Pump control pressure regulator

Abstract

The present application relates to a pump control pressure regulator. The regulator (50) is provided with: a housing main body (3a) having a control pressure passage (11), an injection pressure passage (10), and a signal pressure passage (13); a sleeve (60) mounted to a mounting hole (67) of the housing main body and having a first port (60a), a second port (60b), and a third port (60c); and a control spool (52) housed in the sleeve in a freely slidable manner and displaced in an axial direction in accordance with an injection pressure supplied through the second port and a signal pressure supplied through the third port, a drain passage (63) being provided on the sleeve and opening between a second connection portion (82) at which the injection pressure passage and the second port are connected and a third connection portion (83) at which the signal pressure passage and the third port are connected.

Description

Technical Field

[0001] This invention relates to a pump control pressure regulator. Background Technology

[0002] Japanese Patent Application Publication No. JP2008-240518A discloses a pump control pressure regulator that supplies horsepower control pressure to a swashplate piston pump that controls the drive horsepower based on a horsepower control pressure. The horsepower control pressure supplied to the swashplate piston pump from this pump control pressure regulator is changed according to a signal pressure supplied from an external source.

[0003] In the pump control pressure regulator described in Japanese Patent Application Publication No. JP2008-240518A, an outlet pressure port that guides the discharge pressure of a swashplate piston pump and a signal pressure port that guides a signal pressure from an external source are arranged adjacently. When the outlet pressure port that guides a higher pressure and the signal pressure port that guides a lower pressure are arranged adjacently, working oil may leak from the connection between the outlet pressure port and the passage formed in the pump housing and flow into the signal pressure port. When the higher pressure working oil flows into the signal pressure port, even when no signal pressure is supplied from the outside, the state is the same as when a signal pressure is supplied. Therefore, an unexpectedly large amount of horsepower control pressure is supplied to the swashplate piston pump from the pump control pressure regulator.

[0004] When the horsepower control pressure supplied to the swashplate piston pump from the pump control pressure regulator becomes unexpectedly high, for example, the pump's injection volume may decrease, resulting in insufficient working oil supply to the hydraulic equipment. Additionally, if the swashplate piston pump is driven by an engine, the pump's driving horsepower may increase, overloading the engine and causing it to stop. Summary of the Invention

[0005] The purpose of this invention is to prevent situations where unexpectedly large horsepower control pressures are supplied to the pump from the pump control pressure regulator.

[0006] According to one aspect of the present invention, a pump control pressure regulator that supplies the horsepower control pressure to a pump whose drive horsepower is controlled according to a horsepower control pressure comprises: a housing having a first passage for guiding the horsepower control pressure to the pump, a second passage for guiding the pump's ejection pressure, a third passage for guiding a signal pressure lower than the ejection pressure that modifies the pump's horsepower, and a mounting hole for opening the first passage, the second passage, and the third passage; a sleeve mounted in the mounting hole and having a first port communicating with the first passage, a second port communicating with the second passage, and a third port communicating with the third passage; a control slide valve that is slidably housed in the sleeve and axially displaced according to the ejection pressure supplied via the second port and the signal pressure supplied via the third port, thereby allowing or cutting off the communication between the first port and the second port; a drain passage communicating with a fluid tank storing working fluid is provided on either the housing or the sleeve, the drain passage opening between a second connection portion connecting the second passage and the second port, and a third connection portion connecting the third passage and the third port. Attached Figure Description

[0007] Figure 1 A cross-sectional view of a swashplate pump including the pump control pressure regulator according to an embodiment of the present invention.

[0008] Figure 2 For along Figure 1 A sectional view along line II-II in the diagram.

[0009] Figure 3 To be along Figure 2 An enlarged sectional view showing the cross section of line III-III.

[0010] Figure 4 The diagram shows a modified example of a swashplate pump including the pump control pressure regulator according to an embodiment of the present invention. It is intended to represent a pump equivalent to... Figure 2 A sectional view of the cross section. Detailed Implementation

[0011] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] Reference Figure 1 The following description pertains to a swashplate pump 100 (hereinafter referred to as "pump 100") equipped with a pump control pressure regulator 50 (hereinafter referred to as "regulator 50") according to an embodiment of the present invention. Pump 100 is used as a hydraulic supply source to supply working oil as a working fluid to hydraulic equipment such as a hydraulic cylinder, and is driven by a drive source such as an engine.

[0013] like Figure 1 As shown, the pump 100 is a swashplate piston pump and includes: a shaft 1 that serves as a drive shaft and is rotated by a power source; a cylinder 2 that is connected to the shaft 1 and rotates together with the shaft 1; and a housing 3 that houses the cylinder 2.

[0014] The housing 3 has: a bottomed cylindrical body 3a serving as the outer shell; and a cover 3b that seals the open end of the housing body 3a. The interior of the housing 3 is connected to a fluid tank (not shown) for storing working oil via a drain pipe (not shown). Therefore, the pressure inside the housing 3 is approximately equal to the pressure in the fluid tank.

[0015] A through hole 3c is formed on the cover 3b for inserting the shaft 1, which is supported in the through hole 3c by a bearing 4a so as to allow free rotation. A power source such as an engine (not shown) is connected to one end 1a of the shaft 1 that protrudes outward from the cover 3b. The other end 1b of the shaft 1, which is inserted into the interior of the housing 3, is received in a shaft receiving hole 3d provided at the bottom of the housing body 3a, and is supported in the shaft receiving hole 3d so as to allow free rotation by a bearing 4b. In addition, the shaft of another hydraulic pump, such as a gear pump, which is driven by a power source together with the pump 100, is connected to the other end 1b of the shaft 1.

[0016] The cylinder body 2 has a through hole 2a through which the shaft 1 passes, and is splinedly engaged with the shaft 1 through the through hole 2a. In this way, the cylinder body 2 rotates along with the shaft 1.

[0017] Multiple cylinders 2b are formed on the cylinder body 2, parallel to the shaft 1, each having an opening on one end face. The multiple cylinders 2b are formed at predetermined intervals in the circumferential direction of the cylinder body 2. A cylindrical piston 5, which divides the volume chamber 6, is inserted into the cylinder 2b in a freely reciprocating manner. 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.

[0018] The pump 100 also includes: a slide 7, which is connected to the spherical seat 5a of the piston 5 in a freely rotatable manner and slides in contact with the spherical seat 5a; a swashplate 8, which slides in contact with the slide 7 as the cylinder 2 rotates; and a valve plate 9, which is disposed between the bottom surface of the cylinder 2 and the housing body 3a.

[0019] The sliding track 7 includes: a receiving portion 7a that receives a spherical seat 5a formed on the top of each piston 5; and a circular flat plate portion 7b that slides in contact with the sliding contact surface 8a of the inclined plate 8. The inner surface of the receiving portion 7a is spherical and slides in contact with the outer surface of the received spherical seat 5a. This allows the sliding track 7 to be angularly displaced relative to the spherical seat 5a in all directions.

[0020] The inclined plate 8 is supported on the cover 3b in a tilting manner so that the discharge volume of the pump 100 can be varied.

[0021] The valve plate 9 is a circular plate component that allows the base end face of the cylinder 2 to slide in contact with it, and is fixed to the bottom of the housing body 3a. On the valve plate 9, there is an intake port (omitted from the figure) that connects the intake passage (not shown) formed in the cylinder 2 to the volume chamber 6, and an exhaust port (omitted from the figure) that connects the exhaust passage (omitted from the figure) formed in the cylinder 2 to the volume chamber 6.

[0022] In addition, such as Figure 1 as well as Figure 2 As shown, the pump 100 further includes: a first force-applying mechanism 20, which applies force to the inclined plate 8 in the direction where the tilt angle decreases; a second force-applying mechanism 30, which applies force to the inclined plate 8 in the direction where the tilt angle increases; and a regulator 50, which supplies horsepower control pressure (hereinafter referred to as "control pressure") to the first force-applying mechanism 20. Additionally, Figure 2 To be along Figure 1 An enlarged sectional view showing a portion of the cross section along line II-II.

[0023] like Figure 1 As shown, the first force-applying mechanism 20 has: a large-diameter piston 22, which is inserted into the first piston receiving hole 21 formed on the housing body 3a in a free sliding manner and abuts against the inclined plate 8; and a control pressure chamber 23, which is divided into the first piston receiving hole 21 by the large-diameter piston 22.

[0024] The control pressure regulated by the regulator 50 is directed to the control pressure chamber 23. That is, the large-diameter piston 22 of the first force application mechanism 20 is displaced according to the control pressure supplied from the regulator 50, so as to change the tilt angle of the inclined plate 8, and applies force to the inclined plate 8 in the direction that the higher the control pressure, the smaller the tilt angle.

[0025] like Figure 2 As shown, the second force-applying mechanism 30 includes: a small-diameter piston 32, which is freely slidably inserted into a second piston receiving hole 31 formed on the housing body 3a and abuts against the inclined plate 8; and a pressure chamber 33, which is divided within the second piston receiving hole 31 by the small-diameter piston 32. Additionally, although in Figure 2 Not shown in the figure, however, the end of the small-diameter piston 32 opposite to the end facing the pressure chamber 33 abuts against the inclined plate 8.

[0026] The ejection pressure of pump 100 is always guided to pressure chamber 33 via ejection pressure passage 10 formed on housing body 3a. The small-diameter piston 32 of second force application mechanism 30 is subjected to the ejection pressure guided to pressure chamber 33, and is displaced in a manner that changes the tilt angle of inclined plate 8, and applies force to inclined plate 8 in the direction that the higher the ejection pressure, the smaller the tilt angle.

[0027] In addition, the outer diameter of the large-diameter piston 22 is larger than that of the small-diameter piston 32, and the pressure-bearing area of ​​the large-diameter piston 22, which is guided to the control pressure chamber 23, is larger than that of the small-diameter piston 32, which is guided to the pressure chamber 33.

[0028] The regulator 50 mainly adjusts the control pressure guided to the control pressure chamber 23 based on the discharge pressure of the pump 100, and is set up to control the output of the pump 100, that is, the horsepower required to drive the pump 100.

[0029] The regulator 50 includes: a feedback pin 40 that moves axially following the inclination of the inclined plate 8; a force-applying member 51 that applies force to the feedback pin 40 toward the inclined plate 8; a control slide valve 52 that moves according to the ejection pressure of the pump 100 and the force of the force-applying member 51, and adjusts the control pressure; a sleeve 60 that has a slide valve receiving hole 65 for receiving the control slide valve 52 and is mounted in a mounting hole 67 formed on the housing body 3a; a plug 70 that seals one end of the slide valve receiving hole 65 formed on the sleeve 60; and a cylindrical shaft member 71, one end of which is configured to abut against the plug 70 and the other end of which is inserted into the control slide valve 52.

[0030] The feedback pin 40 is a rod-shaped component and is inserted into the through hole 41 in a freely sliding manner. The through hole 41 is formed in the housing body 3a in an axially penetrating manner. The feedback pin 40 is subjected to force by the force-applying component 51 in such a way that one end abuts against the inclined plate 8.

[0031] The force-applying component 51 includes: an outer spring 51a; and an inner spring 51b, the inner spring having a smaller winding diameter than the outer spring 51a and being disposed inside the outer spring 51a. Both the outer spring 51a and the inner spring 51b are helical springs and are clamped between a first spring seat 72 and a second spring seat 73. The first spring seat 72 engages with the spherical end of the feedback pin 40, and the second spring seat 73 engages with the end of the control slide valve 52.

[0032] The natural length (free length) of the outer spring 51a is set to be longer than that of the inner spring 51b, and is in the state where the tilt angle of the inclined plate 8 is at its maximum. Figure 1In the state shown, the outer spring 51a is compressed between the first spring seat 72 and the second spring seat 73, while the inner spring 51b is compressed at either end from the spring seat (as shown). Figure 1 The first spring seat 72) is in a state of separation and floating, that is, in its natural length state.

[0033] That is, as the tilt angle of the inclined plate 8 decreases from its maximum state, initially only the outer spring 51a is compressed. When the outer spring 51a is compressed to a state shorter than the natural length of the inner spring 51b, both the outer spring 51a and the inner spring 51b are compressed. Thus, the elastic force acting on the outer spring 51a and the inner spring 51b of the inclined plate 8 via the feedback pin 40 gradually increases as the tilt angle of the inclined plate 8 decreases.

[0034] The mounting hole 67 for the sleeve 60 is a through hole formed in the housing body 3a with one end open relative to the interior of the housing 3 and extending axially. Figure 2 As shown, the inner circumferential surface of the mounting hole 67 has openings for a control pressure passage 11, which guides control pressure to the control pressure chamber 23 as a first passage; an ejection pressure passage 10, which guides the ejection pressure of the pump 100 as a second passage; and a signal pressure passage 13, which guides the signal pressure supplied from the outside as a third passage.

[0035] The sleeve 60 is a cylindrical component with a valve receiving hole 65 for inserting the control valve 52, formed in a through-hole manner in the axial direction. For example... Figure 2 As shown, the slide valve receiving hole 65 has: a first hole 65a, which supports the control slide valve 52 to slide freely; and a second hole 65b, the inner diameter of which is larger than that of the first hole 65a. The slide valve receiving hole 65 is sealed by screwing the plug 70 into the second hole 65b.

[0036] Inside the second hole 65b, sealed at the open end by the plug 70, is a recovery chamber 66 for recovering working oil leaking from the gap between the sleeve 60 and the control slide valve 52 and the gap between the control slide valve 52 and the shaft component 71. Furthermore, to allow the working oil recovered in this recovery chamber 66 to return to the fluid tank, a recovery passage 62 is formed on the sleeve 60. The recovery passage 62 consists of a plurality of through holes formed along the axial direction of the sleeve 60, with one end opening into the recovery chamber 66, and the other end opening relative to the interior of the housing 3.

[0037] On the outer periphery of the sleeve 60, starting from the end facing the interior of the housing 3, a first port 60a, a second port 60b, and a third port 60c are sequentially formed to form an annular groove. Additionally, on the sleeve 60, a first connecting hole 61a, a second connecting hole 61b, and a third connecting hole 61c are formed, respectively communicating with the first port 60a, the second port 60b, and the third port 60c, to serve as radially penetrating through holes. The first connecting hole 61a, the second connecting hole 61b, and the third connecting hole 61c open on the inner peripheral surface of the first hole portion 65a.

[0038] With the sleeve 60 installed in the mounting hole 67, the first port 60a is connected to the control pressure passage 11, which guides control pressure to the control pressure chamber 23; the second port 60b is connected to the injection pressure passage 10, which continuously guides the injection pressure of the pump 100; and the third port 60c is connected to the signal pressure passage 13. Furthermore, the signal pressure guided to the signal pressure passage 13 is, for example, the oil pressure injected from another pump driven by a power source along with the pump 100. When this signal pressure is changed, as described later, the tilt angle of the swashplate 8 changes, thereby altering the injection volume of the pump 100 and thus changing the drive horsepower characteristics of the pump 100.

[0039] like Figure 2 As shown, the control slide valve 52 includes: a main body 53, which is slidably supported by a first hole 65a of a slide valve receiving hole 65; a flange 54, which is provided at one end of the main body 53 and has a larger outer diameter than the main body 53; and a protrusion 55, which is provided at the end opposite to the flange 54 and is inserted into a second spring seat 73. The outer diameter of the protrusion 55 is formed to be smaller than that of the main body 53, and the stepped surface 55a formed by the difference in outer diameter between the main body 53 and the protrusion 55 abuts against the second spring seat 73.

[0040] On the outer periphery of the main body 53, starting from the protrusion 55 side, a first control port 56a, a second control port 56b, and a third control port 56c are formed sequentially to form an annular groove. Additionally, on the control slide valve 52, a first control passage 57a, a second control passage 57b, and a third control passage 57c are formed, respectively communicating with the first control port 56a, the second control port 56b, and the third control port 56c, to form a through hole extending radially through the valve.

[0041] Furthermore, an axial passage 58a, with one end open at the top surface of the protrusion 55 and the other end connected to the first control passage 57a, is formed axially on the control slide valve 52. The axial passage 58a is provided to connect the first control passage 57a to the interior of the housing 3 together with the connecting passage 73a formed in the second spring seat 73. In other words, the first control passage 57a is connected to the interior of the housing 3 via the axial passage 58a and the connecting passage 73a, and the pressure within the first control passage 57a is the same as the pressure in the fluid tank.

[0042] Furthermore, on the control slide valve 52, a first insertion hole 58b opening at the end on the plug 70 side and a second insertion hole 58c continuously disposed therefrom are formed coaxially along the axial direction. The first insertion hole 58b has a length extending axially to the third control passage 57c, and the second insertion hole 58c has a length extending axially to the second control passage 57b. The inner diameter of the first insertion hole 58b is formed to be larger than the inner diameter of the second insertion hole 58c. A large-diameter portion 71a formed on the base end side of the shaft member 71 abutting against the plug 70 is slidably inserted into the first insertion hole 58b, and a small-diameter portion 71b, smaller in diameter than the large-diameter portion 71a and formed on the top end side of the shaft member 71, is slidably inserted into the second insertion hole 58c. Additionally, although the shaft member 71 inserted into the control slide valve 52 is formed from a different component than the plug 70, it may also be integrally formed with the plug 70.

[0043] like Figure 2 As shown, with the flange 54 of the control slide valve 52 abutting against the plug 70, the second control passage 57b opens in the ejection pressure chamber 59a defined by the second insertion hole 58c and the end face of the small diameter portion 71b inserted into the second insertion hole 58c.

[0044] Since the second control passage 57b is always connected to the ejection pressure passage 10 via the second control port 56b, the second connecting hole 61b, and the second port 60b, the ejection pressure of the pump 100 is always guided to the ejection pressure chamber 59a. The ejection pressure guided to the ejection pressure chamber 59a via the second control passage 57b operates in such a way that the ejection pressure chamber 59a expands, that is, in a way that the small diameter portion 71b is forced out from the second insertion hole 58c. In other words, the control slide valve 52 is pressed in a direction away from the plug 70 in the axial direction by the pressure of the working oil guided to the ejection pressure chamber 59a, that is, in a direction that compresses the outer spring 51a and the inner spring 51b.

[0045] In addition, such as Figure 2As shown, when the flange 54 of the control slide valve 52 abuts against the plug 70, the first control passage 57c opens in the signal pressure liquid chamber 59b defined by the stepped surface 71c formed by the difference in outer diameters of the large diameter portion 71a and the small diameter portion 71b, the first insertion hole 58b, and the outer peripheral surface of the small diameter portion 71b.

[0046] Since the third control passage 57c is always connected to the signal pressure passage 13 via the third control port 56c, the third connecting hole 61c, and the third port 60c, the signal pressure supplied from the outside is always guided to the signal pressure chamber 59b. The signal pressure guided to the signal pressure chamber 59b via the third control passage 57c operates in such a way that the signal pressure chamber 59b expands, that is, in a way that the large-diameter portion 71a is forced out from the first insertion hole 58b. In other words, the control slide valve 52 is pressed in a direction away from the plug 70 in the axial direction by the pressure of the working oil guided to the signal pressure chamber 59b, that is, in a direction that compresses the outer spring 51a and the inner spring 51b.

[0047] Thus, the control valve 52 is moved away from the inclined plate 8 by the force generated by the outer spring 51a and the inner spring 51b. Figure 2 The force is applied to the left (center), and on the other hand, it is directed towards the inclined plate 8 by ejection pressure and signal pressure. Figure 2 (The middle direction is to the right) is subjected to force. That is, the control slide valve 52 moves relative to the sleeve 60 towards a position in which the force applied by the force-applying component 51, which is composed of the outer spring 51a and the inner spring 51b, the force generated by the ejection pressure of the pump 100 guided to the ejection pressure chamber 59a, and the force generated by the signal pressure guided to the signal pressure chamber 59b are balanced.

[0048] Specifically, the control valve 52 moves between two positions: a first position where the flange 54 abuts against the stepped portion 65c formed between the first hole 65a and the second hole 65b, and a second position where the flange 54 abuts against the plug 70. Additionally, in Figure 1 as well as Figure 2 The image shows the state where the control slide valve 52 is in the second position. The position of the control slide valve 52 is controlled by the control slide valve 52 from... Figure 1 as well as Figure 2 The second position shown in the diagram moves to the right and switches to the first position.

[0049] In the first position, the first connecting hole 61a and the second connecting hole 61b of the sleeve 60 are connected via the second control port 56b of the control slide valve 52, and the connection between the first control passage 57a of the control slide valve 52 and the first connecting hole 61a is cut off. Therefore, in the second position, the ejection pressure of the pump 100 is guided to the control pressure chamber 23 of the first force application mechanism 20 via the control pressure passage 11 connected to the first connecting hole 61a. As a result, the tilt angle of the inclined plate 8 decreases, and the ejection capacity of the pump 100 decreases.

[0050] On the other hand, in the second position, the first connecting hole 61a and the first control passage 57a are connected via the first control port 56a, and the connection between the second connecting hole 61a and the second connecting hole 61b is cut off. Since the first control passage 57a is connected to the interior of the housing 3 via the axial passage 58a and the connecting passage 73a as described above, in the second position, the fluid tank pressure is guided to the control pressure chamber 23 via the control pressure passage 11. As a result, the tilt angle of the swashplate 8 increases, and the ejection capacity of the pump 100 increases.

[0051] Furthermore, when the position of the control slide valve 52 switches between the first position and the second position, the first connecting hole 61a of the sleeve 60 becomes connected to both the second connecting hole 61b of the sleeve 60 and the first control passage 57a of the control slide valve 52. In other words, the regulator 50 is configured such that when the position of the control slide valve 52 switches between the first position and the second position, the first connecting hole 61a is not connected to any passage, and pressure is not sealed within the first connecting hole 61a and the control pressure chamber 23.

[0052] Next, the operation of the pump 100 with the regulator 50 having the above structure will be explained.

[0053] Pump 100 is controlled by regulator 50 to produce the following characteristics: the relationship between the ejection pressure and the ejection flow rate of pump 100 becomes an approximately inversely proportional rated horsepower characteristic, that is, the product of the ejection pressure and the ejection flow rate becomes an approximately constant characteristic.

[0054] The ejection pressure of pump 100 increases, for example, along with the increase in load of the hydraulic cylinder driven by the ejection pressure of pump 100. When the ejection pressure of pump 100 increases from the state where the tilt angle of swash plate 8 is held at its maximum, the force generated by the ejection pressure of pump 100 acting on control valve 52 is higher than the force generated by the outer spring 51a, and control valve 52 moves from the second position toward the first position.

[0055] When the control slide valve 52 moves to the first position, as described above, the ejection pressure is guided to the control pressure chamber 23 via the control pressure passage 11, and therefore, the pressure in the control pressure chamber 23 rises. Due to the increase in pressure in the control pressure chamber 23, the large-diameter piston 22 is pushed out from the first piston receiving hole 21, and the ramp 8 tilts in the direction where the tilt angle decreases.

[0056] When the inclined plate 8 tilts in the direction where the tilt angle decreases, the feedback pin 40 follows the inclined plate 8 by compressing the outer spring 51a and the inner spring 51b. Figure 1 The swash plate 8 moves to the left. In other words, when the swash plate 8 tilts in the direction where the tilt angle decreases, the feedback pin 40 moves in such a way that the force of the outer spring 51a and the inner spring 51b, which exert force on the control slide valve 52 toward the second position, increases.

[0057] The outer spring 51a and the inner spring 51b increase in force due to compression. When the control valve 52 is pushed back and moved to the second position by the force of the outer spring 51a and the inner spring 51b, the control pressure chamber 23 communicates with the interior of the housing 3 through the control pressure passage 11. Therefore, the pressure in the control pressure chamber 23 gradually decreases.

[0058] When the pressure in the control pressure chamber 23 decreases, the large-diameter piston 22 is pushed back into the first piston receiving hole 21 by the force of the outer spring 51a and the inner spring 51b acting via the inclined plate 8. That is, when the pressure in the control pressure chamber 23 decreases, the inclined plate 8 tilts in the direction of increasing tilt angle, and the force of the outer spring 51a and the inner spring 51b that exert force on the control slide valve 52 decreases. Because the force of the outer spring 51a and the inner spring 51b decreases, the control slide valve 52 moves back to the first position due to the ejection pressure of the pump 100, and the inclined plate 8 tilts again in the direction of decreasing tilt angle.

[0059] The control slide valve 52 repeatedly performs this action and stops at a position where the force acting on the control slide valve 52, generated by the ejection pressure of the pump 100, and the forces of the outer spring 51a and the inner spring 51b are balanced. Additionally, the ramp 8 stops at an angle where the force of the large-diameter piston 22 and the forces of the outer spring 51a and the inner spring 51b are balanced.

[0060] Since the higher the ejection pressure of pump 100, the higher the pressure in the control pressure chamber 23, the higher the ejection pressure of pump 100, the smaller the tilt angle of the ramp 8. As a result, the ejection capacity of pump 100 decreases as the ejection pressure of pump 100 increases.

[0061] On the other hand, when the load on the hydraulic cylinder driven by the ejection pressure of pump 100 decreases, the ejection pressure of pump 100 also decreases accordingly. When the ejection pressure of pump 100 decreases, the force acting on control valve 52 generated by the ejection pressure of pump 100 is lower than the force generated by the outer spring 51a and the inner spring 51b, and control valve 52 moves from the first position to the second position.

[0062] When the control slide valve 52 moves to the second position, as described above, the fluid tank pressure is guided to the control pressure chamber 23 via the control pressure passage 11, thus reducing the pressure within the control pressure chamber 23. As the pressure within the control pressure chamber 23 decreases, the large-diameter piston 22 is pushed back into the first piston receiving hole 21 by the force of the outer spring 51a and the inner spring 51b, which act via the inclined plate 8. As a result, the inclined plate 8 tilts in the direction where the tilt angle increases.

[0063] When the inclined plate 8 tilts in the direction where the tilt angle increases, the feedback pin 40 is subjected to force by the outer spring 51a and the inner spring 51b, especially the outer spring 51a, and follows the inclined plate 8. Figure 1 The swash plate 8 moves to the right. In other words, when the swash plate 8 tilts in the direction where the tilt angle increases, the feedback pin 40 moves in a way that reduces the force of the outer spring 51a and the inner spring 51b that apply force to the control valve 52 toward the second position.

[0064] As the outer spring 51a and inner spring 51b extend, their force decreases. When the force generated by the outer spring 51a and inner spring 51b acting on the control slide valve 52 is lower than the force generated by the ejection pressure of the pump 100, the control slide valve 52 moves from the second position to the first position. When the control slide valve 52 compresses the outer spring 51a and inner spring 51b and moves to the first position, the ejection pressure of the pump 100 is guided to the control pressure chamber 23 via the control pressure passage 11, and therefore, the pressure in the control pressure chamber 23 gradually increases. However, because the ejection pressure of the pump 100 decreases, the degree of pressure increase in the control pressure chamber 23 is smaller compared to the case where the ejection pressure of the pump 100 is higher.

[0065] When the pressure in the control pressure chamber 23 rises, the large-diameter piston 22 is pushed out from the first piston receiving hole 21, causing the inclined plate 8 to tilt in the direction of decreasing tilt angle. As the inclined plate 8 tilts in this direction, the forces exerted on the control slide valve 52 by the outer spring 51a and the inner spring 51b increase. Because the forces of the outer spring 51a and the inner spring 51b increase, the control slide valve 52 moves back to the second position, and the inclined plate 8 tilts again in the direction of increasing tilt angle.

[0066] The control slide valve 52 repeatedly performs this action and stops at a position where the force acting on the control slide valve 52, generated by the ejection pressure of the pump 100, and the forces of the outer spring 51a and the inner spring 51b are balanced. Additionally, the ramp 8 stops at an angle where the force of the large-diameter piston 22 and the forces of the outer spring 51a and the inner spring 51b are balanced.

[0067] Since the lower the ejection pressure of pump 100, the lower the pressure in the control pressure chamber 23, the lower the ejection pressure of pump 100, the larger the tilt angle of the ramp 8. Therefore, the ejection capacity of pump 100 increases as the ejection pressure of pump 100 decreases.

[0068] As described above, the pump 100 is controlled by the regulator 50 in such a way that the pump 100's ejection capacity decreases by increasing the ejection pressure of the pump 100 and the pump 100's ejection capacity increases by decreasing the ejection pressure of the pump 100, that is, in such a way that the relationship between the pump 100's ejection pressure and ejection capacity is approximately inversely proportional.

[0069] In addition to implementing the rated horsepower control described above, the following horsepower reduction control is also implemented: when the engine (drive source) driving the pump 100 drives auxiliary machines such as air conditioners and generators, in order to prevent the generator from stopping due to overload, the driving horsepower of the pump 100 is reduced.

[0070] Next, the power reduction control implemented by regulator 50 will be explained.

[0071] When the auxiliary machine is driven by a generator, signal pressure is supplied to the signal pressure passage 13 from the outside. Specifically, the ejection pressure of a signal pressure generating pump (not shown), which serves as the signal pressure supply source, is guided to the signal pressure passage 13 via a signal pressure control valve (not shown) as the signal pressure. The pressure in the signal pressure passage 13 is controlled by the signal pressure control valve according to the driving state of the auxiliary machine, and is controlled to be a predetermined signal pressure during the period when the auxiliary machine is driven by the engine, and to be equal to the fluid tank pressure during the period when the auxiliary machine is stopped.

[0072] When the auxiliary machine is driven and a predetermined signal pressure is supplied to the signal pressure passage 13 via the signal pressure control valve, the supplied signal pressure is guided to the signal pressure chamber 59b via the third communication hole 61c, the third control port 56c, and the third control passage 57c, as described above. Furthermore, the pressure guided to the signal pressure chamber 59b is the same as the ejection pressure of the pump 100 guided to the ejection pressure chamber 59a, becoming a force that presses the control slide valve 52 in a direction axially away from the plug 70, i.e., in a direction that compresses the outer spring 51a and the inner spring 51b.

[0073] That is, during auxiliary machine operation, in addition to the force generated by the ejection pressure of the pump 100 guided to the ejection pressure chamber 59a, the control slide valve 52 is also subjected to a force generated by the signal pressure guided to the signal pressure chamber 59b, which acts in the direction that moves the control slide valve 52 to the first position. Therefore, the control slide valve 52 operates in the same manner as when the ejection pressure of the pump 100 rises to a predetermined magnitude.

[0074] Therefore, during the auxiliary machine's operation, the ejection capacity of pump 100 is reduced compared to when the auxiliary machine is stopped, i.e., when the pressure in signal pressure chamber 59b is equal to the pressure in the fluid tank. Since the ejection capacity of pump 100 during auxiliary machine operation is reduced in this way, thereby reducing the driving horsepower of pump 100, the engine can, as a result, ensure sufficient horsepower for driving the auxiliary machine.

[0075] Here, when the third port 60c of the guiding signal pressure is set adjacent to the second port 60b of the pump 100 which always guides the injection pressure and the first port 60a of the pump 100 which guides the injection pressure at appropriate times, the relatively high-pressure working oil leaking from the first connection 81, which is the connection between the first port 60a and the control pressure passage 11, and the second connection 82, which is the connection between the second port 60b and the injection pressure passage 10, may reach the third connection 83, which is the connection between the third port 60c and the signal pressure passage 13, and flow into the third port 60c.

[0076] When the relatively high-pressure working oil flows into the third port 60c, the pressure in the signal pressure chamber 59b becomes relatively high. Therefore, even when no signal pressure is supplied to the third port 60c, i.e., even when the auxiliary machine is not driven, the pressure is the same as when signal pressure is supplied to the third port 60c, i.e., when the auxiliary machine is driven. Therefore, the continuous or intermittent supply of control pressure from the regulator 50 to the pump 100 via the control pressure passage 11 results in an unexpected decrease in the injection capacity. As a result, the injection capacity of the pump 100 unexpectedly decreases or fluctuates, and the operation of the hydraulic equipment supplying the working oil may become unstable.

[0077] To avoid the above situation, in this embodiment, the drain passage 63, which communicates with the fluid tank, is opened between the first connection 81 of the first port 60a and the first connection 82 of the control pressure passage 11, the second connection 82 of the second port 60b and the second connection 82 of the ejection pressure passage 10, and the third connection 83 of the third port 60c and the third connection 83 of the signal pressure passage 13. This suppresses the situation where the relatively high-pressure working oil leaking from the first connection 81 and the second connection 82 reaches the third connection 83.

[0078] The following is for reference Figure 2 as well as Figure 3 The drainage passage 63 will be described. Additionally, Figure 3 To be along Figure 2 A magnified cross-sectional view of a portion of the section along line III-III.

[0079] The drainage passage 63 is composed of a fourth port 60d, a fourth connecting hole 61d as a through hole, and a fourth control port 56d. The fourth port 60d is formed as an annular groove on the outer periphery of the sleeve 60. The fourth connecting hole 61d is formed to penetrate the sleeve 60 radially and communicates with the fourth port 60d. The fourth control port 56d is formed as an annular groove on the outer periphery of the main body 53 of the control slide valve 52 and is always in communication with the connecting hole 61d.

[0080] like Figure 2 As shown, the fourth port 60d is configured between the second port 60b and the third port 60c, and the fourth control port 56d is configured between the second control port 56b and the third control port 56c. Thus, one end of the drainage passage 63 is open on the outer peripheral surface of the sleeve 60, and the other end is open on the sliding surface between the sleeve 60 and the control slide valve 52.

[0081] In addition, such as Figure 3 As shown, the fourth connecting hole 61d, which connects the fourth port 60d and the fourth control port 56d, is connected to a recovery passage 62 formed in such a way that it extends axially through the sleeve 60. Figure 3 As shown, in order to avoid the first connecting hole 61a, the second connecting hole 61b, and the third connecting hole 61c which are formed in a radially penetrating manner through the sleeve 60, the recovery passage 62 is provided with a certain degree of interval from the aforementioned connecting holes 61a, 61b, and 61c in the circumferential direction.

[0082] Regarding the direction of forming the fourth connecting hole 61d, it is not limited to the radial direction of the sleeve 60. It can be arbitrarily formed as long as the fourth port 60d and the fourth control port 56d are connected and linked to the recovery passage 62. Furthermore, although the fourth connecting hole 61d and the recovery passage 62 are not formed on the same cross-section of each connecting hole 61a, 61b, 61c and the sleeve 60, Figure 2 In the diagram, the fourth connecting hole 61d and the recycling passage 62 are shown in dashed lines to make it easy to understand their positional relationship with each connecting hole 61a, 61b, and 61c.

[0083] As described above, the recovery passage 62 is open relative to the interior of the housing 3. Therefore, the drainage passage 63 is connected to the interior of the housing 3, which is connected to the fluid tank, via the recovery passage 62. The pressure in the drainage passage 63 is equal to the pressure in the fluid tank.

[0084] Therefore, by opening the drain passage 63, which connects the first port 60a to the first connection 81 of the control pressure passage 11, the second port 60b to the second connection 82 of the ejection pressure passage 10, and the third port 60c to the third connection 83 of the signal pressure passage 13, and connecting to the recovery passage 62, the relatively high-pressure working oil leaking from the first connection 81 and the second connection 82 is guided to the fluid tank via the drain passage 63 and the recovery passage 62 without reaching the third connection 83.

[0085] By preventing the relatively high-pressure working oil leaking from the first connection 81 and the second connection 82 from flowing into the third port 60c, the regulator 50 is prevented from operating as if the signal pressure were supplied when no signal pressure is supplied from the outside. As a result, it is possible to prevent accidental control pressure from being continuously or intermittently supplied to the pump 100 from the regulator 50. Furthermore, since the control pressure supplied to the pump 100 from the regulator 50 is stable, the injection capacity and drive horsepower of the pump 100 are stable, and the operation of the hydraulic equipment supplied with working oil from the pump 100 and the operation of the drive source such as the engine driving the pump 100 are also stable.

[0086] Furthermore, the drainage passage 63 is formed in a radially penetrating manner through the sleeve 60, and also opens on the sliding surface of the sleeve 60 and the control slide valve 52. Therefore, even if high-pressure working oil leaks from the portion where the sleeve 60 and the control slide valve 52 are connected, such as the connection between the second control port 56b and the first connecting hole 61a, or the connection between the second control port 56b and the second connecting hole 61b, the leaked working oil is guided to the fluid tank via the drainage passage 63 (fourth control port 56d, fourth connecting hole 61d) and the recovery passage 62 in a manner that does not reach the connection between the third control port 56c and the third connecting hole 61c.

[0087] By making the drainage passage 63 open on the inner circumferential surface of the first hole 65a of the sleeve 60, the possibility of relatively high-pressure working oil flowing into the signal pressure chamber 59 and the third connecting hole 61c and the third control port 56c is suppressed, not only through the gap between the sleeve 60 and the housing body 3a, but also through the gap between the sleeve 60 and the control slide valve 52. As a result, it is possible to further reliably prevent accidental control pressure from being continuously or intermittently supplied to the pump 100 from the regulator 50.

[0088] Furthermore, the drainage passage 63 communicates with the fluid tank via the recovery passage 62, which is provided in the sleeve 60 to connect the recovery chamber 66 and the interior of the housing 3. Thus, by utilizing a passage pre-formed in the sleeve 60, such as the recovery passage 62, and connecting the drainage passage 63 to the fluid tank, it is unnecessary to separately construct a connecting path between the drainage passage 63 and the fluid tank. Therefore, the increase in manufacturing costs due to adding the drainage passage 63 can be suppressed.

[0089] The above implementation method achieves the following effects.

[0090] In the regulator 50 described above, a drain passage 63, communicating with the fluid tank, is opened between the first connection 81 of the first port 60a and the first connection 81 of the control pressure passage 11, the second connection 82 of the second port 60b and the second connection 82 of the ejection pressure passage 10, and the third connection 83 of the third port 60c and the third connection 83 of the signal pressure passage 13. Therefore, even if high-pressure working oil leaks from the first connection 81 or the second connection 82, the leaked working oil flows into the drain passage 63 without reaching the third connection 83.

[0091] Therefore, when no signal pressure is supplied to the regulator 50 from the outside, the regulator 50 is prevented from operating as if signal pressure were supplied. As a result, it is possible to prevent accidental control pressure from being continuously or intermittently supplied to the pump 100 from the regulator 50. In addition, since the control pressure supplied to the pump 100 from the regulator 50 is stable, the injection capacity and drive horsepower of the pump 100 are stable. As a result, the operation of the hydraulic equipment supplying the working oil and the operation of the drive source such as the engine driving the pump 100 are stable.

[0092] Furthermore, the following modifications are also within the scope of the present invention, and it is possible to combine the structures shown in the modifications with the structures described in the above embodiments, or to combine the structures described in the following different modifications with each other.

[0093] In the above embodiment, the pump 100 supplied with control pressure from the regulator 50 is a swashplate piston pump. The form of the pump 100 is not limited to this; it can be any form, such as a variable-capacity vane pump, as long as it is a pump that changes its capacity by supplying control pressure from the regulator 50 to a mechanism that changes the capacity.

[0094] In addition, in the above embodiment, the drainage passage 63 is provided inside the sleeve 60. Alternatively, the drainage passage may be provided in the housing body 3a. In this case, the drainage passage is formed between the ejection pressure passage 10 and the signal pressure passage 13, with an opening on the inner circumferential surface of the mounting hole 67. In this case, similar to the above embodiment, even if high-pressure working oil leaks from the first connection 81 or the second connection 82, the leaked working oil flows into the drainage passage provided in the housing body 3a without reaching the third connection 83. Furthermore, in order to guide the leaked working oil to the drainage passage, it is preferable to provide an annular groove communicating with the drainage passage on the outer circumferential surface of the sleeve 60 or the inner circumferential surface of the mounting hole 67.

[0095] Furthermore, in the above embodiment, the drainage passage 63 is connected to the recovery passage 62 formed within the sleeve 60. Alternatively, a connecting passage that connects the drainage passage 63 to the fluid tank or the interior of the housing 3 may be separately provided in the housing body 3a. In this case, the connecting passage is formed to open on the inner circumferential surface of the mounting hole 67 formed in the housing body 3a and to communicate with the fourth port 60d.

[0096] Furthermore, in the above embodiment, the signal pressure supplied to the signal pressure passage 13 is either a predetermined signal pressure or a fluid tank pressure. Alternatively, the signal pressure may be a pressure whose magnitude varies stepwise or steplessly between the predetermined signal pressure and the fluid tank pressure. In this case, the ejection capacity of the pump 100 can be varied arbitrarily, and the driving horsepower of the pump 100 can be varied arbitrarily. Since the driving load of the pump 100 can be appropriately changed in this way, for example, the engine driving the pump 100 can be made to rotate and operate under load with better efficiency.

[0097] Furthermore, in the above embodiment, the regulator 50 implements power reduction control, and the signal pressure is supplied only when the auxiliary machine is driven by the engine. Alternatively, for example, it could be that, under normal circumstances, a predetermined signal pressure is supplied to the signal pressure passage 13 to reduce the driving power of the pump 100; however, when there is a margin in the engine output and the required flow rate of working oil in the hydraulic equipment increases, the signal pressure passage 13 is connected to the fluid tank, thereby increasing the injection capacity of the pump 100 and increasing the driving power of the pump 100 compared to normal conditions when predetermined conditions are met. Thus, the regulator 50 could also be used for power increase control instead of power reduction control.

[0098] Furthermore, in the above embodiment, the signal pressure guided to the regulator 50 is the same as the ejection pressure of the pump 100, becoming a force that presses the control slide valve 52 in the direction axially away from the plug 70, i.e., in the direction that compresses the outer spring 51a and the inner spring 51b. Alternatively, as... Figure 4 As shown in the modified example, the signal pressure supplied to the regulator 150 can also be a force that presses the control slide valve 52 in the opposite direction to the ejection pressure of the pump 100.

[0099] exist Figure 4 In the modified example shown, the sleeve 60 has a third hole 65d, which is disposed between the first hole 65a and the second hole 65b, and has a larger inner diameter than the first hole 65a and a smaller inner diameter than the second hole 65b. The control slide valve 52 has a second body part 53a disposed between the body part 53 and the flange part 54 and slidably supported by the third hole 65d.

[0100] Furthermore, in this modified example, the signal pressure liquid chamber 59c for signal pressure guidance is defined by a first hole 65a, a third hole 65d, a connecting surface connecting the first hole 65a and the third hole 65d, a third control port 56c, a first step surface 53b formed by the difference in outer diameter between the third control port 56c and the second main body 53a, and a second step surface 53c formed by the difference in outer diameter between the third control port 56c and the main body 53.

[0101] The signal pressure, guided through the signal pressure passage 13 and the third connecting hole 61c, into the defined signal pressure liquid chamber 59c, acts on the first step surface 53b and the second step surface 53c, which are axially opposed. Here, since the outer diameter of the second main body 53a is larger than the outer diameter of the main body 53, the area of ​​the first step surface 53b formed by the difference in outer diameter between the third control port 56c and the second main body 53a is naturally larger than the area of ​​the second step surface 53c formed by the difference in outer diameter between the third control port 56c and the main body 53.

[0102] Because of the difference in area between the first step surface 53b and the second step surface 53c, the signal pressure guided into the signal pressure chamber 59c operates by pressing the larger area of ​​the first step surface 53b, i.e., by pressing the second main body portion 53a out from the third hole portion 65d. In other words, the control slide valve 52 is pressed in the axial direction towards the plug 70 by the pressure of the working oil guided into the signal pressure chamber 59c, i.e., in the direction that extends the outer spring 51a and the inner spring 51b.

[0103] Thus, in Figure 4In the modified example shown, the signal pressure guided to the signal pressure chamber 59c differs from that in the above embodiment, becoming a force that presses the control slide valve 52 in the direction opposite to the ejection pressure of the pump 100. Therefore, when a predetermined signal pressure is guided to the signal pressure chamber 59c, the control slide valve 52 operates in the same manner as when the ejection pressure of the pump 100 is reduced by a predetermined amount. That is, when the predetermined signal pressure is guided to the signal pressure chamber 59c, the ejection capacity of the pump 100 increases, and the driving horsepower of the pump 100 increases.

[0104] Therefore, in this modified example, similar to the above embodiment, when power reduction control is implemented by regulator 150, the pressure of signal pressure passage 13 is controlled by signal pressure control valve in such a way that it is equal to the fluid tank pressure during the period when the auxiliary machine is driven by the engine, and becomes a signal pressure of a predetermined magnitude during the period when the auxiliary machine is stopped.

[0105] Therefore, during the auxiliary machine's operation, the injection capacity of pump 100 is reduced compared to when the auxiliary machine is stopped. Since the driving horsepower of pump 100 is reduced by decreasing the injection capacity of pump 100 during auxiliary machine operation, the engine can, as a result, ensure sufficient horsepower for driving the auxiliary machine.

[0106] Furthermore, since the drainage passage 63 is also open between the first connection 81 and the second connection 82 and the third connection 83 in this modified example, it suppresses the flow of relatively high-pressure working oil leaking from the first connection 81 and the second connection 82 into the third port 60c. Therefore, it is possible to prevent the unexpected control pressure, such as increasing the injection capacity of the pump 100 from the regulator 150, from being continuously or intermittently supplied. As a result, similar to the embodiment described above, the injection capacity of the pump 100 is stable, and the operation of the hydraulic equipment supplying the working oil is also stable.

[0107] Furthermore, in this modified example, if the signal pressure control valve fails to supply a predetermined amount of signal pressure to the signal pressure passage 13, even if the pressure in the signal pressure passage 13 is equal to the pressure in the fluid tank, the driving horsepower of the pump 100 is reduced. Therefore, it is possible to avoid the situation where the engine load becomes overloaded even if the signal pressure is not supplied due to a malfunction.

[0108] The structure, function, and effects of the embodiments of the present invention are summarized and explained below.

[0109] The regulators 50 and 51 that supply control pressure to the pump 100 include: a housing body 3a having a control pressure passage 11 that guides control pressure to the pump 100, an ejection pressure passage 10 that guides the ejection pressure of the pump 100, a signal pressure passage 13 that guides a signal pressure lower than the ejection pressure used to change the horsepower of the pump 100, and a mounting hole 67 for opening the control pressure passage 11, the ejection pressure passage 10, and the signal pressure passage 13; and a sleeve 60 that is mounted in the mounting hole 67 and has a first port 60a communicating with the control pressure passage 11, a second port 60b communicating with the ejection pressure passage 10, and a second port 60b communicating with the signal pressure passage 13. The third port 60c is connected; the control slide valve 52 is housed in the sleeve 60 in a free sliding manner and is axially displaced according to the ejection pressure supplied via the second port 60b and the signal pressure supplied via the third port 60c, thereby allowing or cutting off the communication between the first port 60a and the second port 60b. A drainage passage 63 communicating with a fluid tank storing working oil is provided on either the housing body 3a or the sleeve 60. The drainage passage 63 opens between the second connection part 82 where the ejection pressure passage 10 is connected to the second port 60b and the third connection part 83 where the signal pressure passage 13 is connected to the third port 60c.

[0110] In this structure, a drain passage 63, communicating with the fluid tank, is opened between the second connection 82 of the second port 60b and the second connection 83 of the injection pressure passage 10, and the third connection 83 of the third port 60c and the third connection 83 of the signal pressure passage 13. Therefore, even if high-pressure working oil leaks from the second connection 82, the leaked working oil flows into the drain passage 63 without reaching the third connection 83. This prevents the regulators 50 and 150 from operating as if signal pressure were supplied when no signal pressure is supplied from the outside. As a result, it prevents accidental control pressure from being continuously or intermittently supplied to the pump 100 from the regulators 50 and 150. Furthermore, because the control pressure supplied to the pump 100 from the regulators 50 and 150 is stable, the injection capacity and drive horsepower of the pump 100 are stable. Consequently, the operation of the hydraulic equipment supplying the working oil and the operation of the drive source such as the engine driving the pump 100 are stable.

[0111] In addition, one end of the drainage passage 63 is open on the outer peripheral surface of the sleeve 60, and the other end is open on the sliding surface between the sleeve 60 and the control slide valve 52.

[0112] In this structure, the drainage passage 63 opens not only on the outer circumferential surface of the sleeve 60, but also on the sliding surface between the sleeve 60 and the control valve 52. This prevents the relatively high-pressure working oil from flowing into the third port 60c not only through the gap between the sleeve 60 and the housing body 3a, but also through the gap between the sleeve 60 and the control valve 52. As a result, it is possible to further reliably prevent accidental control pressure from being continuously or intermittently supplied to the pump 100 from the regulators 50 and 150.

[0113] Additionally, the sleeve 60 is provided with a recovery chamber 66 for recovering the working oil that leaks through the gap between the control slide valve 52 and the sleeve 60, and a recovery passage for recovering the working oil recovered in the recovery chamber 66 to the fluid tank. The drainage passage 63 is connected to the recovery passage 62.

[0114] In this structure, the drain passage 63 is connected to the recovery passage 62, which recovers the working oil leaking through the gap between the control slide valve 52 and the sleeve 60. Thus, by utilizing a passage pre-formed in the sleeve 60, such as the recovery passage 62, and connecting the drain passage 63 to the fluid tank, a separate connection between the drain passage 63 and the fluid tank is eliminated. Therefore, the increase in manufacturing costs due to the installation of the drain passage 63 can be suppressed.

[0115] While the embodiments of the present invention have been described above, these embodiments only illustrate a part of the application examples of the present invention and do not imply that the technical scope of the present invention is limited to the specific structures of the above embodiments.

Claims

1. A pump control pressure regulator that supplies a horsepower control pressure to a pump that controls its drive horsepower according to a horsepower control pressure, characterized in that, have: The housing has a first passage for directing the horsepower control pressure to the pump, a second passage for directing the pump's ejection pressure, a third passage for directing a signal pressure that is lower than the ejection pressure that modifies the pump's horsepower, and a mounting hole for opening the first passage, the second passage, and the third passage. A sleeve is installed in the mounting hole and has a first port communicating with the first passage, a second port communicating with the second passage, and a third port communicating with the third passage; A control slide valve, which is housed in the sleeve in a freely sliding manner, and axially displaces according to the ejection pressure supplied via the second port and the signal pressure supplied via the third port, thereby allowing or cutting off the communication between the first port and the second port. A drainage passage communicating with a fluid tank for storing working fluid is provided on either the outer casing or the sleeve. The drainage passage opens between the second connection portion where the second passage is connected to the second port and the third connection portion where the third passage is connected to the third port.

2. The pump control pressure regulator as described in claim 1, wherein, One end of the drainage passage is open on the outer circumferential surface of the sleeve, and the other end is open on the sliding surface between the sleeve and the control valve.

3. The pump control pressure regulator as described in claim 1 or 2, wherein, The sleeve is provided with a recovery chamber for recovering the working fluid that leaks through the gap between the control slide valve and the sleeve, and a recovery passage for returning the working fluid recovered in the recovery chamber to the fluid tank. The drainage path is connected to the recycling path.

Images