CN118234946A - Hydraulic rotary machine - Google Patents

Abstract

A piston pump (100) is provided with: a first urging section (20) that urges the swash plate (8) according to the supplied control pressure; a second urging portion (30) that urges the swash plate (8) so as to overcome the first urging portion (20); a regulator (50) for controlling the control pressure guided to the first force application unit (20) according to the self-pressure of the piston pump (100), wherein the regulator (50) comprises: a control spool (52) that moves in response to the biasing force of an outer spring (51 a) and an inner spring (51 b) that expand and contract in response to the tilting of the swash plate (8), thereby adjusting the control pressure; an auxiliary spring (61) that exerts a force on the control spool (52) so as to overcome the force of the outer spring (51 a) and the inner spring (51 b); and a housing chamber (65) for housing the assist spring (61), wherein the signal pressure for exerting thrust force on the control spool (52) is guided to the housing chamber (65).

Description

Hydraulic rotary machine

Technical Field

The present invention relates to a hydraulic rotary machine.

Background

Japanese patent application laid-open No. 2008-240518A discloses a swash plate type piston pump including a horsepower control regulator that controls discharge pressure and discharge flow rate with a rated horsepower characteristic such that an output becomes substantially constant. The swash plate type piston pump includes a small diameter piston driven in a direction in which the tilt angle increases, and a large diameter piston driven in a direction in which the tilt angle decreases, as tilt actuators for changing the tilt angle of the swash plate.

The horsepower control regulator is provided with: a control spring for pressing the feedback pin, which is displaced along with the swash plate, to the swash plate side; and a control spool valve that controls the hydraulic pressure that is guided to the pressure chamber of the large-diameter piston. The hydraulic pressure such as the discharge pressure and the signal pressure acts on the pilot spool, and the pilot spool moves so that the force received by the hydraulic pressure and the force received by the pilot spring are balanced.

Disclosure of Invention

In the horsepower control regulator disclosed in japanese patent application laid-open No. 2008-240518A, the hydraulic pressure led to the pressure chamber of the large-diameter piston is controlled by moving the control spool so that forces received by the spring, the hydraulic pressure, and the like are balanced. Thus, the control characteristic of the horsepower control regulator is determined in accordance with the force acting on the control spool.

In order to realize various control characteristics in such a regulator, it is conceivable to provide a plurality of structures for exerting an output force on the control spool, and to improve the degree of freedom of design. However, when a plurality of structures for urging the pilot spool are provided, the hydraulic rotary machine is increased in size.

The purpose of the present invention is to provide a hydraulic rotary machine that can improve the degree of freedom of control characteristics implemented by a regulator while suppressing an increase in size.

According to one aspect of the present invention, a hydraulic rotary machine includes: a cylinder block that rotates together with the drive shaft; a plurality of cylinders formed at the cylinder block and configured to have a predetermined interval in a circumferential direction of the drive shaft; a piston slidably inserted into the cylinder and defining a volume chamber in the cylinder; a swash plate capable of tilting and reciprocating the piston to expand and contract the volume chamber; a first urging portion that urges the swash plate according to a supplied control pressure; a second urging portion that urges the swash plate so as to overcome the first urging portion; a regulator that controls a control pressure that is guided to the first urging portion, the regulator including: a biasing member that expands and contracts in accordance with tilting of the swash plate; a control spool that moves in accordance with the biasing force of the biasing member to adjust the control pressure; an auxiliary biasing member that exerts a biasing force on the control spool so as to overcome the biasing force of the biasing member; a housing chamber for housing the auxiliary biasing member, the housing chamber being configured to guide a signal pressure for generating a thrust force to the control spool so as to overcome the biasing force of the biasing member

Drawings

Fig. 1 is a cross-sectional view of a hydraulic rotary machine according to a first embodiment of the present invention.

Fig. 2 is a diagram showing a structure of a regulator of a hydraulic rotary machine according to a first embodiment of the present invention, and is an enlarged cross-sectional view of a portion a in fig. 1.

Fig. 3 is a view showing a state in which the pilot spool is moved from the state of fig. 2 and is brought into contact with the housing body.

Fig. 4 is a cross-sectional view showing a modification of the hydraulic rotary machine according to the first embodiment of the present invention, and is a view corresponding to fig. 2.

Fig. 5 is a cross-sectional view showing a structure of a regulator of a hydraulic rotary machine according to a second embodiment of the present invention.

Fig. 6 is a diagram showing a structure of a regulator of a hydraulic rotary machine according to a second embodiment of the present invention, and is an enlarged cross-sectional view of a portion B in fig. 2.

Fig. 7 is a diagram for explaining the action of the transfer pin in the second embodiment of the present invention, and is an enlarged view of the contact portion of the transfer pin and the second seating portion.

Fig. 8 is an enlarged cross-sectional view showing a structure of a regulator of a hydraulic rotary machine according to a third embodiment of the present invention.

Fig. 9 is a cross-sectional view of a hydraulic rotary machine according to a fourth embodiment of the present invention.

Detailed Description

(First embodiment)

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

The hydraulic rotary machine 100 functions as a piston pump that can supply working oil as a working fluid by rotating a shaft (drive shaft) 1 by power from an external drive source to reciprocate a piston 5. The hydraulic rotary machine 100 also functions as a piston motor that can output a rotational driving force by reciprocating the piston 5 by the fluid pressure of the hydraulic oil supplied from the outside to rotate the shaft 1. The hydraulic rotary machine 100 may function as a piston pump alone or as a piston motor alone. The driving source for driving the hydraulic rotary machine 100 is, for example, an engine or an electric motor.

In the following description, a case in which the hydraulic rotary machine 100 is used as a piston pump is exemplified, and the hydraulic rotary machine 100 is referred to as "piston pump 100".

The piston pump 100 is used as a hydraulic pressure supply source for supplying hydraulic oil to an actuator (not shown) such as a hydraulic cylinder that drives a driving object. As shown in fig. 1, the piston pump 100 includes: a shaft 1 rotated by a driving source; a cylinder 2 coupled to the shaft 1 and rotated together with the shaft 1; a housing 3 for housing the cylinder 2.

The housing 3 includes: a bottomed tubular case body 3a; a cover 3b that seals an opening end of the housing body 3a and allows the shaft 1 to be inserted therethrough; an auxiliary housing portion 3f for housing an auxiliary urging portion 60 described later. The interior of the housing 3 communicates with a fluid tank (not shown) via a drain passage (not shown). The interior of the housing 3 may communicate with a suction passage (not shown) described below.

A power source (not shown) such as an engine is connected to one end 1a of the shaft 1 protruding outward through the insertion hole 3c of the cover 3 b. The end 1a of the shaft 1 is rotatably supported by the insertion hole 3c of the cover 3b via a bearing 4 a. The other end 1b of the shaft 1 is received in a shaft receiving hole 3d provided in the bottom of the housing body 3a, and is rotatably supported by a bearing 4 b. Although not shown, a rotary shaft (not shown) of another hydraulic pump (not shown), such as a gear pump driven by a power source together with the piston pump 100, is coaxially coupled to the other end portion 1b of the shaft 1 so as to rotate together with the shaft 1.

The cylinder 2 has a through hole 2a through which the shaft 1 passes, and is spline-coupled to the shaft 1 via the through hole 2 a. Thereby, the cylinder 2 rotates with the rotation of the shaft 1.

A plurality of cylinders 2b having openings at one end face are formed in parallel with the shaft 1 in the cylinder block 2. The plurality of cylinders 2b are formed with a predetermined interval in the circumferential direction of the cylinder block 2. A cylindrical piston 5 that divides the volume chamber 6 is inserted into the cylinder 2b so as to reciprocate. The tip side of the piston 5 protrudes from the opening of the cylinder 2b, and a spherical seat 5a is formed at the tip of the piston 5.

The piston pump 100 further has: a shoe 7 rotatably coupled to the spherical seat 5a of the piston 5 and in sliding contact with the spherical seat 5 a; a swash plate 8 that slides on the shoe 7 in association with the rotation of the cylinder block 2; a valve plate 9 provided between the cylinder block 2 and the bottom surface of the housing body 3 a.

The shoe 7 includes: a housing portion 7a for housing a spherical seat 5a formed at the tip end of each piston 5; a circular flat plate portion 7b in sliding contact with the sliding contact surface 8a of the swash plate 8. The inner surface of the housing portion 7a is formed in a spherical shape and is in sliding contact with the outer surface of the housed spherical seat 5 a. Thereby, the shoe 7 can be angularly displaced in all directions with respect to the spherical seat 5 a.

The swash plate 8 is supported to be tiltable by the cover 3b so as to vary the discharge amount of the piston pump 100. The flat plate portion 7b of the shoe 7 makes surface contact with the sliding contact surface 8 a.

The valve plate 9 is a disk 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 3 a. Although not shown, the valve plate 9 is provided with an intake port connecting the intake passage formed in the cylinder block 2 with the volume chamber 6 and a discharge port connecting the discharge passage formed in the cylinder block 2 with the volume chamber 6.

The piston pump 100 further includes: a first biasing unit 20 that tilts the swash plate 8 in a direction in which the tilt angle decreases according to the supplied fluid pressure; a second urging portion 30 that urges the swash plate 8 in a direction in which the tilt angle increases so as to overcome the urging force exerted by the first urging portion 20; and a regulator 50 that controls the fluid pressure guided to the first biasing unit 20 according to the inclination angle of the swash plate 8.

As shown in fig. 1, the first urging portion 20 includes: a control piston 22 slidably inserted into a piston accommodation hole 21 formed in the cover 3b and abutting against the swash plate 8; a control pressure chamber 23 that is partitioned by the control piston 22 into the piston housing hole 21.

In the control pressure chamber 23, a fluid pressure (hereinafter referred to as "control pressure") regulated by the regulator 50 is guided. The control piston 22 biases the swash plate 8 in a direction in which the tilt angle decreases by the control pressure led to the control pressure chamber 23.

The second urging portion 30 is a support spring as a support urging member. Hereinafter, the second urging portion 30 will also be referred to as "support spring 30". The support spring 30 is a coil spring, and supports the swash plate 8 by exerting a biasing force against the biasing force of the first biasing portion 20.

As shown in fig. 2, one end of the support spring 30 is seated on the first spring seat 31, and the other end is seated on the bottom of the housing body 3 a. The support spring 30 is provided between the first spring seat 31 and the housing body 3a in a compressed state. The bottom of the case body 3a is seated with the other end portion of the support spring 30, and an annular support groove 3e for supporting the other end portion is formed. Therefore, the support spring 30 is configured to exert no biasing force against the control spool 52 described later.

The first spring seat 21 is a substantially cylindrical member, and has: a cylindrical sliding portion 32; a first boss portion 33 whose outer diameter is smaller than the sliding portion 32 and which protrudes in the axial direction from the sliding portion 32; a second stud portion 34 whose outer diameter is smaller than that of the first stud portion 33 and which protrudes in the axial direction from the first stud portion 33; the third boss portion 35 has a smaller outer diameter than the second boss portion 34, and protrudes in the axial direction from the second boss portion 34.

One end of the support spring 30 is seated on the first spring seat 31 with a stepped surface 32a formed by the difference in outer diameters of the sliding portion 32 and the first boss portion 33 as a seating surface. The first spring seat 31 moves according to the tilting of the swash plate 8 by the biasing forces of the support spring 30 and the outer and inner springs 51a and 51b described later.

The first spring seat 31 is provided with an abutting portion 31a formed in a substantially spherical shape and abutting against the swash plate 8. The sliding portion 32 of the first spring seat 31 is slidably inserted into a guide hole 41, and the guide hole 41 is formed in a guide wall portion 40 provided on the inner periphery of the housing body 3 a. The guide hole 41 is formed in the guide wall 40 so that its center axis is parallel to the center axis of the shaft 1 and parallel to or coaxial with (in the present embodiment, coaxial with) the center axis of a control spool 52 described later.

The sliding portion 32 of the first spring seat 31 slides with respect to the guide hole 41, so that the first spring seat 31 is guided along the central axis direction of the guide hole 41. Thereby, the biasing force of the support spring 30 (and the outer spring 51a and the inner spring 51b described later) is applied to the swash plate 8 along the axial direction of the guide hole 41 via the first spring seat 31. In other words, the first spring seat 31 is moved so as to follow the tilting of the swash plate 8, and the support spring 30 (and the outer spring 51a and the inner spring 51b described later) is expanded and contracted. In this way, the first spring seat 31 also functions as a feedback pin that transmits the tilting of the swash plate 8 to the regulator 50.

The first spring seat 31 may be formed separately so as to be divided into a portion on which the support spring 30, the outer spring 51a, and the inner spring 51b are seated, and a portion that is guided by the guide hole 41 and abuts against the swash plate 8.

As shown in fig. 1, the control piston 22 of the first biasing portion 20 is disposed on the opposite side of the first spring seat 31 so as to sandwich the swash plate 8. That is, the control piston 22 and the first spring seat 31 are arranged so that the positions in the circumferential direction with respect to the central axis of the shaft 1 substantially coincide with each other.

The regulator 50 regulates the control pressure of the control pressure chamber 23 guided to the first urging portion 20 according to the load of the drive source that drives the piston pump 100, and controls the horsepower (output) of the piston pump 100. More specifically, when the load of the drive source varies, the discharge pressure of the piston pump 100 also varies. Thus, in the present embodiment, the regulator 50 regulates the control pressure according to the own pressure of the piston pump 100, thereby performing horsepower control according to the load of the drive source.

The regulator 50 has: an outer spring 51a and an inner spring 51b as biasing members for biasing the swash plate 8 through the first spring seat 31; a control spool 52 that moves in response to the biasing force of the outer spring 51a and the inner spring 51b and adjusts the control pressure; and an auxiliary biasing unit 60 that applies a biasing force to the pilot spool 52 so as to overcome the biasing force applied to the pilot spool 52 by the outer spring 51a and the inner spring 51 b.

The outer springs 51a and the inner springs 51b are coil springs, respectively, and expand and contract so as to follow the tilting of the swash plate 8. The inner spring 51b has a smaller winding diameter than the outer spring 51a, and is provided inside the outer spring 51 a. The outer spring 51a has a smaller winding diameter than the support spring 30, and is provided inside the support spring 30. That is, the outer spring 51a and the inner spring 51b are provided inside the support spring 30.

One end of the outer spring 51a and one end of the inner spring 51b are seated on the first spring seat 31. Specifically, as shown in fig. 2, the outer spring 51a seats on the first spring seat 31 with a stepped surface 33a formed by the difference in outer diameters of the first and second boss portions 33 and 34 of the first spring seat 31 as a seating surface. The inner spring 51b can seat on the first spring seat 31 with the stepped surface 34a generated by the difference in outer diameters between the second boss portion 34 and the third boss portion 35 of the first spring seat 31 as a seating surface. The third boss portion 35 is inserted inside the inside spring 51b, and supports the inner periphery of the inside spring 51 b.

The other ends of the outer spring 51a and the inner spring 51b are seated on the end surface of the control spool 52 via the second spring seat 36. The second spring seat 36 moves with the control spool 52.

The second spring seat 36 is formed to have an outer diameter smaller than an inner diameter of the support spring 30, and the second spring seat 36 is provided inside the support spring 30. As described above, the other end portion of the support spring 20 is not seated on the second spring seat 36, and is seated on the support groove 3e in the bottom portion of the housing body 3 a. As a result, in the support spring 30, one end portion seated on the first spring seat 31 moves so as to follow the tilting of the swash plate 8, and the other end portion seated on the support groove 3e does not move so as to follow the tilting of the swash plate 8. That is, the other end portion of the support spring 30 is configured so as not to generate movement due to tilting of the swash plate 8.

In the state where the tilting angle of the swash plate 8 is maximized (the state shown in fig. 1), the second spring seat 36 is in a state of being floated apart from the bottom of the housing body 3a without being in contact with the bottom of the housing body 3 a.

The natural length (free length) of the outer spring 51a is longer than the natural length of the inner spring 51 b. In the state where the tilting angle of the swash plate 8 is maximized (the state shown in fig. 1), the outer spring 51a is compressed by the first spring seat 31 and the second spring seat 36, while the inner spring 51b is separated from the spring seat (the first spring seat 31 in fig. 1) at one end and floats (as a natural length). That is, when the tilt angle of the swash plate 8 becomes smaller from the maximum state, only the outer spring 51a is compressed initially, and when the length of the outer spring 51a is compressed beyond the natural length of the inner spring 51b, both the outer spring 51a and the inner spring 51b are compressed. With this, the elastic force from the outer spring 51a and the inner spring 51b applied to the swash plate 8 via the first spring seat 31 is gradually increased.

As described above, the support spring 30 and the outer and inner springs 51a and 51b are adjacent to each other and are disposed in parallel with respect to the swash plate 8. More specifically, the outer spring 51a and the inner spring 51b are provided radially inward of the support spring 30. Further, the biasing force of the support spring 30 and the biasing forces of the outer spring 51a and the inner spring 51b are configured to act in parallel with respect to the swash plate 8.

A spool receiving hole 50a into which the control spool 52 is slidably inserted is formed in the housing body 3 a. The spool receiving hole 50a opens at the end face 3g of the housing body 3 a. The opening of the spool receiving hole 50a with respect to the end surface 3g of the housing body 3a is closed by a bottomed tubular auxiliary housing portion 3f attached to the end surface 3g of the housing body 3 a.

Further, the housing body 3a is provided with a discharge pressure passage 10 for guiding the discharge pressure of the piston pump 100 and a control pressure passage 11 for guiding the control pressure to the control pressure chamber 23 of the control piston 22. The discharge pressure of the piston pump 100 is always guided to the discharge pressure passage 10. The control pressure passage 11 communicates with the control pressure chamber 23 via a cover side passage (not shown) formed in the cover 3 b. In fig. 1, a line for guiding the discharge pressure of the piston pump 100 to the discharge pressure passage 10 and a signal pressure passage 12 described later is schematically indicated by a broken line.

As shown in fig. 2, the control spool 52 has: a body portion 53 that is in sliding contact with the inner peripheral surface of the spool receiving hole 50 a; a flange portion 54 provided at one end of the body portion 53 and formed to have a larger outer diameter than the body portion 53; a protruding portion 55 provided at the other end portion of the body portion 53 opposite to the flange portion 54, and inserted into the second spring seat 36.

The flange 54 protrudes from the spool receiving hole 50a to the outside of the housing body 3a, and is received in the auxiliary housing 3f. The outer diameter of the protruding portion 55 is smaller than the main body portion 53, and a stepped surface 55a generated by the difference in outer diameter between the main body portion 53 and the protruding portion 55 abuts against the second spring seat 36.

A first control port 56a and a second control port 56b are formed as annular grooves on the outer periphery of the control spool 52. The control spool 52 is formed with a control passage 57 that communicates with the first control port 56a so as to penetrate the control spool 52 in the radial direction. Further, the control spool 52 is formed with an axial passage 58 provided in the axial direction from one end (the protruding portion 55). The axial passage 58 communicates the control passage 57 with a connecting passage 36a formed in the second spring seat 36 and opening in the interior of the housing body 3 a.

In this way, the control passage 57 communicates with the interior of the housing 3 via the axial passage 58 and the connecting passage 36a of the second spring seat 36. Thereby, the pressure in the control passage 57 becomes the tank pressure.

The auxiliary biasing unit 60 includes: an auxiliary spring 61 as an auxiliary urging member; a first seating portion 70 on which an end portion of the assist spring 61 is seated; a housing chamber 65 formed in the auxiliary case portion 3f and configured to house the auxiliary spring 61; and an adjusting mechanism 80 for adjusting the urging force exerted by the assist spring 61.

The housing chamber 65 is formed by a housing recess 66 formed in the auxiliary case portion 3 f. The housing recess 66 is formed as a bottomed cylindrical recess opening on an end surface (mounting surface) 3h of the auxiliary housing portion 3f mounted on the end surface 3g of the housing body 3 a. That is, the opening of the housing recess 66 is sealed by the end face 3g of the housing body 3 a.

The accommodating recess 66 has: a first recess 66a that opens on the mounting surface 3h of the auxiliary housing portion 3 f; a second recess 66b communicating with the first recess 66a and having a smaller inner diameter than the first recess 66 a; a step surface 66c formed by the difference in inner diameters of the first concave portion 66a and the second concave portion 66 b. The first concave portion 66a and the second concave portion 66b each have a circular cross section formed coaxially with the spool receiving hole 50 a.

The flange portion 54 of the pilot spool 52 is accommodated in the first recess 66 a. The control spool 52 is movable in a direction toward the swash plate 8 (rightward in fig. 2) against the biasing force of the outer spring 51a and the inner spring 51b until the flange 54 abuts against the end surface 3g of the housing body 3 a. That is, the end surface 3g of the housing body 3a functions as a stopper portion, and the flange portion 54 abuts against the end surface 3g of the housing body 3a in accordance with the movement of the pilot spool 52, thereby restricting the movement of the pilot spool 52 further toward the swash plate 8 (see fig. 3).

The pilot spool 52 is biased by the outer spring 51a and the inner spring 51b to be movable in a direction separating from the swash plate 8 (left direction in fig. 2) until the flange 54 comes into contact with the stepped surface 66c of the receiving recess 66 of the auxiliary housing 3 f. In the state where the tilting angle of the swash plate 8 shown in fig. 1 and 2 is maximized, the flange portion 54 of the control spool 52 abuts against the stepped surface 66c of the auxiliary housing portion 3 f. That is, the inner diameter of the first recess 66a of the accommodating recess 66 is formed larger than the inner diameter of the flange portion 54, and the inner diameter of the second recess 66b is formed smaller than the inner diameter of the flange portion 54.

The assist spring 61 is a coil spring, and is provided in a compressed state between the first seat portion 70 and the end surface of the flange portion 54 of the control spool 52. That is, the assist spring 61 applies a force against the direct contact of the control spool 52. The assist spring 61 is provided to exert a biasing force in a direction along the moving direction of the control spool 52.

A communication path 54a whose both ends open to the outer peripheral surface of the flange 54 is formed in the end surface of the flange 54 on which the assist spring 61 is seated. The communication passage 54a is a slit formed so as to extend in the radial direction of the flange 54. Thereby, even in a state where the flange portion 54 is in contact with the step surface 66c, the inner side of the first concave portion 66a and the inner side of the second concave portion 66b are communicated by the communication path 54a. This prevents the housing chamber 65 (housing concave portion 66) from being separated into two chambers by the abutment of the flange portion 54 against the step surface 66 c.

The communication path is not limited to a slit provided in the end surface of the flange 54. For example, a notch may be formed in the stepped surface 66c of the accommodating recess 66. The through hole penetrating the flange portion 54 in the axial direction may be a communication passage, or a passage formed so as to straddle the body portion 53 and the flange portion 54 of the pilot spool 52 may be a communication passage. In this way, the communication path may be provided in at least one of the auxiliary housing portion 3f and the pilot spool 52 so as to communicate the first concave portion 66a and the second concave portion 66b in a state where the flange portion 54 and the stepped surface 66c are located.

The first seating portion 70 is accommodated in the second recess 66b of the accommodating recess 66. The first seating portion 70 has: a circular plate portion 71 provided with a seating surface 71a on which one end of the assist spring 61 is seated; and a protrusion 72 protruding from the seating surface 71a of the disk 71 and supporting the assist spring 61 from the inside. A sealing member (not shown) for sealing a gap between the outer periphery of the circular plate portion 71 and the inner periphery of the second concave portion 66b is provided.

As shown in fig. 2, the adjustment mechanism 80 has: a female screw hole 81 formed in the bottom of the auxiliary housing portion 3 f; a screw member 82 that is screwed into the female screw hole 81 and advances and retreats the first seat 70 in the urging direction of the assist spring 61; and a nut 83 for fixing the screwed position of the screw member 82 with respect to the female screw hole 81.

The female screw hole 81 penetrates the bottom of the auxiliary housing portion 3f and opens into the second recess 66 b. The screw member 82 abuts the first base portion 70 from the side opposite to the side on which the assist spring 61 is seated in the axial direction. The screw member 82 advances and retreats relative to the first seating portion 70 along the axial direction thereof (the direction of the urging force of the assist spring 61) by adjusting the screw position with the female screw hole 81. That is, by advancing and retreating the screw member 82, the first seating member 70 is advanced and retreated so that the assist spring 61 expands and contracts, and the design load (initial load) of the assist spring 61 can be adjusted. Thereby, the urging force exerted by the assist spring 61 can be adjusted. The screw member 82 is screwed into the screw member 82 by the nut 83 and fastened to the auxiliary housing portion 3f, whereby the screwed position of the screw member 82 with respect to the female screw hole 81 is fixed.

The urging force (design load) of the assist spring 61 is adjusted in a range not exceeding the resultant force of the urging forces of the outer spring 51a and the inner spring 51 b. Thereby, unexpected movement of the control spool 52 due to compression of the outer spring 51a and the inner spring 51b when the urging force of the assist spring 61 is adjusted is prevented.

In addition, a signal pressure passage 12 for guiding the signal pressure to the housing chamber 65 is formed in the case body 3 a. The signal pressure passage 12 is formed to open on the end surface 3g of the housing body 3a so as to face the first recess 66a of the housing recess 66. In the present embodiment, the discharge pressure (self pressure) of the piston pump 100 is guided to the housing chamber 65 as the signal pressure corresponding to the load of the drive source. Since the signal pressure is guided to the housing chamber 65, the thrust force generated by the signal pressure acts on the control spool 52. The direction of the thrust force generated by the signal pressure acting on the pilot spool 52 is the same direction as the auxiliary spring 61, that is, the direction in which the pilot spool 52 moves so as to compress the outer spring 51a and the inner spring 51 b. In this way, the housing chamber 65 functions as a signal pressure chamber that houses the assist spring 61 and is guided by the signal pressure to exert thrust on the control spool 52.

The signal pressure passage 12 is preferably configured so as not to be closed by the flange 54 that abuts against the end surface 3g of the housing body 3 a. Specifically, for example, the signal pressure passage 12 may be formed to open at the end surface 3g of the case body 3a at a position radially outside the flange 54. Further, a groove extending in the radial direction or a passage penetrating the flange portion 54 in the axial direction may be formed in the flange surface of the flange portion 54 that abuts against the end surface 3g of the housing body 3a, and the signal pressure passage 12 and the first concave portion 66a may be communicated with each other through the groove or the passage.

In addition, even in a state where the flange portion 54 is in contact with the stepped surface 66c of the housing recess 66, the first recess 66a and the second recess 66b are not blocked, and therefore the signal pressure passage 12 may be formed in the auxiliary case portion 3f so as to open in the first recess 66a or the second recess 66 b. In this way, in the present embodiment, the degree of freedom in designing the position where the signal pressure passage 12 is formed is improved. In addition, as in the present embodiment, the signal pressure passage 12 is formed to open on the end face of the housing body 3a, and the signal pressure passage 12 is not formed on the auxiliary housing portion 3f, so that it is not necessary to secure a space for forming the signal pressure passage 12 on the auxiliary housing portion 3f. Therefore, the auxiliary housing portion 3f can be miniaturized.

As described above, the pilot spool 52 is biased in the direction of separation from the swash plate 8 (left direction in the drawing) by the biasing force of the outer spring 51a and the inner spring 51 b. The pilot spool 52 is biased in the direction approaching the swash plate 8 by the biasing force of the assist spring 61 and the thrust force of the discharge pressure (signal pressure) of the piston pump 100 guided to the housing chamber 65. That is, the control spool 52 moves so that the forces exerted by the discharge pressures of the outer and inner springs 51a and 51b, the assist spring 61, and the piston pump 100 are balanced.

Specifically, the control spool 52 moves between the first position and the second position. Fig. 1 and 2 show the state in which the pilot spool 52 is in the second position. The control spool 52 is switched to the first position shown in fig. 3 in association with the movement in the right direction in the drawing from the second position shown in fig. 1 and 2.

The first position is a position at which the discharge capacity of the piston pump 100 is reduced by reducing the tilting angle of the swash plate 8. In the first position, the discharge pressure passage 10 and the control pressure passage 11 of the housing body 3a communicate via the second control port 56b of the control spool 52, and the communication between the control passage 57 and the control pressure passage 11 of the control spool 52 is cut off. Thereby, in the first position, the discharge pressure of the piston pump 100 is guided to the control pressure chamber 23 of the first urging portion 20.

The second position is a position at which the discharge capacity of the piston pump 100 increases by increasing the tilting angle of the swash plate 8. In the second position, the control pressure passage 11 and the control passage 57 of the control spool 52 communicate via the first control port 56a, and the communication between the discharge pressure passage 10 and the control pressure passage 11 is cut off. Thereby, in the second position, the tank pressure is led to the control pressure chamber 23.

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

In the piston pump 100, horsepower control is performed in which the discharge capacity (the tilting angle of the swash plate 8) of the piston pump 100 is controlled by the regulator 50 so that the discharge pressure of the piston pump 100 is kept constant.

The control spool 52 of the regulator 50 is biased to the first position by the biasing force of the assist spring 61 and the biasing force by the discharge pressure of the piston pump 100 guided to the housing chamber 65. The control spool 52 is biased to the second position by the biasing forces of the outer spring 51a and the inner spring 51 b.

In a state where the discharge pressure of the piston pump 100 and the biasing force of the assist spring 61 are kept equal to or lower than the biasing force of the outer spring 51a, the pilot spool 52 of the regulator 50 is located at the second position, and the inclination angle of the swash plate 8 is kept at the maximum (see fig. 1).

The discharge pressure of the piston pump 100 increases with an increase in the load of the hydraulic cylinder driven by the discharge pressure of the piston pump 100. When the discharge pressure of the piston pump 100 increases from the state where the tilting angle of the swash plate 8 is maintained at the maximum, the resultant force of the discharge pressure and the biasing force of the assist spring 61 is higher than the biasing force of the outer spring 51 a. Thereby, the control spool 52 moves in a direction (rightward in the drawing) to switch from the second position to the first position.

As shown in fig. 3, when the control spool 52 moves to the first position, the discharge pressure is guided from the discharge pressure passage 10 to the control pressure passage 11, and therefore, the control pressure rises. 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 with respect to the control pressure passage 11 increases. As a result, as the amount of movement of the control spool 52 in the direction (rightward in the drawing) to switch to the first position increases, the control pressure led to the control pressure passage 11 increases. Since the control pressure led to the control pressure passage 11 increases, the control piston 22 (see fig. 1) moves toward the swash plate 8, and the swash plate 8 tilts in a direction in which the tilting angle decreases. Thereby, the discharge capacity of the piston pump 100 is reduced.

When the swash plate 8 tilts in a direction in which the tilting angle decreases, the first spring seat 31 moves in the left direction in the drawing following the swash plate 8 so as to compress the outer spring 51a and the inner spring 51 b. In other words, when the swash plate 8 tilts in the direction in which the tilting angle becomes smaller, the first spring seat 31 moves toward the direction switched to the second position so as to urge the control spool 52 via the outer spring 51a (and the inner spring 51 b). Thereby, when the control spool 52 is pushed back and moved in the direction of switching to the second position, the control pressure supplied to the control pressure chamber 23 via the control pressure passage 11 decreases. When the biasing force applied to the swash plate 8 by the control pressure and the biasing force applied to the swash plate 8 from the outer spring 51a (and the inner spring 51 b) are balanced with each other with a decrease in the control pressure, the movement of the control piston 22 (tilting of the swash plate 8) is stopped. In this way, when the discharge pressure of the piston pump 100 increases, the discharge capacity decreases.

Conversely, the discharge pressure of the piston pump 100 decreases as the load of 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 resultant force of the discharge pressure of the piston pump 100 and the biasing force of the assist spring 61 acting on the control spool 52 is lower than the biasing force of the outer spring 51a and the inner spring 51 b. Thereby, the control spool 52 moves in the direction of switching from the first position to the second position. When the control spool 52 moves to the second position, the control pressure passage 11 communicates with the control passage 57 at the tank pressure, and therefore, the control pressure decreases. Since the control pressure is reduced, the swash plate 8 is tilted in the direction in which the tilt angle becomes larger by the first spring seat 31 receiving the urging forces of the outer spring 51a and the inner spring 51 b.

When the swash plate 8 tilts in the direction in which the tilt angle increases, the first spring seat 31 receiving the biasing force of the outer spring 51a and the inner spring 51b moves in the right direction in the drawing following the swash plate 8 so that the outer spring 51a and the inner spring 51b extend. Thereby, the force applied to the control spool 52 from the outer spring 51a and the inner spring 51b becomes smaller. Therefore, the pilot spool 52 receives the ejection pressure guided to the housing chamber 65 and the biasing force of the assist spring 61, and moves in the direction of compressing the outer spring 51a and the inner spring 51 b. That is, the control spool 52 moves in the direction of switching from the second position to the first position so as to follow the first spring seat 31. When the control spool 52 is again located at the first position to raise the control pressure and balance the biasing force applied to the swash plate 8 by the control pressure and the biasing force applied to the swash plate 8 from the outer spring 51a (and the inner spring 51 b), the movement of the control piston 22 (tilting of the swash plate 8) is stopped. In this way, when the discharge pressure of the piston pump 100 decreases, the discharge capacity increases.

As described above, horsepower control is performed so that the discharge pressure by the piston pump 100 increases to reduce the discharge capacity of the piston pump 100, and the discharge pressure decreases to increase the discharge capacity.

The control spool 52 moves so that the force exerted by the discharge pressure (self-pressure) of the piston pump 100, the force exerted by the outer spring 51a and the inner spring 51b, and the force exerted by the assist spring 61 are balanced, and adjusts the control pressure. Thereby, the piston pump 100 is horsepower-controlled. That is, the characteristics of the horsepower control performed by the regulator 50 are affected by the biasing force exerted by the outer spring 51a and the inner spring 51b, the biasing force exerted by the assist spring 61, and the biasing force generated by the self-pressure. By providing a plurality of structures for biasing the pilot spool 52 in this manner, the degree of freedom in design for realizing various control characteristics can be increased, and desired control characteristics can be realized with further high accuracy.

According to the above embodiment, the following effects are obtained.

In the piston pump 100, the force exerted by the assist spring 61 and the force (thrust force) exerted by the signal pressure act on the control spool 52, and therefore, various control characteristics are easily realized by the regulator 50. The housing chamber 65 serves as a signal pressure chamber that houses the assist spring 61 and is guided by a signal pressure to exert a thrust force on the pilot spool 52. Therefore, the device structure can be miniaturized as compared with the case where the signal pressure chamber is provided separately from the housing chamber 65. As a result, the piston pump 100 can realize various control characteristics by the regulator 50 while suppressing an increase in the size of the device.

In the piston pump 100, the end face 3h of the auxiliary housing portion 3f, in which the housing recess 66 is opened, is attached to the end face 3g of the housing body 3 a. Therefore, the signal pressure passage 12 can be formed in the case body 3a, not in the auxiliary case portion 3f, and therefore the auxiliary case portion 3f can be miniaturized. The signal pressure passage 12 may be formed so as to extend over the case body 3a and the auxiliary case portion 3f, and may be formed so as to open in the first recess 66a or the second recess 66b that divides the housing chamber 65. In this way, according to the piston pump 100, it is possible to arbitrarily set how the signal pressure passage 12 is connected to the housing chamber 65, and thus, the degree of freedom in design is improved.

Further, since the opening of the accommodating recess 66 in the auxiliary housing portion 3f is closed by the end face 3g of the housing body 3a, there is no need to provide a separate cap, plug, or the like for sealing the opening of the accommodating recess 66, and the number of parts can be reduced.

Next, a modification of the first embodiment will be described with reference to fig. 4.

The control spool 52 slides with respect to the spool receiving hole 50a with a predetermined sliding distance. Therefore, in the first embodiment, the working oil may flow between the housing chamber 65 and the discharge pressure passage 10 through the sliding space. In particular, when there is a pressure difference between the housing chamber 65 and the discharge pressure passage 10, the working oil tends to flow through the sliding distance.

In the first embodiment, in order to suppress the flow of the hydraulic oil between the housing chamber 65 and the discharge pressure passage 10 via the sliding distance, as shown in fig. 4, a drain chamber 13 for draining the hydraulic oil may be formed. The drain chamber 13 is connected to a fluid tank, for example. The drain chamber 13 is formed in a ring shape on the inner periphery of the spool receiving hole 50a on the opening side (left side in fig. 4) of the spool receiving hole 50a in the axial direction of the control spool 52 with respect to the discharge pressure passage 10. This allows the hydraulic oil to flow between the housing chamber 65 and the discharge pressure passage 10 via the sliding distance, and to be discharged via the drain chamber 13.

(Second embodiment)

Next, a piston pump 200 according to a second embodiment of the present invention will be described with reference to fig. 5 and 6. The following description will be mainly directed to the points different from the first embodiment, and the same reference numerals are given to the same configurations as those of the first embodiment, and the description thereof will be omitted.

In the first embodiment, the assist spring 61 is in direct contact with the flange portion 54 of the pilot spool 52, and exerts a biasing force on the pilot spool 52.

In contrast, in the second embodiment, the auxiliary biasing unit 160 further includes: a transmission pin 63 as a transmission portion that transmits the urging force of the assist spring 61 to the control spool 52; a second seating portion (seating portion) 75 on which an end portion of the assist spring 61 is seated. That is, in the second embodiment, the urging force of the assist spring 61 is exerted on the control spool 52 via the transmission pin 63.

The configuration of the second embodiment will be specifically described below.

As shown in fig. 5, in the second embodiment, the spool receiving hole 50a is opened to the end surface 3g of the housing body 3a via the end recess 50 b. The end recess 50b is a circular hole larger than the inner diameter of the spool receiving hole 50 a. The stepped surface 50c is formed by the difference in inner diameter between the spool receiving hole 50a and the end recess 50 b.

The flange 54 of the control spool 52 is accommodated in the end recess 50b. The pilot spool 52 is brought into contact with the stepped surface 50c by the flange 54, and is restricted from further movement toward the swash plate 8. That is, in the second embodiment, the stepped surface 50c functions as a stopper.

The opening of the end recess 50b with respect to the case body 3a is closed by a bottomed tubular auxiliary case portion 3 f. In the second embodiment, the end surface 3i of the auxiliary housing portion 3f on the bottom side opposite to the end surface where the accommodating recess 66 opens is attached to the end surface 3g of the housing body 3 a. The pilot spool 52 is restricted from further movement in the direction of separation from the swash plate 8 by abutting against the end surface 3i on the bottom side of the auxiliary housing portion 3 f.

The receiving recess 66 of the auxiliary housing portion 3f is opened on the opposite side of the end face 3i of the auxiliary housing portion 3f attached to the housing body 3 a. In the second embodiment, the housing recess 66 is formed as a circular hole having the same inner diameter in the axial direction. As in the first embodiment, the housing recess 66 is formed coaxially with the spool housing hole 50 a. The opening of the housing recess 66 is sealed by a cover 90 having an o-ring (not shown) attached to the outer periphery as a sealing member.

The auxiliary case portion 3f is formed with a signal pressure passage 12 that opens in the accommodation recess 66. Thereby, the signal pressure is guided to the housing chamber 65 formed by the housing recess 66 via the signal pressure passage 12.

The first seating portion 70 is accommodated in a cover hole 90a formed in the cover 90. The cover 90 is provided with an adjusting mechanism 80. Female screw holes 81 of the adjusting mechanism 80 are formed in the cover 90. The nut 83 is screwed to the screw member 82 and fastened to the cover 90, whereby the screwed position of the screw member 82 to the female screw hole 81 is fixed.

The second seating portion 75 is accommodated in the accommodating chamber 65 so as to be movable together with the assist spring 61. The second seat portion 75 moves in the housing chamber 65 in response to the movement of the control spool 52 along with the expansion and contraction of the assist spring 61.

The second seating portion 75 has: a circular plate portion 76 provided with a seating surface 76a on which the other end of the assist spring 61 is seated; and a protrusion 77 protruding from the seating surface 76a of the disk 76 and supporting the assist spring 61 from the inside.

The outer diameter of the circular plate portion 76 of the second seating portion 75 is formed smaller than the inner diameter of the accommodation recess 66 of the auxiliary case portion 3 f. Accordingly, a gap is provided between the outer periphery of the second seating portion 75 and the inner wall of the housing chamber 65 (the inner peripheral surface of the housing recess 66) in the radial direction (in other words, in the direction perpendicular to the moving direction of the control spool 52). Thereby, the second seat portion 75 can move in the housing chamber 65 in the moving direction of the control spool 52 without interfering with the inner wall of the housing chamber 65, and loss of the biasing force transmitted from the assist spring 61 to the control spool 52 can be suppressed.

The transmission pin 63 is provided between the second seat portion 75 and the control spool 52, and slidably inserted into a pin hole 65b formed in the bottom of the accommodation recess 66 of the auxiliary case 3 f. The pin hole 65b is formed coaxially with the accommodation recess 66, and one end is opened in the accommodation recess 66. The other end of the pin hole 65b opens at an end surface of the auxiliary housing portion 3f facing the end surface of the housing body 3 a.

As shown in fig. 6, the transmission pin 63 is a substantially cylindrical member, and has a pair of spherical contact portions 63a and 63b at both ends thereof. One contact portion 63a contacts the second seating portion 75 by a spherical outer surface. The other contact portion 63b is in contact with the end surface of the flange portion 54 of the pilot spool 52 by a spherical outer surface. Thus, the force transmitted from the assist spring 61 by the second seating portion 75 and the transmission pin 63 acts on the flange portion 54 of the control spool 52.

Next, the action of the spherical contact portions 63a and 63b will be described with reference to fig. 7. Fig. 7 is an enlarged schematic view of a contact portion in a state of being in contact with one contact portion 63a of the transmission pin 63 in a state where the circular plate portion 76 of the second seating portion 75 is inclined. In fig. 7, the transmission pin 163 as a comparative example and the second seating portion 75 in contact with the transmission pin 163 are shown by a broken line, and the transmission pin 163 does not have the contact portion 63a, and the end portion is formed as a flat surface perpendicular to the central axis. In fig. 7, the transmission pin 63 of the embodiment and the transmission pin 163 of the comparative example are illustrated such that the positions in the axial direction (the positions of the ends) thereof are the same.

In the transfer pin 163 of the comparative example in which the end (end surface) is formed as a flat surface, in a state in which the inclination of the second seating portion 75 is not present, the flat surface of the transfer pin 163 and the end surface of the disk portion 76 of the second seating portion 75 are in surface contact. In contrast, as shown in fig. 7, in the comparative example, even if the second seating portion 75 is slightly inclined, the transmission pin 163 is in contact with the disk portion 76 at the outer peripheral edge portion (the boundary portion between the flat surface and the outer peripheral cylindrical surface) of the end portion.

On the other hand, in the present embodiment, even if the second seating portion 75 is inclined, it is inclined along the spherical surface of the contact portion 63 a. Therefore, in the transmission pin 63 of the present embodiment, the contact portion with the disk portion 76 is not an outer peripheral portion as in the comparative example, but is a spherical portion radially inward of the outer peripheral portion. Therefore, for example, when a certain point of the opening edge portion of the pin hole 65b is considered as the reference point P0 as shown in fig. 7, the distance L1 between the contact point P1 of the transfer pin 63 and the disk portion 76 and the reference point P0 in the present embodiment is smaller than the distance L2 between the contact point P2 of the transfer pin 163 and the disk portion 76 and the reference point P0 in the comparative example (L1 < L2). As a result, the force acting around the reference point P0 is smaller in one of the transmission pins 63 according to the present embodiment than in the comparative example. Therefore, even if the second seating portion 75 is inclined in the housing chamber 65, the force pressed against the pin hole 65b is suppressed, and the increase in friction between the transmission pin 63 and the pin hole 65b is relatively small. Therefore, the transmission pin 63 can be smoothly moved, and as a result, the force can be efficiently transmitted to the control spool 52.

The transmission pin 63 is not limited to one, and may be provided in plural. When the plurality of transmission pins 63 are provided, the plurality of transmission pins 63 are preferably arranged at equal distances and at equal angular intervals with respect to the central axis of the pilot spool 52 in order to balance the force so that the pilot spool 52 does not tilt.

Even in the second embodiment described above, the housing chamber 65 functions as a signal pressure chamber that houses the assist spring 61 and is guided by the signal pressure to exert a thrust force on the pilot spool 52, as in the first embodiment. This makes it possible to realize various control characteristics by the regulator 50 while suppressing an increase in the size of the device.

In the second embodiment, the control spool 52 is subjected to the biasing force generated by the signal pressure in the housing chamber 65 according to the cross-sectional area (pressure receiving area) of the transmission pin 63. That is, since the acting force generated by the signal pressure in the housing chamber 65 can be adjusted by the cross-sectional area of the transmission pin 63, the degree of freedom in design is improved, and various control characteristics can be easily exhibited by the regulator 50. Further, for example, by setting the signal pressure introduced into the housing chamber 65 to a relatively high pressure and setting the cross-sectional area of the transmission pin 63 to a relatively small value, it is possible to exert a sufficient urging force by the pressure in the housing chamber 65 while preventing the piston pump 200 from becoming large.

In the piston pump 200, a gap is provided between the outer periphery of the second seat portion 75 of the regulator 50 and the inner wall of the housing chamber 65 in a direction perpendicular to the moving direction of the control spool 52. Accordingly, since the inner wall of the housing chamber 65 does not interfere with the movement of the second seating portion 75, the loss of the biasing force transmitted from the assist spring 61 to the control spool 52 can be suppressed.

Further, since a gap is generated between the outer periphery of the second seat portion and the inner wall of the housing chamber, the second seat portion may be inclined with respect to the moving direction of the control spool. Since the second seating portion is inclined, there is a possibility that the transmission pin is inclined in the pin hole to increase friction between the transmission pin and the auxiliary housing portion, or that the direction of force transmitted from the transmission pin to the control spool is inclined with respect to the moving direction of the control spool.

In contrast, in the present embodiment, the transmission pin 63 is brought into contact with the second seat portion 75 and the control spool 52 by the spherical contact portions 63a and 63 b. Therefore, even if the second seating portion 75 is inclined in the housing chamber 65, it is inclined with respect to the transmission pin 63 so as to follow the spherical surface of the contact portion 63a, and thus the force with which the transmission pin 63 is pressed against the pin hole 65b can be controlled to be relatively small. Therefore, the loss of the biasing force of the assist spring 61 between the transmission pin 63 and the assist housing portion 3f can be suppressed, and the biasing force of the assist spring 61 can be efficiently transmitted in the moving direction of the control spool 52 via the second seat portion 75 and the transmission pin 63.

In the piston pump 200, the force transmitted from the transmission pin 63 acts on the flange 54. In order to function as a stopper for the movement of the control spool 52, the flange portion 54 has a larger outer diameter and a larger cross-sectional area than the main body portion 53 of the control spool 52, and thus, the pressure receiving area is easily ensured. Therefore, it is easy to enlarge the diameter of the transmission pin 63 or to provide a plurality of transmission pins 63, to enlarge the pressure receiving area of the signal pressure, and to secure the thrust force generated by the signal pressure. This can further improve the degree of freedom of the control characteristics of the horsepower control of the regulator 50.

In the piston pump 200, since the portion that slides due to the signal pressure of the housing chamber 65 is only one portion between the transmission pin 63 and the pin hole 65b, leakage of the working oil from the housing chamber 65 can be suppressed to be relatively small.

(Third embodiment)

Next, a piston pump 300 according to a third embodiment of the present invention will be described with reference to fig. 8. The following description will be mainly directed to the points different from the second embodiment, and the same reference numerals are given to the same configurations as those of the second embodiment, and the description thereof will be omitted. Specifically, the configuration of only the auxiliary biasing unit 260 in the third embodiment is different from that of the auxiliary biasing unit 160 in the second embodiment, and the other configurations are the same.

In the third embodiment, as shown in fig. 8, the auxiliary biasing portion 260 includes a pair of transmission pins 63. In the third embodiment, the auxiliary biasing unit 260 further includes: a signal pressure chamber 67 that is guided to a second signal pressure different from the signal pressure guided to the housing chamber 65; a second transmission pin 68 serving as a thrust transmission portion that transmits the thrust exerted by the second signal pressure guided to the signal pressure chamber 67 to the pilot spool 52.

The pair of transmission pins 63 are provided at symmetrical positions with respect to the central axis of the pilot spool 52. The auxiliary case portion 3f has a pin hole 65b formed therein so as to correspond to the positions of the pair of transmission pins 63.

An insertion hole 65c is formed in an end surface of the auxiliary housing portion 3f facing the housing body 3a to form the signal pressure chamber 67. The second transmission pin 68 is slidably inserted into the insertion hole 65c. The insertion hole 65c is a bottomed circular hole, and a signal pressure chamber 67 is formed between the bottom of the insertion hole 65c and the end of the second transmission pin 68. The insertion hole 65c is formed coaxially with the spool receiving hole 50a and faces the end recess 50b of the spool receiving hole 50 a.

The length of the second transmission pin 68 in the axial direction is formed shorter than the depth (dimension in the axial direction) of the insertion hole 65 c. Thereby, the control spool 52 can move until it abuts against the end face of the auxiliary housing portion 3f, and even in a state where the control spool 52 abuts against the end face of the auxiliary housing portion 3f, a signal pressure chamber 67 is formed between the second transmission pin 68 and the bottom of the insertion hole 65 c.

In addition, a signal pressure passage 12 for guiding the signal pressure to the signal pressure chamber 67 is formed in the auxiliary housing 3 f. In the second embodiment, the signal pressure led to the housing chamber 65 is an external pump pressure discharged from another hydraulic pump driven by the power source together with the piston pump 300, and the second signal pressure led to the signal pressure chamber 67 is a discharge pressure (self pressure) of the piston pump 300. Since the second signal pressure is guided to the signal pressure chamber 67, the thrust force based on the second signal pressure acts on the control spool 52 via the second transmission pin 68.

In the third embodiment, the pilot spool 52 is biased in the direction of separation from the swash plate 8 (left direction in the drawing) by the biasing force of the outer spring 51a and the inner spring 51b, as in the second embodiment. The pilot spool 52 is biased in the direction approaching the swash plate 8 by the biasing force of the assist spring 61, the thrust force generated by the external pump pressure (signal pressure) guided to the housing chamber 65, and the thrust force generated by the discharge pressure (second signal pressure) of the piston pump 100 guided to the second signal pressure chamber. That is, the control spool 52 moves so as to balance the discharge pressure of the outer spring 51a, the inner spring 51b, the assist spring 61, the piston pump 300, and the force generated by the external pump pressure.

In comparison with the second embodiment, in the third embodiment, the discharge pressure of the piston pump 300 and the external pump pressure each exert a thrust force that biases the pilot spool 52 as signal pressures, and thus more complicated horsepower control characteristics can be realized. In the third embodiment, in addition to the second embodiment of guiding the discharge pressure of the piston pump 300, the pilot spool 52 is biased toward the swash plate 8 by the external pump pressure. In this way, the thrust force generated by the self-pressure is supplemented by the external pump pressure, and therefore, in the third embodiment, the self-pressure at which horsepower control is performed is smaller by an amount equivalent to the magnitude of the external pump pressure than in the second embodiment. As described above, in the third embodiment, the mechanism for biasing the control spool 52 is provided in addition to the second embodiment, and therefore, the degree of freedom in designing the horsepower control characteristic is improved.

In the third embodiment, the number of the transmission pins 63 is not limited to one, and may be single or three or more. The second transmission pins 68 are not limited to a single one, and may be plural.

In the third embodiment, the self-pressure may be guided to the housing chamber 65, and the external pump pressure may be guided to the signal pressure chamber 67. The signal pressure to be led to the housing chamber 65 and the second signal pressure to be led to the signal pressure chamber 67 are not limited to the pressure in the above embodiment, and may be other pressures. For example, the second signal pressure led to the signal pressure chamber 67 may be a pressure obtained by adjusting the self-pressure or the external pump pressure by a solenoid valve. The second signal pressure may be switched between supply to and shut off from the signal pressure chamber 67 by an on-off valve.

(Fourth embodiment)

Next, a piston pump 400 according to a fourth embodiment of the present invention will be described with reference to fig. 9. The following description will be mainly directed to the points different from the first embodiment, and the same reference numerals are given to the same configurations as those of the first embodiment, and the description thereof will be omitted.

In the first embodiment described above, the regulator 50 implements horsepower control that adjusts the control pressure in accordance with the load of the drive source that drives the piston pump 100. Specifically, the self-pressure of the piston pump 100 is thus guided to the housing chamber 65 of the regulator 50 as the signal pressure.

In contrast, in the piston pump 400 according to the fourth embodiment, as shown in fig. 9, the pressure generated by adjusting the pressure from the hydraulic pressure source 103 such as a gear pump by the electromagnetic proportional pressure reducing valve 101 is led to the regulator 50 as the signal pressure.

The opening degree of the electromagnetic proportional pressure reducing valve 101 is adjusted by an electric signal output from the controller 102, for example, according to an operation by an operator. With this configuration, the inclination angle of the swash plate 8 can be controlled by an electric signal, and thus, an arbitrary control characteristic can be realized according to an operation by an operator. That is, the piston pump 400 according to the fourth embodiment does not perform horsepower control, and the piston pump according to the present invention is not limited to the pump that performs horsepower control.

In the piston pump 400 according to the fourth embodiment, as shown in fig. 9, the biasing member is preferably constituted by a single spring 51 c. By doing so, the electromagnetic proportional pressure reducing valve 101 is proportional controlled in accordance with the linear characteristic of the spring 51c, and control can be easily performed.

In the fourth embodiment, a high-pressure selector valve 104 is provided that selects a high pressure of the pressure supplied from the hydraulic pressure source 103 and the self pressure of the piston pump 400 and guides the selected high pressure to the discharge pressure passage 10. Accordingly, for example, even in a state where the self pressure of the piston pump 400 is relatively low, such as when the piston pump 400 is started, the hydraulic pressure source 103 guides a predetermined pressure to the discharge pressure passage 10, and therefore, the inclination angle of the swash plate 8 can be controlled.

In addition, as in the first embodiment, the high-pressure selector valve 104 may not be provided, and the self-pressure of the piston pump 400 or the pressure of the hydraulic pressure source 103 such as a gear pump may be led to the discharge pressure passage 10 alone. In addition, the hydraulic pressure source 103 and the high-pressure selector valve 104 may be applied to the first to third embodiments described above.

In the fourth embodiment, the signal pressure is generated by the electromagnetic proportional pressure reducing valve 101, and horsepower control may be performed in the same manner as in the first, second, and third embodiments. In the specific description, the opening degree of the electromagnetic proportional pressure reducing valve 101 is adjusted according to the load of the drive source of the piston pump 400, the pressure of the hydraulic pressure source 103 or the self pressure is reduced to generate a signal pressure, and the signal pressure is led to the housing chamber 65, whereby horsepower control can be performed. For example, when the drive source is an engine, the controller 102 may calculate the load of the drive source from the engine torque, the engine speed, or the like, adjust the opening degree of the electromagnetic proportional pressure reducing valve 101 according to the load, generate the signal pressure, and guide the signal pressure to the housing chamber 65. For example, when the drive source is an electric motor, the controller 102 may calculate the load of the drive source from the torque or the rotational speed of the electric motor, adjust the opening degree of the electromagnetic proportional pressure reducing valve 101 according to the load, generate the signal pressure, and guide the signal pressure to the housing chamber 65. The horsepower control can be controlled electrically by adjusting the opening degree of the electromagnetic proportional pressure reducing valve 101 according to the load of the drive source to generate a signal pressure.

In this way, the control of the horsepower by the electric control can be performed by generating the signal pressure by the electromagnetic proportional pressure reducing valve 101, or the control of the tilting angle of the swash plate 8 other than the horsepower control can be performed by a signal other than the load of the drive source based on the operation of the operator or the like. For example, in the second embodiment and the third embodiment, the inclination angle of the swash plate 8 may be controlled not by horsepower control but by the electromagnetic proportional pressure reducing valve 101. In the third embodiment, the second signal pressure may be the signal pressure generated by the electromagnetic proportional pressure reducing valve 101 according to the load of the drive source.

The structure, operation, and effects of the embodiments of the present invention will be summarized below.

The piston pumps 100, 200, 300, 400 include: a cylinder 2 which rotates together with the shaft 1; a plurality of cylinders 2b formed at the cylinder block 2 and configured to have a predetermined interval in the circumferential direction of the shaft 1; a piston 5 slidably inserted into the cylinder 2b, and defining a volume chamber 6 inside the cylinder 2 b; a swash plate 8 capable of tilting and reciprocating the piston 5 to expand and contract the volume chamber 6; a first urging portion 20 that urges the swash plate 8 according to the supplied control pressure; a second urging portion 30 that urges the swash plate 8 against the first urging portion 20; a regulator 50 that controls the control pressure that is guided to the first urging portion 20, the regulator 50 including: a biasing member (an outer spring 51a and an inner spring 51 b) that expands and contracts in accordance with tilting of the swash plate 8; a control spool 52 that moves in accordance with the biasing force of the biasing member to adjust the control pressure; an auxiliary biasing member (auxiliary spring 61) that exerts a biasing force on the control spool 52 so as to overcome the biasing force of the biasing member; a housing chamber 65 for housing the auxiliary biasing member, and a signal pressure for generating a thrust force against the control spool 52 so as to overcome the biasing force of the biasing member is guided to the housing chamber 65.

In this configuration, the signal pressure is guided to the housing chamber 65, and the housing chamber 65 houses the auxiliary biasing member for biasing the control spool 52, so that the signal pressure also exerts a thrust force on the control spool 52. The housing chamber 65 functions as a pressure chamber for generating a thrust by the signal pressure in addition to the auxiliary biasing member, and thus can be miniaturized as compared with the case where the housing chamber 65 and the pressure chamber are provided separately. Thus, even if the structure for biasing the pilot spool 52 is provided, the device can be prevented from being enlarged. Therefore, the degree of freedom of the control characteristics by the regulator 50 can be improved while suppressing an increase in the size of the piston pumps 100, 200, 300.

In the piston pumps 100 and 400 according to the first embodiment, the auxiliary biasing member directly contacts the pilot spool 52 to exert a biasing force.

In this structure, the structure can be simplified, and the number of parts can be reduced.

In the piston pumps 200 and 300 according to the second and third embodiments, the regulator 50 further includes: a seating portion (second seating portion 75) on which one end of the auxiliary biasing member is seated, the seating portion being provided in the housing chamber 65 so as to be movable in the moving direction of the control spool 52; and a transmission unit (transmission pin 63) provided between the seat unit and the pilot spool 52 and transmitting the biasing force of the auxiliary biasing member to the pilot spool 52.

In this configuration, the control spool 52 exerts a biasing force by the signal pressure in the housing chamber 65 according to the cross-sectional area (pressure receiving area) of the transmission portion. That is, since the acting force generated by the signal pressure in the housing chamber 65 can be adjusted by the cross-sectional area of the transmission pin 63, the degree of freedom in design is improved, and various control characteristics can be easily exhibited by the regulator 50.

In the piston pumps 200 and 300 according to the second and third embodiments, the seating portion is provided so as to be spaced apart from the inner wall of the housing chamber 65 in the direction perpendicular to the moving direction of the pilot spool 52.

In this configuration, the seating portion moves in the housing chamber 65 so as not to contact the inner wall of the housing chamber 65, and therefore, friction force between the seating portion and the housing chamber 65 can be suppressed from affecting the control characteristics.

In the piston pumps 200 and 300 according to the second and third embodiments, the transmission portion has the contact portion 63a formed in a spherical shape and in contact with the seating portion.

In this configuration, even if the seating portion is inclined in the housing chamber 65 due to the clearance provided between the seating portion and the housing chamber 65, the contact portion 63a of the transmission portion with respect to the seating portion is spherical, and therefore, it is difficult to prevent the transmission pin 63 from moving in the moving direction of the control spool 52.

In the piston pump 300 according to the third embodiment, the auxiliary biasing unit 260 further includes: a signal pressure chamber 67 that is guided to a second signal pressure different from the signal pressure guided to the housing chamber 65; and a thrust transmitting portion (second transmitting pin 68) that transmits the thrust generated by the second signal pressure being guided to the signal pressure chamber 67 to the pilot spool 52.

In this structure, in addition to the urging force of the auxiliary urging member and the urging force generated by the signal pressure, the urging force generated by the second signal pressure acts on the pilot spool 52. Therefore, more various control characteristics can be realized.

The piston pumps 100, 200, 300, 400 have a housing 3 provided with a spool receiving hole 50a into which the pilot spool 52 is inserted, and the pilot spool 52 has: a body portion 53 in sliding contact with the spool receiving hole 50 a; a flange portion 54 provided at an end of the main body portion 53 and having a larger outer diameter than the main body portion 53, wherein the flange portion 54 is configured to abut against a stopper portion (an end surface 3g and a stepped surface 50c of the housing body 3 a) provided in the housing 3 in accordance with movement of the pilot spool 52, thereby restricting further movement of the pilot spool 52 along the biasing force exerted by the auxiliary biasing member, and the biasing force of the auxiliary biasing member and the pushing force generated by the signal pressure are configured to act on the flange portion 54.

According to this structure, in the control spool 52, the flange portion 54 having a relatively large cross-sectional area is provided at the end portion of the body portion 53. By configuring the control spool 52 such that a force acts on the flange 54, the area of the control spool 52 to which the force is applied can be ensured. Thus, the force is easily applied to the control spool 52 by a plurality of configurations, and a control characteristic of more various horsepower control can be realized.

The signal pressure of the piston pump 400 is generated by the electromagnetic proportional pressure reducing valve 101.

In this configuration, the inclination angle control of the swash plate can be performed by an electric signal.

The embodiments of the present invention have been described above, but the above embodiments merely represent some application examples of the present invention, and do not limit the technical scope of the present invention to the specific configurations of the above embodiments.

In the first embodiment described above, the flange portion 54 of the control spool 52 is accommodated in the first recess 66a of the accommodation recess 66 of the auxiliary housing portion 3f, and the end surface 3g of the housing body 3a functions as a stopper portion that restricts movement of the control spool 52. In the second and third embodiments, the flange 54 is accommodated in the end recess 50b of the housing body 3a, and the stepped surface 50c between the end recess 50b and the spool accommodating hole 50a functions as a stopper. In contrast, in the first embodiment, the end portion concave portion 50b and the stepped surface 50c may be provided in the case body 3a as in the second and third embodiments. In the second and third embodiments, the flange 54 may be housed by providing a recess in the end surface facing the case body 3a, as in the first recess 66a of the first embodiment. In this way, the recess for accommodating the flange 54 and the stopper portion abutting against the flange 54 may be provided in the case 3, and may be provided in the case body 3a or the auxiliary case 3f. Further, recesses for accommodating the flange 54 may be provided in both the case body 3a and the auxiliary case portion 3f.

In the second and third embodiments, the transmission pins 63 and 68 have spherical contact portions 63a, 63b, and 68a. The configuration having the spherical contact portions 63a, 63b, 68a is not essential, and the transmission pin 63 and the second transmission pin 68 may be in surface contact with the second seating portion 75 and the flange portion 54 of the control spool 52 via flat surfaces.

In the second and third embodiments, a gap in the radial direction of the control spool 52 is provided between the outer periphery of the second seat portion 75 and the inner wall of the housing chamber 65 (the inner periphery of the housing recess 66). In contrast, the second seating portion 75 may be in sliding contact with the inner periphery of the accommodating recess 66. In this case, the housing chamber 65 is partitioned into two rooms by the second seating portion 75. The two rooms may also be guided to the same hydraulic pressure as each other by communicating with each other through the communication hole formed in the second seating portion 75, or by guiding the signal pressure from the signal pressure passage 12, respectively. In addition, the signal pressures different from each other may be guided to the two rooms partitioned by the second seating portion 75 in the housing chamber 65. In this case, the pressure of the room (the room in which the transmission pin 63 is accommodated) separated between the second seating portion 75 and the bottom of the accommodation recess 66 of the two rooms may be set to be relatively low with respect to the other room. With this configuration, even when the second seating portion 75 is in sliding contact with the housing recess 66, the biasing force of the assist spring 61 can be transmitted to the control spool 52 via the second seating portion 75 and the transmission pin 63.

Claims (7)

1. A hydraulic rotary machine is provided with:

A cylinder block that rotates together with the drive shaft;

a plurality of cylinders formed at the cylinder block and configured to have a predetermined interval in a circumferential direction of the drive shaft;

a piston slidably inserted into the cylinder and defining a volume chamber inside the cylinder;

a swash plate capable of tilting and reciprocating the piston to expand and contract the volume chamber;

a first urging portion that urges the swash plate according to a supplied control pressure;

a second urging portion that urges the swash plate so as to overcome the first urging portion;

a regulator that controls the control pressure that is guided to the first urging portion,

The regulator has:

a biasing member that expands and contracts in response to tilting of the swash plate;

A control spool that moves in accordance with the urging force of the urging member to adjust the control pressure;

An auxiliary biasing member that exerts a biasing force on the control spool so as to overcome the biasing force of the biasing member;

a housing chamber for housing the auxiliary biasing member,

A signal pressure that generates a thrust force with respect to the control spool so as to overcome the biasing force of the biasing member is guided to the housing chamber.

2. The hydraulic rotary machine according to claim 1, wherein,

The auxiliary biasing member directly contacts the pilot spool to exert a biasing force.

3. The hydraulic rotary machine according to claim 1, wherein,

The regulator further has:

A seating portion provided in the housing chamber so that one end of the auxiliary biasing member is seated and movable in a moving direction of the control spool;

And a transmission unit that is provided between the seating unit and the control spool and transmits the biasing force of the auxiliary biasing member to the control spool.

4. The hydraulic rotary machine according to claim 3, wherein,

The seating portion is provided so as to be spaced apart from an inner wall of the housing chamber in a direction perpendicular to a moving direction of the pilot spool.

5. The hydraulic rotary machine according to claim 3 or 4, wherein,

The transmission portion has a contact portion formed in a spherical shape and in contact with the seating portion.

6. The hydraulic rotary machine according to any one of claims 1 to 4, wherein,

Has a housing provided with a spool receiving hole into which the control spool is inserted,

The control spool has:

a body portion in sliding contact with the spool receiving hole;

a flange portion provided at an end portion of the body portion and formed of an outer diameter larger than that of the body portion,

The flange portion is abutted with a limit portion arranged on the shell according to the movement of the control slide valve, thereby limiting the further movement of the control slide valve along the acting force exerted by the auxiliary force application component,

And the urging force of the auxiliary urging member acts on the flange portion.

7. The hydraulic rotary machine according to any one of claims 1 to 4, wherein,

The signal pressure is generated by an electromagnetic proportional pressure reducing valve.