housing body 3a via a second communication port 190b formed on the outer periphery of the stopper 190, a second connection passage 192b connecting the signal pressure chamber 193b and the second communication port 190b, and a second cover passage 85b formed in the cover 85. For example, external pump pressure as a signal pressure discharged from another hydraulic pump driven by the power source together with the piston pump 100 is guided to the external pressure passage.

[0097] Thus, although in this embodiment, the discharge pressure of the piston pump 100 and the discharge pressure of other hydraulic pumps are guided to the signal pressure chambers 193a and 193b as signal pressure, the present invention is not limited to this structure. For example, three or more signal pressure chambers may be formed on the limit member 190, or one signal pressure chamber may be formed. In addition, the type of signal pressure is not limited to the above-mentioned embodiment, and can be arbitrarily configured according to the purpose of the piston pump 100, etc. For example, in the case where the piston pump 100 is a so-called diverter type that discharges working oil from two ports, the discharge pressure of the working oil discharged from one port may be guided to the signal pressure chamber on one side as signal pressure, and the discharge pressure of the working oil discharged from the other port may be guided to the signal pressure chamber on the other side as signal pressure.

[0098] The signal pressure directed to the signal pressure chambers 193a and 193b acts on the inner wall portions of the signal pressure chambers 193a and 193b that are opposite the shaft portions 78a and 78b. As a result, the control spool 152 receives the signal pressure via the stopper 190 across a pressure-receiving area corresponding to the cross-sectional area of ​​the shaft portions 78a and 78b (in other words, the cross-sectional area of ​​the shaft portion insertion holes 191a and 191b). The signal pressure then compresses the outer spring 51a and the inner spring 51b.

[0099] Thus, in the piston pump 100 according to this embodiment, the control spool valve 52 of the regulator 150 is biased toward the first position by the force exerted by the discharge pressure (signal pressure) of the piston pump 100 applied via the stopper 190, the discharge pressure (signal pressure) of another hydraulic pump applied via the stopper 190, and the biasing force exerted by the assist spring 70. Furthermore, the control spool valve 52 is biased toward the second position by the biasing forces of the outer spring 51a and the inner spring 51b.

[0100] The horsepower control performed by the regulator 150 in the second embodiment differs from the first embodiment only in the number and type of signal pressures for urging the control spool 52 to the first position. Other points are the same as those in the first embodiment, so detailed description is omitted.

[0101] According to the second embodiment described above, the following effects are achieved.

[0102] In the second embodiment, a pair of shafts 78a and 78b are inserted into a stopper 190. Signal pressure chambers 193a and 193b are formed within the stopper by the shafts 78a and 78b. By forming the signal pressure chambers 193a and 193b on the stopper 190 rather than on the control spool 52, the size of the control spool 52 can be reduced. Furthermore, since the signal pressure chambers 193a and 193b are formed on the stopper 190, it is easier to form multiple signal pressure chambers 193a and 193b than if the signal pressure chambers 193a and 193b were formed on the control spool 52. This makes it easier to increase the number of control factors for horsepower control, enabling more precise horsepower control.

[0103] Hereinafter, the configuration, function, and effects of the embodiments of the present invention will be summarized and described.

[0104] The piston pump 100 comprises: a cylinder block 2, which rotates as the shaft 1 rotates; a plurality of cylinders 2b, which are formed in the cylinder block 2 and arranged in a circumferential direction of the shaft 1 at predetermined intervals; a piston 5, which is inserted into the cylinder 2b in a freely slidable manner and defines a volume chamber 6 inside the cylinder 2b; a swash plate 8, which is tiltable and reciprocates the piston 5 in a manner that expands and contracts the volume chamber 6 as the cylinder block 2 rotates; a first force applying mechanism 30, which applies force to the swash plate 8 in accordance with a supplied control pressure; a second force applying mechanism 40, which applies force to the swash plate 8 in a manner that resists the first force applying mechanism 30; and a regulating mechanism. The regulators 50 and 150 control the control pressure directed to the first force mechanism 30 according to the self-pressure of the piston pump 100. The regulators 50 and 150 include: an outer spring 51a and an outer spring 51b, which expand and contract following the inclination of the inclined plate 8; a control slide valve 52, which moves according to the force of the outer spring 51a and the inner spring 51b, thereby adjusting the control pressure; an auxiliary spring 70, which exerts a force relative to the control slide valve 52 in a manner that resists the force of the outer spring 51a and the inner spring 51b; and an adjusting mechanism 80, which adjusts the force exerted by the auxiliary spring 70.

[0105] In this configuration, the control spool 52 of the regulator 50 or 150 moves based on the forces of the outer and inner springs 51a and 51b, as well as the force of the assist spring 70, thereby adjusting the control pressure. Thus, by adjusting the force of the assist spring 70 using the adjustment mechanism 80, the control characteristics of the regulator 50 or 150 can be adjusted to achieve the desired control characteristics. This improves the accuracy of horsepower control of the piston pump 100.

[0106] Furthermore, in the piston pump 100 , the adjustment mechanism 80 is configured to be able to adjust the biasing force of the assist spring 70 within a range that does not exceed the biasing force exerted by the outer spring 51 a and the inner spring 51 b .

[0107] In this structure, it is possible to prevent unintended movement of the control spool 52 when adjusting the biasing force of the assist spring 70 .

[0108] The piston pump 100 further includes a housing 3 that houses the cylinder block 2 . The housing 3 has a spool housing hole 50 a formed therein, into which a control spool 52 is slidably inserted.

[0109] In this structure, the control slide valve 52 is inserted into the slide valve receiving hole 50a of the housing 3 in a freely sliding manner. Figure 4As in the comparative example shown, when a sleeve 260 is housed in a mounting hole 3e formed in the housing 3 and a control spool 52 is slidably inserted into the sleeve 260, leakage of the working fluid occurs between the housing 3 and the sleeve 260, and between the sleeve 260 and the control spool 52. In contrast, in the present invention, the control spool 52 is directly inserted into the housing body 3a, thereby suppressing leakage of the working fluid.

[0110] In addition, in the second embodiment, the regulator 150 further includes: a limit member 190, which is arranged between the control slide valve 52 and the auxiliary spring 70; and signal pressure chambers 193a, 193b, which are divided by the limit member 190 and guide the signal pressure, and the signal pressure applies force to the control slide valve 52 in a manner that resists the force of the outer spring 51a and the inner spring 51b.

[0111] In this configuration, the control characteristics of the regulator 150 can be modified by directing the signal pressure to the signal pressure chambers 193a and 193b. Thus, by directing the signal pressure corresponding to the device in which the piston pump 100 is applied to the signal pressure chambers 193a and 193b, appropriate control characteristics corresponding to the intended application can be achieved. Furthermore, since the signal pressure chambers 193a and 193b are divided by the stopper 190, a separate component from the control spool 52 that controls the control pressure, manufacturing is easier than if the signal pressure chambers 193a and 193b were formed within the control spool 52.

[0112] While the embodiments of the present invention have been described above, the above embodiments merely represent a part of application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Claims

1. A hydraulic rotary machine, wherein: have: a cylinder block, which rotates with the drive shaft; a plurality of cylinders formed in the cylinder block and arranged at predetermined intervals in a circumferential direction of the drive shaft; a piston inserted into the cylinder in a freely slidable manner and defining a volume chamber inside the cylinder; a slant plate capable of tilting and causing the piston to reciprocate in a manner that causes the volume chamber to expand and contract; a first urging mechanism for urging the swash plate according to a supplied control pressure; a second force applying mechanism for applying force to the swash plate in a manner resisting the first force applying mechanism; a regulator that controls the control pressure directed to the first urging mechanism according to the self-pressure of the hydraulic rotary machine, The regulator has: a force applying member that expands and contracts following the tilt of the inclined plate; a control spool valve that moves according to the force of the force-applying member, thereby adjusting the control pressure; an auxiliary force-applying member configured to exert a force on the control spool valve in a manner resisting the force of the force-applying member; An adjusting mechanism adjusts the force exerted by the auxiliary force-applying component.

2. The hydraulic rotary machine according to claim 1, wherein: The adjustment mechanism is configured to be able to adjust the biasing force of the auxiliary biasing member within a range that does not exceed the biasing force exerted by the biasing member.

3. The hydraulic rotary machine according to claim 1 or 2, wherein: It also includes a housing for housing the cylinder block. The housing is provided with a slide valve receiving hole into which the control slide valve is inserted in a freely slidable manner.

4. The hydraulic rotary machine according to claim 1 or 2, wherein: The regulator also has: a partition member disposed between the control slide valve and the auxiliary force applying member; A signal pressure chamber is partitioned by the partition member and guides a signal pressure for urging the control spool valve against the urging force of the urging member.

Images