JP2019138223A - Hydraulic pump - Google Patents

Abstract

To provide a hydraulic pump which is stable in an operation while being suppressed in the enlargement of a size.SOLUTION: A hydraulic pump 10 has: a cylinder block 30 which rotates around a rotation axial line A, being the cylinder block 30 in which a plurality of cylinder holes 32 are formed; pistons 38 slidably held in the cylinder holes 32; a swash plate 40 for making the pistons 38 slide in the cylinder holes 32 by the rotation of the cylinder block 30 around the rotation axial line A, being the swash plate 40 whose tilt angle is changeable; first energization means 50 for energizing the swash plate 40 to a direction in which the tilt angle of the swash plate 40 becomes large; and second energization means 60 for energizing the swash plate 40 to a direction in which the tilt angle of the swash plate 40 becomes small. The second energization means 60 has an energization rod 61 for energizing the swash plate 40, and at least either of flow rate control signal pressure and horsepower shift signal pressure acts on an end face 61b at a side opposite to the swash plate 40 at the energization rod 61.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic pump used for construction vehicles and the like, and more particularly to a variable displacement hydraulic pump.

  Variable displacement hydraulic pumps are used in a wide range of fields such as construction vehicles. A variable displacement hydraulic pump generally has a cylinder block that rotates around a rotation axis and has a plurality of cylinder holes extending along the rotation axis direction, and a piston that is slidably held in each cylinder hole. In order to change the inclination angle (tilt angle) of the swash plate with respect to the rotation axis of the cylinder block and the swash plate for sliding each piston in each cylinder hole by rotating the cylinder block around the rotation axis And the mechanism.

  For example, Patent Document 1 discloses a variable displacement swash plate hydraulic pump in which the discharge capacity is adjusted by changing the tilt angle of the swash plate. The hydraulic pump disclosed in Patent Document 1 is configured such that a cylinder block that rotates around a rotation axis, a piston that is slidably held in each cylinder hole formed in the cylinder block, and a tilt angle can be changed. A first urging means for urging the swash plate in a direction in which the tilt angle of the swash plate increases, and a second urging force in a direction in which the tilt angle of the swash plate decreases. The second urging means has an urging rod and a plurality of urging pins, and each urging pin is urged according to a signal pressure corresponding to each urging pin. The swash plate is biased through the rod. According to such a hydraulic pump, there is an advantage that the tilt angle of the swash plate can be adjusted by a simple mechanism.

JP 2018-3609 A

  In the technique disclosed in Patent Document 1, the signal pressure generated by the control valve according to the lever operation of the operator is input to the second pressure chamber formed in the biasing pin unit. The biasing piston is biased by the signal pressure input to the second pressure chamber, and the fourth biasing pin is biased toward the biasing rod by the biasing piston. The inventors of the present invention diligently studied about such a mechanism, and in a hydraulic pump having such a mechanism, a biasing force having a cross-sectional area larger than that of the biasing pin and having a relatively large part size. Since the piston is necessary, it is difficult to downsize the urging pin unit, and it has been found that there is a limit to downsizing and weight reduction of the entire hydraulic pump.

  Further, in the technique disclosed in Patent Document 1, the signal pressure generated by the control valve in response to the lever operation of the operator is changed from the center of the rear end face of the biasing rod to the radial direction via the fourth biasing pin. Acts at a shifted position. As a result, a moment that rotates around an axis perpendicular to the longitudinal direction of the biasing rod can be generated in the biasing rod biased by the signal pressure. Due to this moment, the urging rod is pressed against the first guide part, and a relatively large friction is generated between the urging rod and the first guide part. As a result, the urging rod and the first guide part are worn, and the operation of the urging rod may become unstable. Further, friction is generated between the urging rod and the first guide portion, so that the same signal pressure is input to the second pressure chamber, while moving toward the swash plate side, There is also a possibility that so-called hysteresis is generated in which the position of the biasing rod is different during movement toward the opposite side. This may also cause the operation of the biasing rod to become unstable.

  The present invention has been made in consideration of such points, and an object thereof is to provide a hydraulic pump capable of stable operation while suppressing an increase in size.

The hydraulic pump according to the present invention comprises:
A cylinder block that rotates about a rotation axis, wherein a plurality of cylinder holes are formed;
A piston slidably held in each cylinder hole;
A swash plate for sliding each piston in each cylinder hole by rotating the cylinder block around the rotation axis, and a swash plate configured to change its tilt angle;
First urging means for urging the swash plate in a direction in which the tilt angle of the swash plate is increased;
Second urging means for urging the swash plate in a direction in which the tilt angle of the swash plate decreases,
The second biasing means has a biasing rod that biases the swash plate,
At least one of the flow control signal pressure and the horsepower shift signal pressure acts on the end surface of the biasing rod opposite to the swash plate.

In the hydraulic pump of the present invention,
The flow control signal pressure may act on the end face.

In the hydraulic pump of the present invention,
The flow control signal pressure may be a negative flow control signal pressure.

In the hydraulic pump of the present invention,
The flow control signal pressure or the horsepower shift signal pressure may act on the end face through an orifice.

In the hydraulic pump of the present invention,
The flow control signal pressure or the horsepower shift signal pressure may act on the end face via a slow return mechanism.

In the hydraulic pump of the present invention,
The flow control signal pressure or the horsepower shift signal pressure may be a signal pressure obtained by converting an electric signal into a hydraulic pressure by an electromagnetic proportional valve.

In the hydraulic pump of the present invention,
A signal pressure having a relatively high pressure among the flow control signal pressure and the horsepower shift signal pressure may act on the end face.

In the hydraulic pump of the present invention,
A guide portion for guiding a side surface of the biasing rod;
Pressure oil from another pump may be supplied between the side surface and the guide portion.

In the hydraulic pump of the present invention,
The guide portion is provided with a supply hole for supplying pressure oil from the other pump between the side surface and the guide portion,
The side surface is provided with an oil holding groove for holding pressure oil supplied from the supply hole,
The oil retaining groove may face the supply hole at any position during the forward / backward movement along the guide portion of the biasing rod.

In the hydraulic pump of the present invention,
The second biasing means further includes a biasing pin,
The urging pin may urge the swash plate via the urging rod in accordance with a signal pressure corresponding to the urging pin.

  According to the present invention, it is possible to provide a hydraulic pump capable of stable operation while suppressing an increase in size.

FIG. 1 is a view for explaining an embodiment of the present invention, and is a view showing a cross section of a hydraulic pump. FIG. 2 is a view showing a section of the urging pin unit of the hydraulic pump, and is a view showing a section corresponding to the line II-II in FIG. FIG. 3 is a view showing a modification of the hydraulic pump. FIG. 4 is a view showing another modification of the hydraulic pump. FIG. 5 is a view showing still another modification of the hydraulic pump. FIG. 6 is a view showing still another modification of the hydraulic pump. FIG. 7 is a view showing still another modification of the hydraulic pump. FIG. 8 is a view showing still another modification of the hydraulic pump. FIG. 9 is a view showing still another modified example of the hydraulic pump, and shows a positional relationship between the urging rod and the lubricating oil supply hole when the urging rod is located closest to the swash plate. FIG. FIG. 10 is a diagram showing a positional relationship between the urging rod and the supply hole when the urging rod in FIG. 9 is located closest to the swash plate. FIG. 11 is a cross-sectional view showing still another modification of the hydraulic pump. FIG. 12 is a cross-sectional view showing still another modification of the hydraulic pump.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual ones.

  In addition, as used in the present specification, the shape and geometric conditions and the degree thereof are specified. For example, terms such as “parallel”, “orthogonal”, “identical”, and values of length and angle are strict. Without being bound by meaning, it should be interpreted including the extent to which similar functions can be expected.

  FIGS. 1-11 is a figure for demonstrating one Embodiment by this invention. Among these, FIG. 1 is a figure which shows the cross section of a hydraulic pump.

  The hydraulic pump 10 of the present embodiment is a so-called swash plate type variable displacement hydraulic pump. The hydraulic pump 10 outputs a driving force based on discharge of hydraulic oil from a cylinder hole 32 described later (and supply of hydraulic oil to the cylinder hole 32). More specifically, by rotating the rotating shaft 25 with power from a power source such as an engine, the cylinder block 30 coupled with the rotating shaft 25 by spline coupling or the like is rotated, and the piston is rotated by the rotation of the cylinder block 30. 38 is reciprocated. In response to the reciprocating motion of the piston 38, hydraulic oil is discharged from some of the cylinder holes 32, and hydraulic oil is drawn into the other cylinder holes 32, thereby realizing a hydraulic pump.

  The hydraulic pump 10 shown in FIG. 1 has a housing 20, a rotary shaft 25, a cylinder block 30, a swash plate 40, a first urging means 50 and a second urging means 60. Further, a gear pump 14 as an example of another pump to be described later is attached to the hydraulic pump 10 shown in FIG.

  The housing 20 includes a first housing block 21 and a second housing block 22 coupled to the first housing block 21 by fastening means (not shown). The housing 20 accommodates a part of the rotating shaft 25, the cylinder block 30, the swash plate 40, and the first urging means 50. In the example shown in FIG. 1, inside the first housing block 21, one end of the rotary shaft 25, supply ports and discharge ports (not shown) communicating with the plurality of cylinder holes 32 via the intake / exhaust plate 35 are provided. A first guide part (guide part) 23 for guiding an urging rod 61 described later is disposed. The supply port is provided through the first housing block 21 and communicates with a hydraulic source (tank) provided outside the hydraulic pump 10.

  The first housing block 21 is formed with a rotation shaft hole 24a into which the rotation shaft 25 is inserted. The rotation shaft 25 is rotatably supported around the rotation axis A by a bearing 28a in the rotation shaft hole 24a. . The rotation axis A extends along the longitudinal direction of the rotation shaft 25. One end of the rotary shaft 25 is located in the rotary shaft hole 24a, and is connected to the rotary shaft 16 of the gear pump 14 via a spline coupling portion 26a formed at the one end.

  The second housing block 22 has a rotation shaft hole 24b through which the rotation shaft 25 passes. The rotation shaft 25 extends from one end to the other end through the cylinder block 30 and the swash plate 40. Yes. The rotating shaft 25 is rotatably supported around the rotating axis A by a bearing 28b disposed in the rotating shaft hole 24b at the other end. In the illustrated example, the other end of the rotating shaft 25 protrudes outward from the rotating shaft hole 24b and is connected to a power source such as an engine via a spline coupling portion 26b formed at the other end. The

  In the example shown in FIG. 1, the rotating shaft 25 is spline-coupled to the cylinder block 30 at a spline coupling portion 26 c provided in a portion that penetrates the cylinder block 30. The spline coupling with the cylinder block 30 allows the rotation shaft 25 to move independently of the cylinder block 30 with respect to the direction of the rotation axis A, but rotates together with the cylinder block 30 with respect to the rotation direction around the rotation axis A. To do. The rotary shaft 25 is rotatably supported by a bearing 28a in the first housing block 21 and is rotatably supported by a bearing 28b in the second housing block 22 so as not to contact the swash plate 40. ing. Therefore, the rotation shaft 25 is provided so as to be able to rotate in the rotation direction around the rotation axis A together with the cylinder block 30 without being hindered by members other than the cylinder block 30.

  A gear pump (another pump) 14 is attached to the hydraulic pump 10 of the present embodiment. The gear pump 14 is coupled to the first housing block 21 of the hydraulic pump 10 on the opposite side of the second housing block 22 along the rotation axis A by fastening means (not shown). In the example shown in FIG. 1, the gear pump 14 has a rotating shaft 16. The rotation shaft 16 is disposed so as to be rotatable around the rotation axis A. That is, the rotation shaft 25 and the rotation shaft 16 share the rotation axis A. As described above, one end of the rotating shaft 25 is connected to the rotating shaft 16 of the gear pump 14 via the spline coupling portion 26a formed at the one end. Specifically, one end of the rotation shaft 25 and the sleeve 18 are connected via a spline coupling portion 26a, and the rotation shaft 16 and the sleeve 18 are connected via a spline coupling portion 17a formed on the rotation shaft 16. It is connected.

  When the rotating shaft 25 connected to a power source such as an engine is rotated by a driving force from the power source, the rotating shaft 25 and the rotating shaft 16 rotate integrally around the rotation axis A. As a result, pressure oil is supplied at a constant pressure from the gear pump 14 to each part of the working machine or the like in which the hydraulic pump 10 and the gear pump 14 are incorporated. In particular, in the present embodiment, as will be described later, a part of the pressure oil discharged from the gear pump 14 is supplied between the side surface 61c of the biasing rod 61 and the first guide portion 23 that guides the side surface 61c. Supplied via line L. Since the gear pump 14 can be configured in the same manner as a known gear pump, a description of the specific configuration is omitted.

  The cylinder block 30 rotates around the rotation axis A together with the rotation shaft 25 and has a plurality of cylinder holes 32 drilled around the rotation axis A. In particular, in the example shown in FIG. 1, each cylinder hole 32 is provided so as to extend along a direction parallel to the rotation axis A. The cylinder hole 32 may be provided so as to extend along the direction inclined with respect to the rotation axis A. The number of the plurality of cylinder holes 32 formed in the cylinder block 30 is not particularly limited, but these cylinder holes 32 are equally spaced (equal angular intervals) on the same circumference as viewed from the direction along the rotation axis A. Is preferably arranged.

  Openings 32 a communicating with each of the plurality of cylinder holes 32 are formed at the end of the cylinder block 30 opposite to the side on which the swash plate 40 is provided. Further, an intake / exhaust plate 35 having a plurality of through holes (not shown) is arranged facing the end of the cylinder block 30 opposite to the side where the swash plate 40 is provided. The plurality of cylinder holes 32 communicate with supply ports and discharge ports (not shown) provided in the first housing block 21 through these openings 32a and through holes, and operate through these supply ports and discharge ports. Oil is supplied and discharged. Further, in the example shown in FIG. 1, a spring 44 and retainers 45a and 45b, which will be described later, are accommodated around the rotation shaft 25 at the end of the cylinder block 30 opposite to the side where the swash plate 40 is provided. A recess 30a is formed.

  The suction / exhaust plate 35 shown in FIG. 1 is fixed to the first housing block 21, and even when the cylinder block 30 rotates with the rotary shaft 25, the housing 20 (the first housing block 21). It is stationary. Therefore, the cylinder hole 32 communicating with each of the supply port and the discharge port is switched via the intake / exhaust plate 35 according to the rotation state of the cylinder block 30, and the hydraulic oil is supplied from the supply port to the discharge port. The state of draining oil is repeated.

  The pistons 38 are slidably disposed with respect to the corresponding cylinder holes 32. In other words, the pistons 38 are slidably held in the corresponding cylinder holes 32. In particular, each piston 38 is provided so as to reciprocate along the direction parallel to the rotation axis A with respect to the corresponding cylinder hole 32. The inside of the piston 38 is a cavity and is filled with hydraulic oil in the cylinder hole 32. Therefore, the reciprocating motion of the piston 38 is linked to the supply and discharge of the hydraulic oil to and from the cylinder hole 32. When the piston 38 is pulled out from the cylinder hole 32, the hydraulic oil is supplied from the supply port into the cylinder hole 32, When 38 enters the cylinder hole 32, the hydraulic oil is discharged from the cylinder hole 32 to the discharge port.

  In the present embodiment, a shoe 43 is attached to the end of each piston 38 on the swash plate 40 side (the end on the side protruding from the cylinder hole 32). A spring 44, retainers 45a and 45b, a connecting member 46, a pressing member 47, and a shoe holding member 48 are provided around the rotary shaft 25. The spring 44 and the retainers 45a and 45b are accommodated in a recess 30a formed around the rotary shaft 25 at the end of the cylinder block 30 opposite to the side on which the swash plate 40 is provided. In the example shown in FIG. 1, the spring 44 is a coil spring, and is disposed in a compressed state between the retainer 45a and the retainer 45b in the recess 30a. Therefore, the spring 44 generates a biasing force in the direction in which the spring 44 extends due to its elastic force. The urging force of the spring 44 is transmitted to the pressing member 47 via the retainer 45 b and the connecting member 46. Each shoe 43 is held by the shoe holding member 48, and the pressing member 47 receives the biasing force of the spring 44 and presses each shoe 43 toward the swash plate 40 via the shoe holding member 48.

  In the example shown in FIG. 1, the swash plate 40 can be tilted at various angles. However, the urging force of the spring 44 causes each shoe 43 to move relative to the swash plate 40 regardless of the tilt angle of the swash plate 40. Is properly followed and pressed. As a result, when the piston 38 rotates together with the cylinder block 30, the shoes 43 slide on the swash plate 40 in a circular orbit. In the illustrated example, the end of the piston 38 on the swash plate 40 side forms a spherical convex portion, and the convex portion of the piston 38 is fitted into the spherical concave portion formed in the shoe 43, so that the concave portion of the shoe 43 is The spherical bearing structure is formed by the piston 38 and the shoe 43. With this spherical bearing structure, even if the tilt angle of the swash plate 40 changes, each shoe 43 can appropriately slide and rotate on the swash plate 40 following the tilt of the swash plate 40.

  The swash plate 40 is for sliding the pistons 38 in the cylinder holes 32 as the cylinder block 30 rotates around the rotation axis A. The swash plate 40 has a flat sliding surface 41 on the side facing the cylinder block 30, and a shoe 43 connected to the end of the piston 38 on the swash plate 40 side is pressed against the sliding surface 41. Yes. Further, the swash plate 40 is provided so as to be tiltable, and the stroke of the reciprocating motion of the piston 38 changes according to the tilt angle of the swash plate 40 (sliding surface 41). That is, the larger the tilt angle of the swash plate 40 (sliding surface 41), the larger the amount of hydraulic oil supplied to and discharged from the cylinder hole 32 that accompanies the reciprocating motion of each piston 38. The smaller the tilt angle, the smaller the amount of hydraulic oil supplied to and discharged from the cylinder hole 32 that accompanies each piston 38 reciprocatingly. Here, the tilt angle of the swash plate 40 (sliding surface 41) means an angle formed by the plate surface (sliding surface 41) of the swash plate 40 with respect to a virtual plane orthogonal to the rotation axis A. Yes. When the tilt angle is 0 degree, each piston 38 does not reciprocate even if the cylinder block 30 rotates around the rotation axis A, and the amount of hydraulic oil discharged from each cylinder hole 32 becomes zero. In the example shown in FIG. 1, the swash plate 40 comes into contact with a stopper 27 provided on the second housing block 22 as the tilt angle is reduced. The stopper 27 is configured to be movable back and forth with respect to the swash plate 40. Thus, the minimum tilt angle of the swash plate 40 can be adjusted as appropriate by moving the stopper 27 forward and backward with respect to the swash plate 40. Further, the swash plate 40 has an abutting surface 42 on the outside of the sliding surface 41, to which an urging rod 61 described later abuts and receives an urging force from the urging rod 61. In the illustrated example, the contact surface 42 is provided so as to be parallel to the sliding surface 41.

  The first urging means 50 urges the swash plate 40 in a direction in which the tilt angle of the swash plate 40 increases. In the example shown in FIG. 1, the first urging means 50 includes a first retainer 51 disposed on the side opposite to the swash plate 40 (first housing block 21 side) and the swash plate 40 side (second housing block). 22) and a spring 54, 55 disposed between the first retainer 51 and the second retainer 52. The first spring 54 is disposed in a compressed state between the first retainer 51 and the second retainer 52. Therefore, the first spring 54 generates a biasing force in the direction in which the first spring 54 extends due to its elastic force. The second spring 55 is disposed inside the first spring 54. For this reason, the winding diameter of the second spring 55 is formed smaller than the winding diameter of the first spring 54.

  In the example shown in FIG. 1, the second spring 55 is fixed to the second retainer 52 and is separated from the first retainer 51 in a state where the tilt angle of the swash plate 40 is large (see FIG. 1). Thus, only the urging force of the first spring 54 acts on the swash plate 40 while the tilt angle of the swash plate 40 is large. As the tilt angle of the swash plate 40 decreases, the second spring 55 contacts the first retainer 51 at a certain tilt angle. When the tilt angle of the swash plate 40 is further reduced, the second spring 55 is also compressed between the first retainer 51 and the second retainer 52, whereby the first spring 54 and the second spring are applied to the swash plate 40. Both urging forces of 55 act. Therefore, according to the illustrated first urging means 50, the urging force can be changed stepwise according to the tilt angle of the swash plate 40. The second spring 55 is not limited to the one that is fixed to the second retainer 52, and may be fixed to the first retainer 51, or may be fixed to both the first retainer 51 and the second retainer 52. Instead, it may be movable between the first retainer 51 and the second retainer 52. In the illustrated example, the separation distance of the first retainer 51 from the second retainer 52 can be adjusted by moving the adjuster 57 forward and backward toward the first retainer 51. Thereby, the initial urging force of the first urging means 50, in particular, the initial urging force of the first urging means 50 by the first spring 54 can be appropriately adjusted.

  The second urging means 60 causes the swash plate 40 to apply a biasing force in a direction opposite to the biasing force applied to the swash plate 40 by the first biasing means 50. In particular, the second urging means 60 is inclined in the direction in which the inclination angle of the swash plate 40 is decreased against the urging force of the first urging means 50 in the direction in which the inclination angle of the swash plate 40 is increased. The plate 40 is energized. In the example shown in FIG. 1, the second biasing means 60 includes a biasing rod 61 and a biasing pin unit 70. The biasing rod 61 is biased toward the swash plate 40 by the signal pressure P input (introduced) into the first pressure chamber 81 formed between the biasing rod 61 and the biasing pin unit 70. The swash plate 40 is tilted around its tilt axis. The urging pin unit 70 includes a unit case 76 and a plurality of first urging pins 71. Each first urging pin 71 urges the urging rod 61 toward the swash plate 40 in accordance with the signal pressure corresponding to each first urging pin 71. In other words, each first biasing pin 71 biases the swash plate 40 via the biasing rod 61 according to the signal pressure corresponding to each first biasing pin 71.

  In the example shown in FIG. 1, the urging rod 61 has a substantially cylindrical shape as a whole, and is attached to the contact surface 42 of the swash plate 40 so that its axis is parallel to the rotation axis A. The biasing pin unit 70 is disposed between each first biasing pin 71. The urging rod 61 is not limited to one whose axis is arranged in parallel to the rotation axis A, and may be one in which the axis is inclined with respect to the rotation axis A. The urging rod 61 includes a front end surface 61a that faces the swash plate 40 (contact surface 42), a rear end surface (end surface) 61b that is opposite to the front end surface 61a along the axis of the urging rod 61, and a front end surface. It has a side surface 61c that connects 61a and the rear end surface 61b. In the illustrated example, the tip surface 61a has a spherical shape. Thus, even if the angle formed between the swash plate 40 (contact surface 42) and the urging rod 61 changes due to the change in the tilt angle of the swash plate 40, the urging force against the swash plate 40 is applied to the tip surface 61a. To the contact surface 42. Further, the rear end surface 61 b of the urging rod 61 has a flat surface orthogonal to the axis of the urging rod 61. The rear end surface 61b only needs to have a shape that can function as an action surface on which the signal pressure P acts, and the specific shape is not particularly limited. The rear end surface 61b may have a flat surface inclined with respect to the axis of the urging rod 61 or may include a curved surface. For example, the rear end surface 61b has a spherical shape protruding from the urging rod 61, a spherical shape recessed toward the urging rod 61, a wave shape, a shape combining a plurality of flat surfaces, a shape combining a plurality of curved surfaces, and a flat surface. The shape which combined the curved surface and the shape containing a step part, etc. may be sufficient.

  The first housing block 21 (housing 20) is provided with a first guide part (guide part) 23 for guiding the side surface 61c of the urging rod 61. The urging rod 61 is provided with the first guide part 23. It is slidably arranged with respect to. For this reason, a part of the urging rod 61 is slidably held in the first guide portion 23. The first guide portion 23 is configured by a through hole provided in the first housing block 21 and has a cross-sectional shape that is complementary to the cross-sectional shape of the biasing rod 61. That is, the 1st guide part 23 is comprised by the cylindrical through-hole with a circular cross section. In the example shown in FIG. 1, the first guide portion 23 is provided integrally with the first housing block 21 (housing 20). When the first guide portion 23 is provided integrally with the first housing block 21, the first guide portion 23 can be formed by drilling the first housing block 21, and the first guide portion 23 can be formed by simple processing. 23 can be formed. Further, since no additional member is required to provide the first guide portion 23, the number of parts of the hydraulic pump 10 and the cost can be reduced. In addition, the structure of the 1st guide part 23 is not restricted to this. As an example, a first guide portion 23 formed using a member different from the first housing block 21, for example, in a cylindrical shape, may be attached to the housing 20.

  The first housing block 21 (housing 20) is formed with a concave portion 29 communicating with the first guide portion 23, and the convex portion 78 of the urging pin unit 70 is fitted into the concave portion 29.

  When the swash plate 40 is urged by the urging rod 61, a force in a direction inclined with respect to the axial direction of the urging rod 61 may act on the urging rod 61 due to a reaction force from the swash plate 40. . Since the hydraulic pump 10 of the present embodiment has the first guide portion 23 described above, a force in a direction inclined with respect to the axial direction of the urging rod 61 acts on the urging rod 61. Since the 1st guide part 23 can hold | maintain the biasing rod 61 appropriately, the biasing rod 61 can be operated stably.

  In the example shown in FIG. 1, pressure oil from another pump is supplied between the side surface 61 c of the urging rod 61 and the first guide portion 23. In the illustrated example, a gear pump 14 attached to the hydraulic pump 10 is used as another pump. Pressure oil is supplied from the gear pump 14 through the supply line L into the first guide portion 23. As an example, the supply line L may be a passage that opens through the gear pump 14 and the inside of the housing 20 (first housing block 21) to the first guide portion 23. The other pump may be a hydraulic pump arranged independently of the hydraulic pump 10, or may be a hydraulic pump other than the gear pump.

  The pressure oil supplied from the other pump functions as a lubricating oil that reduces the frictional resistance between the side surface 61 c and the first guide portion 23. In the technique disclosed in Patent Document 1, oil held in the housing or in the recess of the first housing block is supplied to the side surface of the urging rod, whereby the side surface of the urging rod and the first guide portion are During the lubrication. In the present embodiment, the pressure oil discharged from another pump is forcibly supplied between the side surface 61c and the first guide portion 23 at a predetermined pressure, so that the side surface 61c and the first guide are more effectively supplied. Lubrication with the part 23 can be performed. In particular, in the technique disclosed in Patent Document 1, when the urging rod starts to move, even if the urging force by the urging pin starts to be generated, the urging rod does not move, and the urging force by the urging pin becomes large. Suddenly, the energizing rod sometimes started moving. As a result, the tilt angle of the swash plate changes abruptly, and there is a risk that the hydraulic oil cannot be stably discharged by the hydraulic pump. On the other hand, in the present embodiment, the urging rod 61 is supplied by forcibly supplying the pressure oil discharged from another pump between the side surface 61c and the first guide portion 23 at a predetermined pressure. Can be moved smoothly, and the hydraulic oil can be stably discharged by the hydraulic pump 10.

  In the technique disclosed in Patent Document 1, the urging force of each urging pin acts at a position shifted in the radial direction from the center of the rear end surface of the urging rod. As a result, a moment that rotates around an axis perpendicular to the longitudinal direction of the biasing rod can be generated in the biasing rod biased by the biasing force. Due to this moment, the urging rod is pressed against the first guide part, and a relatively large friction is generated between the urging rod and the first guide part. Accordingly, the urging rod is moved during the movement toward the swash plate side and during the movement toward the opposite side of the swash plate even though the same signal pressure is input to the first pressure chamber and the second pressure chamber. There is also a possibility that so-called hysteresis occurs at different positions. On the other hand, in the present embodiment, the urging rod 61 is supplied by forcibly supplying the pressure oil discharged from another pump between the side surface 61c and the first guide portion 23 at a predetermined pressure. Friction that may occur between the side surface 61c of the first guide portion 23 and the first guide portion 23 can be reduced, and the occurrence of hysteresis with respect to the position of the biasing rod 61 can be suppressed.

  An oil holding groove 65 for holding pressure oil supplied from another pump is provided on the side surface 61c of the urging rod 61. In the example shown in FIG. 1, the oil retaining groove 65 has a predetermined width in the longitudinal direction (axial direction) of the biasing rod 61, a predetermined depth in the radial direction, and along the side surface 61c. It is formed over the entire circumference in the circumferential direction. In other words, the urging rod 61 has a small diameter portion with a relatively small diameter and a diameter larger than the diameter of the small diameter portion adjacent to the distal end side (the distal end surface 61a side) of the small diameter portion along the longitudinal direction. A first large-diameter portion having a second large-diameter portion adjacent to the rear end side (rear end surface 61b side) of the small-diameter portion along the longitudinal direction and having a diameter larger than the diameter of the small-diameter portion. Yes. In the illustrated example, the diameter of the first large diameter portion and the diameter of the second large diameter portion are the same. The depth along the radial direction of the oil retaining groove 65 can be set to 0.5 mm or more and 1.5 mm or less as an example. Since the urging rod 61 has such an oil retaining groove 65, a cylindrical gap is formed between the urging rod 61 and the first guide portion 23, and this gap is formed from another pump. It becomes possible to hold the supplied pressure oil. Accordingly, the lubricating oil is stably and uniformly supplied from the oil holding groove 65 between the first large diameter portion and the first guide portion 23 and between the second large diameter portion and the first guide portion 23. Can be supplied. Therefore, the urging rod 61 can be operated stably and smoothly. The specific shape of the oil retaining groove 65 is not limited to the shape shown in FIG.

  The surface of the urging rod 61 may be subjected to a surface treatment in order to suppress wear of the urging rod 61 and the like. When the front end surface 61a of the urging rod 61 is subjected to surface treatment, the frictional resistance between the front end surface 61a and the contact surface 42 of the swash plate 40 is reduced, and the front end surface 61a and the contact surface 42 are worn. Can be suppressed. When the surface treatment is applied to the side surface 61c of the urging rod 61, the frictional resistance between the side surface 61c and the first guide portion 23 can be reduced, and wear of the side surface 61c and the first guide portion 23 can be suppressed. . Further, when the rear end surface 61b of the urging rod 61 is subjected to surface treatment, wear of the rear end surface 61b and the first urging pin 71 and the adjustment pin 73 that are in contact with the rear end surface 61b can be suppressed. Such a surface treatment can be performed, for example, by forming an amorphous carbon film on the surface of the urging rod 61.

  A first pressure chamber 81 is formed between the urging rod 61 and the urging pin unit 70. More specifically, a space located between the rear end surface 61 b of the urging rod 61 and the urging pin unit 70 is the first pressure chamber 81. A signal pressure P that is at least one of a flow control signal pressure and a horsepower shift signal pressure is input to the first pressure chamber 81. Thereby, the signal pressure P acts on the rear end surface 61b of the urging rod 61. In particular, the signal pressure P acts directly on the rear end surface 61 b of the urging rod 61. Here, “acting directly” means that the signal pressure P acts on the rear end surface 61b of the biasing rod 61 without passing through another member such as a biasing pin.

  The flow control signal pressure is a signal pressure generated in response to a lever operation by an operator who operates a work machine in which the hydraulic pump 10 is incorporated. More specifically, the flow control signal pressure is a signal pressure generated in response to the operation of the control valve in accordance with the lever operation by the operator. For example, in a negative flow rate control (negative control) mechanism, an orifice is provided between a control valve and a tank in a center bypass line from a variable displacement hydraulic pump to a tank via a control valve. The leak flow rate of the pressure oil passing through the orifice is detected as the back pressure of the orifice, and the detected back pressure is fed back to the variable displacement hydraulic pump as a negative flow control signal pressure. As an example, this negative flow control signal pressure can be input to the first pressure chamber 81 as a flow control signal pressure.

  Further, a load sensing (LS) flow control signal pressure can be used as the flow control signal pressure. When the flow reduction signal pressure from the load sensing flow control mechanism is input into the first pressure chamber 81, the urging rod 61 is urged toward the swash plate 40, and the tilt angle of the swash plate 40 is reduced. . Thereby, the amount of pressure oil discharged from the hydraulic pump 10 decreases.

  The horsepower shift signal pressure is a signal pressure for reducing (shifting) the maximum discharge flow rate of the pressure oil from the hydraulic pump 10. For example, when using a working machine or the like in which the hydraulic pump 10 is incorporated at a high altitude, the amount of oxygen contained in the atmosphere is small, and thus the driving force output from a power source such as an engine is reduced. In this state, if the tilt angle of the swash plate 40 is maximized so that the hydraulic oil is discharged from the hydraulic pump 10 at the maximum discharge flow rate, a high load may be applied to the power source, and the power source may stall. In order to prevent this, the horsepower shift signal pressure is inputted to the first pressure chamber 81 at a high altitude to shift the maximum tilt angle of the swash plate 40 small, and the maximum discharge of the pressure oil from the hydraulic pump 10. The flow rate can be reduced.

  Only one of the flow control signal pressure and the horsepower shift signal pressure may be input to the first pressure chamber 81, or both the flow control signal pressure and the horsepower shift signal pressure are input to the first pressure chamber 81. Also good.

  As described above, by causing at least one of the flow control signal pressure and the horsepower shift signal pressure to act on the rear end surface 61b of the biasing rod 61, the component size is relatively large in the technique disclosed in Patent Document 1. Therefore, the enlargement of the hydraulic pump 10 can be effectively suppressed.

  Further, as described above, in the technique disclosed in Patent Document 1, the signal pressure generated by the control valve in response to the operator's lever operation is applied to the rear end surface of the urging rod via the fourth urging pin. It acts on the position shifted from the center in the radial direction. As a result, a moment that rotates around an axis perpendicular to the longitudinal direction of the biasing rod can be generated in the biasing rod biased by the signal pressure. Due to this moment, the urging rod is pressed against the first guide part, and a relatively large friction is generated between the urging rod and the first guide part. As a result, the urging rod and the first guide part are worn, and the operation of the urging rod may become unstable. Further, friction is generated between the urging rod and the first guide portion, so that the same signal pressure is input to the second pressure chamber, while moving toward the swash plate side, There is also a possibility that so-called hysteresis is generated in which the position of the biasing rod is different during movement toward the opposite side. This may also cause the operation of the biasing rod to become unstable. On the other hand, in the present embodiment, at least one of the flow control signal pressure and the horsepower shift signal pressure acts on the entire rear end surface 61b of the biasing rod 61, and is orthogonal to the longitudinal direction of the biasing rod. It is possible to effectively suppress the generation of a moment that rotates around the axis line. Therefore, the wear of the urging rod 61 and the first guide portion 23 and the occurrence of hysteresis with respect to the position of the urging rod 61 can be suppressed. That is, it becomes possible to give stability to the operation of the hydraulic pump 10.

  Note that the area of the rear end surface 61 b of the urging rod 61 is sufficiently larger than the cross-sectional area of the first urging pin 71, so even when a relatively small signal pressure is input to the first pressure chamber 81. The urging rod 61 can exert a sufficient urging force to change the tilt angle of the swash plate 40 without using the urging piston.

  Next, a specific configuration of the urging pin unit 70 will be described with reference to FIGS. 1 and 2. FIG. 2 shows a cross section corresponding to the line II-II in FIG. In the illustrated example, the urging pin unit 70 includes a plurality of first urging pins 71, an adjustment pin 73, an adjuster 77, and a unit case 76. Each first urging pin 71 urges the swash plate 40 via the urging rod 61 according to the signal pressure corresponding to each first urging pin 71.

  In the example shown in FIGS. 1 and 2, the first urging pin 71 has a substantially cylindrical shape as a whole, and the urging force is such that its axis is parallel to the axis of the urging rod 61. The rod 61 is disposed on the opposite side of the swash plate 40. In particular, in the illustrated example, the first urging pin 71 is disposed such that its axis is parallel to the rotation axis A. The front end surface of the first urging pin 71 facing the urging rod 61 has a flat surface. In addition, it is not restricted to this, The front end surface of the 1st urging | biasing pin 71 may have shapes other than flat surfaces, such as spherical shape.

  The unit case 76 is provided with a plurality of second guide portions 75 for guiding the side surfaces of the first urging pins 71, and each of the first urging pins 71 is arranged with respect to each second guide portion 75. It is slidably arranged. Therefore, each first urging pin 71 is slidably held in the second guide portion 75 corresponding to at least a part thereof. Each second guide portion 75 is configured by a hole provided in the unit case 76 and has a cross-sectional shape that is complementary to the cross-sectional shape of the first biasing pin 71. That is, each second guide portion 75 is configured by a cylindrical hole having a circular cross section. A second pressure chamber 82 that receives a signal pressure applied to the first biasing pin 71 is formed on the opposite side of the first biasing pin 71 to the biasing rod 61 in the second guide portion 75.

  In the example shown in FIGS. 1 and 2, the second guide portion 75 is provided integrally with the unit case 76. When the second guide portions 75 are provided integrally with the unit case 76, each second guide portion 75 can be formed by drilling the unit case 76, and the second guide portions 75 can be formed by simple processing. It becomes possible to do. Further, since no additional member is required to provide the second guide portion 75, the number of parts of the hydraulic pump 10 and the cost can be reduced. In addition, the structure of the 2nd guide part 75 is not restricted to this. As an example, a second guide portion 75 that is formed using a member that is different from the unit case 76, for example, a cylindrical shape, may be attached to the unit case 76.

  The adjustment pin 73 is a member for adjusting the position of the urging rod 61 when the urging rod 61 is pushed most into the opposite side of the swash plate 40. Therefore, the position of the adjustment pin 73 in the longitudinal direction can be adjusted by the adjuster 77. In the example shown in FIG. 1, the adjuster 77 includes a set screw and a nut. The unit case 76 has a through hole that connects a surface of the unit case 76 opposite to the urging rod 61 and a rear chamber 89 in which an end of the adjustment pin 73 opposite to the urging rod 61 is accommodated. The set screw of the adjuster 77 is screwed into the through hole. Therefore, the position of the adjustment pin 73 in the longitudinal direction can be adjusted by rotating the set screw to change the position of the set screw with respect to the through hole.

  On the housing 20 side (the urging rod 61 side) of the unit case 76, there is a convex portion 78 formed so as to surround the first urging pin 71. The convex portion 78 is fitted into a concave portion 29 provided in the first housing block 21 (housing 20). As shown in FIG. 2, the convex part 78 has a circular cross section. Further, the concave portion 29 of the first housing block 21 also has a circular cross-sectional shape corresponding to the cross-sectional shape of the convex portion 78.

  If the first urging pin 71 is configured to be able to urge the urging rod 61 toward the swash plate 40 in accordance with the signal pressure corresponding to each first urging pin 71, its specific shape and Although arrangement | positioning is not specifically limited, As an example, each 1st urging | biasing pin 71 can be made into the shape and arrangement | positioning which are mainly demonstrated below with reference to FIG.

  In the example shown in FIG. 2, each first urging pin 71 and adjustment pin 73 are viewed from the axial direction of each first urging pin 71 and adjustment pin 73, that is, viewed from the axial direction of the urging rod 61. All of them have a circular cross section having the same diameter. According to the first urging pins 71 and the adjustment pins 73 having such shapes, for example, the first urging pins 71 and the adjustment pins 73 are manufactured by cutting one elongated bar. Can do. Moreover, it can form by drilling the 2nd guide part 75 with the same diameter. Thereby, the manufacturing process of each 1st urging | biasing pin 71, the adjustment pin 73, and each 2nd guide part 75 can be simplified.

  Further, in the illustrated example, each first urging pin 71 is disposed such that its center (axis) is located on one circumference C when viewed from the axial direction of each first urging pin 71. ing. In particular, the first urging pins 71 are arranged at equal intervals along one circumference C. In other words, the central angles at the center of the circumference C by the two first urging pins 71 adjacent on the circumference C are all equal. In the illustrated example, the central angles at the center of the circumference C by the two first urging pins 71 adjacent on the circumference C are all 90 °. Further, in the illustrated example, the center (axis line) of each first urging pin 71 is disposed in a region overlapping with the urging rod 61 when viewed from the axial direction of each first urging pin 71. Further, in the illustrated example, the entire first urging pin 71 is disposed in a region overlapping the urging rod 61 as viewed from the axial direction of each first urging pin 71. By arranging the first urging pin 71 in this way, the urging pin unit 70 can be effectively downsized.

  In the example shown in FIGS. 1 and 2, the urging rod 61, each first urging pin 71, and the adjustment pin 73 are formed of solid members. When the urging rod 61 and the pins 71 and 73 are formed of a solid member, the urging rod 61 and the pins 71 and 73 can be manufactured by a relatively simple process, and the urging rod 61 and the pin 71 are also manufactured. , 73 can be provided with sufficient mechanical strength. Therefore, it is possible to effectively prevent deformation of the urging rod 61 and the pins 71 and 73 while reducing the size of the urging rod 61 and the pins 71 and 73, and thereby the tilting operation of the swash plate 40 is extremely reduced. It can be performed stably.

  Note that a groove or notch through which oil can flow may be provided on the side surface of the adjustment pin 73 from one end to the other end. As an example, the cutout may have a part of the side surface chamfered so that the cross section perpendicular to the longitudinal direction of the adjustment pin 73 is substantially D-shaped. For example, if oil flows into the rear chamber 89 from the first pressure chamber 81 through the gap between the adjustment pin 73 and the unit case 76, the position of the adjustment pin 73 may shift to the biasing rod 61 side due to the presence of this oil. There is. On the other hand, when a groove or a notch is provided on the side surface of the adjustment pin 73, when the adjustment pin 73 is pressed by the urging rod 61, the oil flowing into the rear chamber 89 is removed from the groove or the notch. Can be quickly returned to the first pressure chamber 81. Therefore, it is possible to improve the positional accuracy of the urging rod 61 when the urging rod 61 is pushed most into the opposite side of the swash plate 40.

  In each second pressure chamber 82 corresponding to each first urging pin 71, for example, a signal pressure due to hydraulic oil discharged from the hydraulic pump 10 or a signal from another hydraulic pump driven by the same drive source is provided. Pressure, signal pressure corresponding to the operation of an external device such as an air conditioner driven by the same drive source, and the like are input. When the hydraulic pump 10 is a so-called split flow structure hydraulic pump having the function of two pumps with one pump, the signal pressures of the two hydraulic oils discharged from the hydraulic pump 10 are different from each other. Input to the force pin 71 is possible.

  Accordingly, each first urging pin 71 is driven by the signal pressure from the hydraulic oil discharged from the hydraulic pump 10, the signal pressure from another hydraulic pump driven by the same drive source, or the same drive source. It is driven by signal pressure corresponding to the operation of external equipment such as air conditioners. Accordingly, each first urging pin 71 urges the urging rod 61 toward the swash plate 40.

  Next, the tilting operation of the swash plate 40 will be described. The rotary shaft 25 of the hydraulic pump 10 is driven by a drive source such as a diesel engine. When a load larger than the driving force of the driving source is applied to the driving source, the driving source stalls. Therefore, it is necessary to control the operation of the hydraulic pump 10 so that the load on the drive source is less than or equal to the drive force of the drive source. In hydraulic equipment, a plurality of hydraulic pumps may be driven by a single drive source. In this case, it is preferable to control the operation of the hydraulic pump 10 so that the total driving force of the plurality of hydraulic pumps driven by one driving source is equal to or less than the driving force of the driving source. Furthermore, when an external device such as an air conditioner is driven by the same drive source, it is preferable to control the operation of the hydraulic pump 10 in consideration of a load on the drive source by the external device.

  Further, when the operator operating the hydraulic equipment does not operate the operation lever, the hydraulic actuator driven by the hydraulic oil discharged from the hydraulic pump does not operate. Further, when the operator operates the operation lever at a shallow angle (fine operation), the hydraulic actuator operates slowly (fine operation). In these cases, the hydraulic actuator requires only a small amount of hydraulic oil from the hydraulic pump, and hydraulic oil that has not been used to drive the hydraulic actuator has been conventionally discharged to a recovery tank or the like. However, in this case, most of the driving force of the hydraulic pump is wasted, and the fuel consumed by a driving source such as a diesel engine that drives the hydraulic pump is also wasted. Conventionally, some so-called high-grade hydraulic devices have a function of reducing the amount of hydraulic oil discharged from the hydraulic pump when the hydraulic actuator is not operating and when the hydraulic actuator is not operating. However, inexpensive hydraulic equipment having such a function has not been realized. Therefore, it is desired to realize a function of reducing the hydraulic oil discharge amount of the hydraulic pump when the hydraulic actuator is not operating and finely operating with a simple mechanism.

  Here, the negative flow rate control signal pressure is input to the first pressure chamber 81, and the signal pressure by the hydraulic oil discharged from the hydraulic pump 10 to the second pressure chamber 82 corresponding to each first urging pin 71 is the same. An example in which a signal pressure from another hydraulic pump driven by this drive source and a signal pressure corresponding to the operation of an air conditioner driven by the same drive source are input will be described.

  Note that the first biasing pin 71 corresponding to the second pressure chamber 82 to which no signal pressure is input can be a preliminary biasing pin. When such a reserve urging pin is provided, when another hydraulic pump or external device is added and the hydraulic pump 10 is to be controlled in consideration of the operation of the hydraulic pump or external device, the hydraulic pump Or by inputting the signal pressure from the external device to the second pressure chamber 82 corresponding to the auxiliary urging pin, the auxiliary urging pin can be used as the urging pin corresponding to the hydraulic pump or the external device. can do. Therefore, it is possible to flexibly cope with the addition of other hydraulic pumps and external devices, and the versatility of the hydraulic pump 10 can be effectively improved.

  The swash plate 40 is urged by the first urging means 50 in a direction that increases the tilt angle of the swash plate 40, and the second urging means 60 is applied in a direction that decreases the tilt angle of the swash plate 40. Be forced. The swash plate 40 has a magnitude of the moment around the tilting axis of the swash plate 40 (counterclockwise moment in FIG. 1) by the urging force of the first urging means 50 and the swash plate 40 by the second urging means 60. Tilt to a position where the magnitude of the moment around the tilt axis (clockwise moment in FIG. 1) is equal, and stops.

  In the example described here, the flow rate control signal pressure is input to the first pressure chamber 81. Specifically, the back pressure of the orifice in the center bypass line of the negative flow control mechanism is detected, and this detected back pressure is input to the first pressure chamber 81 as a negative flow control signal pressure. The flow rate control signal pressure input to the first pressure chamber 81 acts on the rear end surface 61 b of the urging rod 61. In particular, the flow control signal pressure input to the first pressure chamber 81 presses the rear end surface 61 b of the urging rod 61.

  In order to cause the hydraulic actuator to be inoperative or finely operated, if the flow rate of the pressure oil directed to the hydraulic actuator via the control valve is decreased by operating the control valve in the negative flow control mechanism, the control valve is controlled from the hydraulic pump 10. The flow rate of the pressure oil that is returned to the tank via the center bypass line is increased. An orifice is provided between the control valve and the tank in the center bypass line. When the flow rate of pressure oil through the center bypass line increases, the pressure of the pressure oil (back pressure) before the orifice in the center bypass line is increased. Increase. By inputting this back pressure into the first pressure chamber 81 as a negative flow control signal pressure, this signal pressure acts on the rear end surface 61b of the urging rod 61, and the urging rod 61 is moved to the swash plate 40 (contact surface 42). ).

  A signal pressure due to the hydraulic oil discharged from the hydraulic pump 10 is input to the second pressure chamber 82 corresponding to one first urging pin 71 of the plurality of first urging pins 71. For example, the flow path of the hydraulic oil discharged from the hydraulic pump 10 is branched and connected to the second pressure chamber 82, so that the signal pressure due to the hydraulic oil discharged from the hydraulic pump 10 is applied to the first biasing pin 71. Input to the corresponding second pressure chamber 82. When the load of the hydraulic actuator driven by the hydraulic oil discharged from the hydraulic pump 10 increases, the pressure of the hydraulic oil discharged from the hydraulic pump 10 increases. That is, the signal pressure due to the hydraulic oil discharged from the hydraulic pump 10 increases. The first urging pin 71 is urged toward the urging rod 61 by this signal pressure. Accordingly, the first urging pin 71 urges the swash plate 40 (contact surface 42) via the urging rod 61.

  Signal pressures from other hydraulic pumps driven by the same drive source are input to the second pressure chambers 82 corresponding to the other first urging pins 71. For example, the flow path of the hydraulic oil discharged from another hydraulic pump is branched and connected to the second pressure chamber 82, so that the signal pressure due to the hydraulic oil discharged from the hydraulic pump is changed to the first urging pin 71. Is input to the second pressure chamber 82 corresponding to. When the load of the hydraulic actuator driven by the hydraulic oil discharged from another hydraulic pump increases, the pressure of the hydraulic oil discharged from the hydraulic pump increases. That is, the signal pressure due to the hydraulic oil discharged from the other hydraulic pump increases. The first urging pin 71 is urged toward the urging rod 61 by this signal pressure. Accordingly, the first urging pin 71 urges the swash plate 40 (contact surface 42) via the urging rod 61.

  Further, a signal pressure corresponding to the operation of the air conditioner driven by the same drive source is input to the second pressure chamber 82 corresponding to the other first urging pin 71. For example, another hydraulic circuit is branched and connected to the second pressure chamber 82 corresponding to the first urging pin 71. Further, a valve such as a solenoid valve (solenoid valve) is provided in the hydraulic oil flow path between the branch point from the hydraulic circuit and the second pressure chamber 82. When the air conditioner is not operating, the hydraulic oil flow path is closed by the valve, and when the air conditioner is activated, the signal (electrical signal) is received and the valve operates to open the hydraulic oil flow path. Thus, while the air conditioner is not operating, no signal pressure is input to the second pressure chamber 82 corresponding to the first urging pin 71, and when the air conditioner is activated, another hydraulic circuit is connected to the second pressure chamber 82. The signal pressure is input from. The first urging pin 71 is urged toward the urging rod 61 by this signal pressure. Accordingly, the first urging pin 71 urges the swash plate 40 (contact surface 42) via the urging rod 61.

  The urging force for urging the urging rod 61 to the swash plate 40 (contact surface 42), that is, the urging force to the swash plate 40 by the second urging means 60 is applied to the urging rod 61 of the first urging pin 71. The sum of the energies of The moment around the tilting axis of the swash plate 40 due to the biasing force of the second biasing means 60 (the clockwise moment in FIG. 1) is about the tilting axis of the swash plate 40 due to the biasing force of the first biasing means 50. When it becomes larger than the moment (counterclockwise moment in FIG. 1), the swash plate 40 tilts so that its tilt angle becomes small, and the swash plate 40 tilts by the urging force of the second urging means 60. When the moment around the axis and the moment around the tilt axis of the swash plate 40 due to the biasing force of the first biasing means 50 are balanced, the swash plate 40 stops tilting. Thereby, the flow rate of the hydraulic oil discharged from the hydraulic pump 10 decreases.

  In the hydraulic pump 10 of the present embodiment, the same drive in which the load of the hydraulic actuator driven by the hydraulic oil discharged from the hydraulic pump 10 is increased when the operator does not operate or finely operates the operation lever. The second urging means 60 is attached when at least one of the cases where the load of another hydraulic pump driven by the power source increases or the operation of an external device such as an air conditioner driven by the same power source operates. As the force increases, the swash plate 40 tilts so that its tilt angle decreases, and the flow rate of the hydraulic oil discharged from the hydraulic pump 10 decreases. Thereby, it is possible to effectively prevent a stall of a drive source such as a diesel engine that drives the hydraulic pump 10. In addition, waste of fuel consumed by the drive source can be reduced, and the energy saving performance of the hydraulic device including the hydraulic pump 10 can be effectively improved.

  The hydraulic pump 10 according to the present embodiment is a cylinder block 30 that rotates around a rotation axis A, and is formed with a plurality of cylinder holes 32 extending along the direction of the rotation axis A, and each cylinder hole 32. A piston 38 slidably held in the cylinder block 30 and a swash plate 40 for sliding the pistons 38 in the cylinder holes 32 by rotating the cylinder block 30 around the rotation axis A. The swash plate 40 configured to change the tilt angle, the first biasing means 50 for biasing the swash plate 40 in the direction in which the tilt angle of the swash plate 40 increases, and the tilt angle of the swash plate 40 are And a second urging means 60 for urging the swash plate 40 in a direction of decreasing, and the second urging means 60 has an urging rod 61 for urging the swash plate 40. In the rear end surface 61b opposite to the swash plate 40 in FIG. At least one of the flow rate control signal pressure and horsepower shift signal pressure acts.

  According to such a hydraulic pump 10, an energizing force that causes a relatively large component size by causing at least one of a flow control signal pressure and a horsepower shift signal pressure to act on the rear end surface 61 b of the energizing rod 61. The piston can be omitted, and the enlargement of the hydraulic pump 10 can be effectively suppressed.

  Further, according to such a hydraulic pump 10, the flow control signal pressure and / or the horsepower shift signal pressure acts on the entire rear end surface 61 b of the urging rod 61, and the longitudinal direction of the urging rod 61 Generation of a moment that rotates around an orthogonal axis can be effectively suppressed. Therefore, the wear of the urging rod 61 and the first guide portion 23 and the occurrence of hysteresis with respect to the position of the urging rod 61 can be suppressed. That is, the hydraulic pump 10 can be operated stably.

  In the hydraulic pump 10 of the present embodiment, the flow control signal pressure acts on the rear end surface 61b.

  In the hydraulic pump 10 of the present embodiment, the flow control signal pressure is a negative flow control signal pressure.

  According to such a hydraulic pump 10, the urging force of the second urging means 60 is increased when the hydraulic actuator is not operated and is finely operated, and the swash plate 40 is tilted so that its tilt angle is decreased. As a result, the flow rate of the hydraulic oil discharged from the hydraulic pump 10 decreases. Thereby, it is possible to effectively prevent a stall of a drive source such as a diesel engine that drives the hydraulic pump 10. In addition, waste of fuel consumed by the drive source can be reduced, and the energy saving performance of the hydraulic device including the hydraulic pump 10 can be effectively improved. The flow control signal pressure may be a load sensing flow control signal pressure.

  The hydraulic pump 10 according to the present embodiment further includes a guide portion 23 that guides the side surface 61c of the urging rod 61, and pressure oil from another pump is supplied between the side surface 61c and the guide portion 23. .

  According to such a hydraulic pump 10, the pressure oil discharged from another pump is forcibly supplied at a predetermined pressure between the side surface 61 c and the first guide portion 23, whereby the urging rod 61 is moved. It is possible to smoothly move, and the hydraulic oil can be stably discharged by the hydraulic pump 10, and friction that may occur between the side surface 61c of the biasing rod 61 and the first guide portion 23 is reduced. Thus, the occurrence of hysteresis about the position of the urging rod 61 can be suppressed.

  In the hydraulic pump 10 of the present embodiment, the second urging means 60 further includes an urging pin 71, and the urging pin 71 moves the urging rod 61 according to the signal pressure corresponding to the urging pin 71. The swash plate 40 is urged through.

  According to such a hydraulic pump 10, in addition to the flow control signal pressure and / or the horsepower shift signal pressure acting on the rear end surface 61b of the urging rod 61, the signal pressure due to the hydraulic oil discharged from the hydraulic pump 10 is the same. The urging rod 61 is attached to the swash plate 40 also by other signal pressures such as a signal pressure from another hydraulic pump driven by the drive source and a signal pressure corresponding to the operation of the air conditioner driven by the same drive source. Can be biased towards. That is, the flow rate of the pressure oil discharged from the hydraulic pump 10 can be controlled based on a signal pressure other than the flow control signal pressure and / or the horsepower shift signal pressure. Therefore, the flow rate of the pressure oil discharged from the hydraulic pump 10 can be controlled with a higher degree of freedom.

  Note that various modifications can be made to the above-described embodiment. Hereinafter, modified examples will be described with reference to the drawings as appropriate. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted.

  FIG. 3 is a diagram illustrating a modification of the hydraulic pump 10 and is a diagram for explaining the signal pressure P input to the first pressure chamber 81 of the hydraulic pump 10. In the example shown in FIG. 3, the signal pressure P that is at least one of the flow control signal pressure and the horsepower shift signal pressure is input to the first pressure chamber 81 through the orifice 91. That is, the signal pressure P acts on the rear end surface 61 b of the urging rod 61 through the orifice 91.

  When the hydraulic pump, control valve, and each actuator constitute a closed hydraulic circuit (closed circuit), the pressure oil is input to the first pressure chamber via these hydraulic pump, control valve, and each actuator. The signal pressure P may oscillate. When the signal pressure P oscillates, the operation of the urging rod becomes unstable, and the flow rate of the pressure oil discharged from the hydraulic pump becomes unstable. On the other hand, in the hydraulic pump 10 of this modification, the amplitude can be reduced by the orifice 91 and the signal pressure P can be input to the first pressure chamber. Accordingly, the operation of the urging rod and the flow rate of the pressure oil discharged from the hydraulic pump can be stabilized.

  FIG. 4 is a diagram illustrating another modification of the hydraulic pump 10 and is a diagram for explaining the signal pressure P input to the first pressure chamber 81 of the hydraulic pump 10. In the example shown in FIG. 4, the signal pressure P that is at least one of the flow control signal pressure and the horsepower shift signal pressure is input to the first pressure chamber 81 via the slow return mechanism 93. That is, the signal pressure P acts on the rear end surface 61 b of the urging rod 61 via the slow return mechanism 93.

  The slow return mechanism 93 has an orifice 94 and a check valve 95 connected in parallel to each other. The check valve 95 of this modification is configured so that the pressure oil flowing out from the first pressure chamber 81 can pass but the pressure oil flowing into the first pressure chamber 81 cannot pass. The check valve 95 is not limited to this. The check valve 95 is configured to allow the pressure oil flowing into the first pressure chamber 81 to pass therethrough but not allow the pressure oil flowing out from the first pressure chamber 81 to pass therethrough. May be.

  According to this modification, a slow return function can be added to the hydraulic pump 10. In particular, in the illustrated example, when the tilt angle of the swash plate 40 is increased by the flow rate increase signal from the control valve to increase the flow rate of the pressure oil discharged from the hydraulic pump 10, that is, the urging rod 61 is connected to the swash plate. In the case of moving to the opposite side to 40, the pressure oil in the first pressure chamber 81 passes through the check valve 95 of the slow return mechanism 93 and quickly flows out. When the tilt angle is decreased to reduce the flow rate of the pressure oil discharged from the hydraulic pump 10, that is, when the urging rod 61 is moved toward the swash plate 40, the pressure oil is supplied to the orifice 94 of the slow return mechanism 93. Slowly flows into the first pressure chamber 81.

  FIG. 5 is a diagram illustrating still another modified example of the hydraulic pump 10 and is a diagram for explaining the signal pressure P input to the first pressure chamber 81 of the hydraulic pump 10. In the example shown in FIG. 5, the signal pressure P, which is at least one of the flow control signal pressure and the horsepower shift signal pressure, is generated by converting the electrical signal into hydraulic pressure by the electromagnetic proportional valve 97.

  In the illustrated example, the pressure oil from the oil supply source S passes through the electromagnetic proportional valve 97 and is input to the first pressure chamber 81 as the signal pressure P. The electromagnetic proportional valve 97 receives a flow control signal and / or a horsepower shift signal as an electrical signal, and adjusts the opening of the flow path of the pressure oil from the oil supply source S according to the electrical signal.

  According to the present modification, the flow rate control signal and / or the horsepower shift signal can be handled as an electrical signal, so that hydraulic piping can be reduced and the hydraulic pump 10 can be further downsized.

  FIG. 6 is a diagram illustrating still another modified example of the hydraulic pump 10 and is a diagram for explaining the signal pressure P input to the first pressure chamber 81 of the hydraulic pump 10. In the example shown in FIG. 6, both the flow control signal pressure P <b> 1 and the horsepower shift signal pressure P <b> 2 are input to the first pressure chamber 81 through the shuttle valve 99. In the shuttle valve 99, only the signal pressure having a relatively high pressure among the two input signal pressures P1 and P2 can pass, and the relatively low pressure of the two input signal pressures P1 and P2. The signal pressure having a cannot pass through. Only one of the signal pressures P 1 and P 2 that has passed through the shuttle valve 99 is input to the first pressure chamber 81 as the signal pressure P. That is, the signal pressure P is a signal pressure having a relatively high pressure among the flow control signal pressure and the horsepower shift signal pressure.

  According to this modification, a signal pressure having a relatively high pressure out of the flow control signal pressure P1 and the horsepower shift signal pressure P2 can be selectively input to the first pressure chamber 81.

  As yet another modification, as shown in FIG. 7, the signal pressure P that has passed through the shuttle valve 99 may further pass through the orifice 91 and be input to the first pressure chamber 81. Further, as shown in FIG. 8, the signal pressure P that has passed through the shuttle valve 99 may further pass through the slow return mechanism 93 and be input to the first pressure chamber 81.

  FIGS. 9 and 10 are diagrams showing still another modification of the hydraulic pump 10 and showing the positional relationship between the urging rod 61 and the lubricating oil supply hole 68. FIG. 9 is a diagram showing the positional relationship between the urging rod 61 and the lubricating oil supply hole 68 when the urging rod 61 is located closest to the swash plate 40, and FIG. It is a figure which shows the positional relationship of the urging | biasing rod 61 and the supply hole 68 when the rod 61 is most located in the swash plate 40 side.

  In the example shown in FIGS. 9 and 10, the guide portion 23 is provided with a supply hole 68 for supplying pressure oil from another pump between the side surface 61 c of the urging rod 61 and the guide portion 23. ing. As shown in FIG. 9, the supply hole 68 faces the oil retaining groove 65 of the urging rod 61 when the urging rod 61 is located closest to the swash plate 40. The supply hole 68 also faces the oil retaining groove 65 of the urging rod 61 when the urging rod 61 is positioned closest to the swash plate 40 as shown in FIG. That is, the supply hole 68 faces the oil retaining groove 65 at any position during the forward / backward movement along the guide portion 23 of the urging rod 61. In other words, the oil retaining groove 65 faces the supply hole 68 at any position during the forward / backward movement along the guide portion 23 of the urging rod 61.

  According to such a hydraulic pump 10, the supply hole 68 and the oil retaining groove 65 can be communicated with each other regardless of the position where the urging rod 61 is moving forward and backward. That is, pressure oil from other pumps can always be supplied into the oil retaining groove 65. Therefore, it is possible to stably perform the lubrication between the side surface 61c of the urging rod 61 and the guide portion 23.

  FIG. 11 is a cross-sectional view showing still another modified example of the hydraulic pump 10. The hydraulic pump 10 of this modification is a so-called split flow structure hydraulic pump having the function of two pumps with one pump, and outputs two signal pressures Pa and Pb by hydraulic oil discharged from the hydraulic pump 10. Is done.

  In the illustrated example, the urging pin unit 70 includes a second urging pin 72, an adjuster 77, and a unit case 76. The second urging pin 72 has a large-diameter portion having a relatively large diameter, and a small-diameter portion having a relatively small diameter adjacent to the urging rod 61 opposite to the large-diameter portion. Yes. Each of the large diameter portion and the small diameter portion is formed in a columnar shape, and has a circular cross section when viewed along the longitudinal direction of the second urging pin 72. The central axis of the cylinder that forms the large diameter portion coincides with the central axis of the cylinder that forms the small diameter portion. Moreover, the large diameter part and the small diameter part are integrally formed.

  In the unit case 76, a third pressure chamber 83 and a fourth pressure chamber 84 are formed. From the surface of the second biasing pin 72 facing away from the biasing rod 61 of the large-diameter portion, the smaller-diameter portion is formed. The exposed part is located in the third pressure chamber 83, and the surface of the second biasing pin 72 facing the side opposite to the biasing rod 61 is located in the fourth pressure chamber 84. In the illustrated example, the area of the portion exposed from the small diameter portion of the surface facing the biasing rod 61 of the large diameter portion and the area of the surface facing the biasing rod 61 of the small diameter portion are the following: Are equal.

  Two signal pressures Pa and Pb due to the hydraulic oil discharged from the hydraulic pump 10 are input to the pressure chambers 83 and 84, respectively. That is, the signal pressure Pa is input to the third pressure chamber 83 and acts on the portion of the surface facing the opposite side of the large-diameter biasing rod 61 and exposed from the small-diameter portion to attach the second biasing pin 72. Energize toward the force rod 61. The signal pressure Pb is input to the fourth pressure chamber 84 and acts on the surface of the small-diameter portion facing away from the biasing rod 61 to bias the second biasing pin 72 toward the biasing rod 61. . At this time, the urging force that urges the second urging pin 72 toward the urging rod 61 is the sum of the urging force by the signal pressure Pa and the urging force by the signal pressure Pb.

  In the split-flow structure hydraulic pump 10, when the biasing rod 61 is biased via the biasing pin with the two signal pressures Pa and Pb generated by the hydraulic oil discharged from the hydraulic pump 10, the two biasing forces are applied. A pin is required. On the other hand, the urging rod 61 is directed toward the swash plate 40 by using one second urging pin 72 according to the sum of the two signal pressures Pa and Pb due to the hydraulic oil discharged from the hydraulic pump 10. Can be energized. Therefore, the number of parts of the urging pin unit 70 can be reduced.

  Further, the second urging pin 72 of this modification also has the function of the adjustment pin 73 in the hydraulic pump 10 shown in FIG. That is, the position of the second urging pin 72 in the longitudinal direction can be adjusted by the adjuster 77. In this case, one second urging pin 72 performs the functions of three pins, that is, two urging pins and one adjustment pin, and the number of parts of the urging pin unit 70 is further increased. Can be reduced.

  FIG. 12 is a cross-sectional view showing still another modification of the hydraulic pump 10. Similar to the modification described with reference to FIG. 11, the hydraulic pump 10 of this modification is a so-called split flow structure hydraulic pump having a function of two pumps by one pump, and is discharged from the hydraulic pump 10. Two signal pressures are output by the hydraulic fluid.

  In the illustrated example, the urging pin unit 70 includes a second urging pin 72, an adjuster 77, and a unit case 76. The second urging pin 72 is formed in a cylindrical shape, and has a circular cross section when viewed along the longitudinal direction of the second urging pin 72. A fifth pressure chamber 85 is formed in the unit case 76, and a surface of the second urging pin 72 facing the urging rod 61 is located in the fifth pressure chamber 85.

The fifth pressure chamber 85 is inputted with an intermediate pressure Pc of two signal pressures by the hydraulic oil discharged from the hydraulic pump 10. The intermediate pressure Pc is a signal pressure having a pressure intermediate between the two signal pressures. When the two signal pressures are Pa and Pb,
Pc = (Pa + Pb) / 2 (1)
It becomes. As the intermediate pressure Pc, for example, “intermediate pressure P ′” generated in the “pressure communication passage 54” by the pressure oil flowing out from the “opening hole 53” in JP-A-6-307330 can be used.

  According to this modification, the same effects as those of the modification described with reference to FIG. 11 can be exhibited. Furthermore, according to this modification, the second urging pin 72 can be formed into a simple cylindrical shape, and the pressure chamber provided in the unit case 76 corresponding to the second urging pin 72 is provided as one fifth. The pressure chamber 85 can be used. Therefore, the structure of the urging pin unit 70 can be simplified.

  In the modified example described with reference to FIGS. 11 and 12, one or more first urging pins 71 may be provided in addition to the second urging pins 72.

  As still another modified example, in the embodiment described with reference to FIGS. 1 and 2, the hydraulic pump 10 has the four first urging pins 71, but is not limited thereto. The hydraulic pump 10 may have two, three, five or more first urging pins 71.

  In addition, although the some modification with respect to embodiment mentioned above was demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

DESCRIPTION OF SYMBOLS 10 Hydraulic pump 14 Gear pump 16 Rotating shaft 20 Housing 21 1st housing block 23 1st guide part 29 Recess 22 2nd housing block 25 Rotating shaft 30 Cylinder block 32 Cylinder hole 35 Intake / exhaust plate 38 Piston 39 Cylinder chamber 40 Swash plate 41 Sliding Surface 42 Abutment surface 43 Shoe 50 First urging means 51 First retainer 52 Second retainer 54 First spring 55 Second spring 60 Second urging means 61 Energizing rod 61a Front end surface 61b Rear end surface (end surface)
61c Side surface 65 Oil retaining groove 68 Supply hole 70 Energizing pin unit 71 First energizing pin 72 Second energizing pin 73 Adjustment pin 75 Second guide portion 76 Unit case 77 Adjuster 78 Protruding portion 81 First pressure chamber 82 Second Pressure chamber 83 Third pressure chamber 84 Fourth pressure chamber 85 Fifth pressure chamber 91 Orifice 93 Slow return mechanism 94 Orifice 95 Check valve 97 Proportional solenoid valve 99 Shuttle valve A Rotating axis L Supply line P Signal pressure S Oil supply source

Claims (10)

A cylinder block that rotates about a rotation axis, wherein a plurality of cylinder holes are formed;
A piston slidably held in each cylinder hole;
A swash plate for sliding each piston in each cylinder hole by rotating the cylinder block around the rotation axis, and a swash plate configured to change its tilt angle;
First urging means for urging the swash plate in a direction in which the tilt angle of the swash plate is increased;
Second urging means for urging the swash plate in a direction in which the tilt angle of the swash plate decreases,
The second biasing means has a biasing rod that biases the swash plate,
A hydraulic pump in which at least one of a flow control signal pressure and a horsepower shift signal pressure acts on an end surface of the biasing rod opposite to the swash plate.   The hydraulic pump according to claim 1, wherein the flow control signal pressure acts on the end face.   The hydraulic pump according to claim 2, wherein the flow control signal pressure is a negative flow control signal pressure.   The hydraulic pump according to claim 1, wherein the flow control signal pressure or the horsepower shift signal pressure acts on the end face via an orifice.   The hydraulic pump according to claim 1, wherein the flow control signal pressure or the horsepower shift signal pressure acts on the end face via a slow return mechanism.   The hydraulic pump according to any one of claims 1 to 5, wherein the flow control signal pressure or the horsepower shift signal pressure is a signal pressure obtained by converting an electric signal into a hydraulic pressure by an electromagnetic proportional valve.   The hydraulic pump according to any one of claims 1 to 6, wherein a signal pressure having a relatively high pressure among the flow control signal pressure and the horsepower shift signal pressure acts on the end face. A guide portion for guiding a side surface of the biasing rod;
The hydraulic pump according to claim 1, wherein pressure oil from another pump is supplied between the side surface and the guide portion. The guide portion is provided with a supply hole for supplying pressure oil from the other pump between the side surface and the guide portion,
The side surface is provided with an oil holding groove for holding pressure oil supplied from the supply hole,
The hydraulic pump according to claim 8, wherein the oil retaining groove faces the supply hole at any position during the forward / backward movement along the guide portion of the biasing rod. The second biasing means further includes a biasing pin,
The hydraulic pump according to claim 1, wherein the urging pin urges the swash plate via the urging rod in accordance with a signal pressure corresponding to the urging pin.