JP2020186677A - Hydraulic pump, working machine, and method for cooling hydraulic pump - Google Patents

Abstract

To efficiently cool a hydraulic pump.SOLUTION: A hydraulic pump 10 comprises: a supply/discharge plate 35 comprising a supply hole and a discharge hole for hydraulic oil; a cylinder block 30 comprising a plurality of cylinder holes 32 to/from which the hydraulic oil is supplied/discharged via the supply/discharge plate 35, and to be rotated while being slid on the supply/discharge plate 35; pistons 38 movably provided in the plurality of cylinder holes 32 respectively; a swash plate 40 for regulating movement of the pistons 38; a shoe 43 provided between the pistons 38 and the swash plate 40; and an injection part 70 for injecting oil supplied from a hydraulic source 14 toward at least one of the supply/discharge plate 35, the cylinder block 30, the pistons 38, the swash plate 40, and the shoe 43.SELECTED DRAWING: Figure 2

Description

The present invention relates to a hydraulic pump, a work machine provided with the hydraulic pump, and a method for cooling the hydraulic pump.

In a work machine such as a hydraulic excavator, a hydraulic pump is used as a drive source for driving a hydraulic actuator such as a hydraulic cylinder. As the hydraulic pump, for example, a variable displacement hydraulic pump is used. Variable displacement hydraulic pumps generally have a plurality of cylinder holes, a rotatably arranged cylinder block, a piston movably held in each cylinder hole, and a tilt angle (tilt angle). It has a swash plate that controls the amount of movement of the piston according to the size of the swash plate, and a mechanism for changing the tilt angle of the swash plate.

For example, Patent Document 1 discloses a variable displacement type swash plate type 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 sucks and discharges hydraulic oil to a cylinder block that rotates around a swash plate, a piston that is movably held in each cylinder hole formed in the cylinder block, and a cylinder block. A supply / discharge plate with multiple through holes for this purpose, a swash plate with a changeable tilt angle, a shoe connected to a piston and moving on the swash plate, and a large tilt angle of the swash plate. It has a first pressing means for pressing the swash plate in such a direction, and a second pressing means for pressing the swash plate in a direction in which the tilt angle of the swash plate becomes smaller. Such a hydraulic pump has an advantage that the tilt angle of the swash plate can be adjusted by a simple mechanism.

JP-A-2018-3609

The hydraulic pump disclosed in Patent Document 1 slides (rubs) with respect to each other, such as between a cylinder block and a piston, between a cylinder block and a supply / discharge plate, and between a swash plate and a shoe. It has a friction part. In this friction portion, frictional heat is generated by the friction between the two members. In particular, when the hydraulic pump is operating at a high speed or when a high load is generated on the hydraulic pump, a large amount of frictional heat is generated in the friction portion, and the member may become hot. In this case, the temperature of the oil that comes into contact with the member, for example, the hydraulic oil that passes through the cylinder block toward the hydraulic actuator or the oil that is sealed in the hydraulic pump, rises and the viscosity of these oils decreases. As a result, the oil film formed between the two members that rub against each other becomes thin, and the two members may wear or break due to direct contact and rubbing against each other.

The present invention has been made in consideration of such a point, and an object of the present invention is to efficiently cool a hydraulic pump.

The hydraulic pump according to the present invention
A supply / discharge plate having a hydraulic oil supply hole and a discharge hole,
A cylinder block having a plurality of cylinder holes for supplying and discharging the hydraulic oil through the supply / discharge plate and rotating while sliding with respect to the supply / discharge plate.
A piston movablely provided in each of the plurality of cylinder holes,
A swash plate that regulates the movement of the piston,
A shoe provided between the piston and the swash plate,
It includes an ejection portion that ejects oil supplied from a hydraulic source toward at least one of the supply / discharge plate, the cylinder block, the piston, the swash plate, and the shoe.

In the hydraulic pump of the present invention
It has a main pump that supplies hydraulic oil to the hydraulic actuator and a pilot pump that supplies pilot oil to the operation unit for workers.
The hydraulic source may be the pilot pump.

The hydraulic pump according to the present invention
It has a main pump that supplies hydraulic oil to the hydraulic actuator and a pilot pump that supplies pilot oil to the operation unit for workers.
The main pump
A supply / discharge plate having a hydraulic oil supply hole and a discharge hole,
A cylinder block having a plurality of cylinder holes for supplying and discharging the hydraulic oil through the supply / discharge plate and rotating while sliding with respect to the supply / discharge plate.
A piston movablely provided in each of the plurality of cylinder holes,
A swash plate that regulates the movement of the piston,
A shoe provided between the piston and the swash plate,
It includes an ejection portion that ejects oil supplied from the pilot pump toward at least one of the supply / discharge plate, the cylinder block, the piston, the swash plate, and the shoe.

The work machine according to the present invention
It is equipped with the above-mentioned hydraulic pump.

The method for cooling a hydraulic pump according to the present invention is
The supply / discharge plate having a supply / discharge plate having a supply hole and a discharge hole for hydraulic oil, and a plurality of cylinder holes for supplying and discharging the hydraulic oil through the supply / discharge plate to supply oil supplied from a hydraulic source. A cylinder block that rotates while sliding, a piston that is movably provided in each of the plurality of cylinder holes, a swash plate that regulates the movement of the piston, and a shoe that is provided between the piston and the swash plate. It spouts toward at least one.

According to the present invention, the hydraulic pump can be cooled efficiently.

FIG. 1 is a diagram for explaining one embodiment according to the present invention, and is a diagram showing an example of a work machine incorporating a hydraulic pump. FIG. 2 is a diagram showing a cross section of a hydraulic pump. FIG. 3 is a cross-sectional view showing another example of the hydraulic pump. FIG. 4 is a diagram showing still another example of the hydraulic pump. FIG. 5 is a schematic view showing an example of the positional relationship between the friction member of the hydraulic pump and the ejection portion. FIG. 6 is a schematic view showing another example of the positional relationship between the friction member and the ejection portion.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, the scale, aspect ratio, etc. are appropriately changed from those of the actual product and exaggerated for the convenience of illustration and comprehension.

In addition, as used in this specification, the terms such as "parallel", "orthogonal", and "identical" and the values of length and angle, etc., which specify the shape and geometric conditions and their degrees, are strictly defined. Without being bound by the meaning, we will interpret it including the range where similar functions can be expected.

1 to 6 are diagrams for explaining one embodiment according to the present invention. Of these, FIG. 1 is a diagram showing an example of a work machine 1 in which a hydraulic pump 10 is incorporated.

The work machine 1 of the present embodiment is a hydraulic excavator, and is attached to a lower frame 2 provided with a crawler, an upper frame 3 provided so as to be swivel with respect to the lower frame 2 by driving a swivel motor 4, and an upper frame 3. The boom 5 is provided, an arm 6 attached to the boom 5, and a bucket 7 attached to the arm 6 are provided. Hydraulic cylinders 9 are provided between the upper frame 3 and the boom 5, between the boom 5 and the arm 6, and between the arm 6 and the bucket 7.

The work machine 1 includes a hydraulic pump 10. The hydraulic pump 10 is driven by power from a power source such as a diesel engine (not shown), and delivers hydraulic oil for driving the hydraulic actuator to each hydraulic actuator. In the illustrated work machine 1, the swivel motor 4, the traveling motor 8, and the hydraulic cylinder 9 function as hydraulic actuators. When the upper frame 3 is swiveled in the work machine 1, the swivel motor 4 is rotationally driven by the hydraulic oil delivered from the hydraulic pump 10, and this rotational driving force is transmitted to the upper frame 3. When the work machine 1 is driven, the traveling motor 8 is rotationally driven by the hydraulic oil delivered from the hydraulic pump 10, and this rotational driving force is transmitted to the crawler. When driving the boom 5, arm 6 or bucket 7, the hydraulic cylinder 9 is expanded and contracted by the hydraulic oil sent from the hydraulic pump 10, and this expansion and contraction driving force is transmitted to the boom 5, arm 6 or bucket 7. ..

FIG. 2 is a diagram showing a cross section of the hydraulic pump 10. The hydraulic pump 10 shown in FIG. 2 includes a main pump 12 and a pilot pump 14 attached to the main pump 12. The main pump 12 is a so-called swash plate type variable displacement hydraulic pump. The main pump 12 outputs a driving force based on the discharge of hydraulic oil from the cylinder hole 32 (and the supply of hydraulic oil to the cylinder hole 32), which will be described later. More specifically, by rotating the rotating shaft 25 by the power from a power source such as an engine, the cylinder block 30 connected to 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. The 38 is reciprocated. In response to the reciprocating operation of the piston 38, hydraulic oil is discharged from some of the cylinder holes 32 and hydraulic oil is sucked into the other cylinder holes 32 to realize a hydraulic pump. The pilot pump 14 is a pump that supplies pilot oil having a constant pressure to an operation unit for an operator such as an operation lever, and can be configured by a gear pump as an example.

The main pump 12 includes a housing 20, a rotating shaft 25, a cylinder block 30, a swash plate 40, a first pressing means 50, a second pressing means 60, and a ejection portion 70. The housing 20 has a first housing block 21 and a second housing block 22 connected to the first housing block 21 by a fastening means (not shown) or the like. The housing 20 houses a part of the rotating shaft 25, a cylinder block 30, a swash plate 40, and a first pressing means 50. In the example shown in FIG. 2, inside the first housing block 21, a supply port (not shown) leading to a plurality of cylinder holes 32 via one end of the rotating shaft 25 and a supply / discharge plate (valve plate) 35. And a discharge port, and a guide portion 23 for guiding the pressing rod 61, which will be described later, are arranged. Further, the supply port is provided so as to penetrate the first housing block 21 and leads to a hydraulic source (not shown) provided outside the hydraulic pump 10.

A hole 24a for a rotating shaft into which the rotating shaft 25 is inserted is formed in the first housing block 21, and the rotating shaft 25 is rotatably supported around the rotating axis A by a bearing 28a in the hole 24a for the rotating shaft. .. 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 pilot pump 14 via a spline coupling portion 26a formed at the one end.

The second housing block 22 is formed with a hole 24b for a rotating shaft through which the rotating shaft 25 penetrates, and the rotating shaft 25 extends from one end to the other end through the cylinder block 30 and the swash plate 40. There is. The rotary shaft 25 is rotatably supported around the rotary axis A by a bearing 28b arranged in the rotary shaft hole 24b at the other end. In the illustrated example, the other end of the rotating shaft 25 projects 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. To.

In the example shown in FIG. 2, the rotating shaft 25 is spline-coupled to the cylinder block 30 at a spline coupling portion 26c provided at a portion penetrating the cylinder block 30. Due to the spline coupling with the cylinder block 30, the rotating shaft 25 can move independently of the cylinder block 30 in the direction of the rotating axis A, but rotates integrally with the cylinder block 30 in the rotating direction around the rotating axis A. To do. Further, the rotating shaft 25 is rotatably supported by the bearing 28a in the first housing block 21 and rotatably supported by the bearing 28b in the second housing block 22 so as not to come into contact with the swash plate 40. ing. Therefore, the rotating shaft 25 is provided so as to be rotatable in the rotational direction around the rotating axis A together with the cylinder block 30 without being hindered by members other than the cylinder block 30.

The pilot pump 14 is coupled to the first housing block 21 of the main pump 12 on the opposite side of the second housing block 22 along the rotation axis A by a fastening means (not shown) or the like. In the example shown in FIG. 2, the pilot pump 14 has a rotating shaft 16. The rotation shaft 16 is rotatably arranged 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 pilot pump 14 via a spline coupling portion 26a formed at the one end. Specifically, one end of the rotary shaft 25 and the sleeve 18 are connected via a spline coupling portion 26a, and the rotary shaft 16 and the sleeve 18 are connected via a spline coupling portion 17a formed on the rotary shaft 16. It is connected.

When the rotating shaft 25 connected to the power source of the engine or the like rotates by the driving force from the power source, the rotating shaft 25 and the rotating shaft 16 rotate integrally around the rotating axis A. As a result, the pilot oil 14 has the pilot oil having a constant pressure supplied to the operation unit for the operator such as the operation lever in the work machine 1 in which the hydraulic pump 10 is incorporated. Further, in the present embodiment, a part of the oil delivered from the pilot pump 14 is supplied to the ejection portion 70 of the main pump 12 through the supply line L described later. Since the pilot pump 14 can be configured in the same manner as a known gear pump as an example, the description of the specific configuration will be omitted.

The cylinder block 30 rotates about the rotation axis A together with the rotation axis 25, and has a plurality of cylinder holes 32 formed around the rotation axis A. In particular, in the example shown in FIG. 2, each cylinder hole 32 is provided so as to extend in a direction parallel to the rotation axis A. Not limited to this, the cylinder hole 32 may be provided so as to extend along a 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 (equally spaced) on the same circumference when viewed from the direction along the rotation axis A. It is preferable to arrange at.

An opening 32a leading to each of the plurality of cylinder holes 32 is formed at the end of the cylinder block 30 on the side opposite to the side on which the swash plate 40 is provided. Further, the supply / discharge plate 35 is arranged so as to face the end of the cylinder block 30 on the side opposite to the side on which the swash plate 40 is provided. The supply / discharge plate 35 has a hydraulic oil supply hole and a discharge hole (not shown). The supply hole communicates with a supply port (not shown) provided in the first housing block 21, and the discharge hole communicates with a discharge port (not shown) provided in the first housing block 21. 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 hydraulic oil is communicated through these supply ports and discharge ports. Is supplied and discharged. Further, in the example shown in FIG. 2, the springs 44 and retainers 45a and 45b described later are accommodated around the rotating shaft 25 at the end of the cylinder block 30 opposite to the side on which the swash plate 40 is provided. A recess 30a is formed.

The supply / discharge plate 35 is fixed to the first housing block 21, and is stationary with respect to the housing 20 (first housing block 21) even when the cylinder block 30 rotates together with the rotating shaft 25. Therefore, the cylinder hole 32 communicating with each of the supply port and the discharge port is switched via the supply / discharge plate 35 according to the rotation state of the cylinder block 30, and operates in the state where the hydraulic oil is supplied from the supply port and in the discharge port. The state of discharging oil repeatedly comes.

In the hydraulic pump 10 of the present embodiment, the cylinder block 30 rotates while sliding with respect to the supply / discharge plate 35. At this time, the cylinder block 30 and the supply / discharge plate 35 may rub against each other to generate frictional heat. Therefore, the cylinder block 30 and the supply / discharge plate 35 are friction members that generate frictional heat by sliding against each other.

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

In the hydraulic pump 10 of the present embodiment, the piston 38 reciprocates along the direction parallel to the rotation axis A while sliding with respect to the cylinder block 30. At this time, the cylinder block 30 and the piston 38 may rub against each other to generate frictional heat. Therefore, the cylinder block 30 and the piston 38 are friction members that generate frictional heat by sliding against each other.

The swash plate 40 is for moving each piston 38 in each cylinder hole 32 by rotating the cylinder block 30 around the rotation axis A. The swash plate 40 has a flat sliding surface 41 on the side facing the cylinder block 30, and the above-mentioned shoe 43 connected to the end of the piston 38 on the swash plate 40 side is pressed against the sliding surface 41. There is. Further, the swash plate 40 is provided so as to be tiltable, and the reciprocating stroke of the piston 38 changes according to the tilt angle of the swash plate 40 (sliding surface 41). In other words, the swash plate 40 controls the amount of movement of the piston 38 according to the magnitude of the tilt angle. The larger the tilt angle of the swash plate 40 (sliding surface 41), the larger the supply amount and discharge amount of hydraulic oil to the cylinder hole 32 due to the reciprocating movement of each piston 38, and the tilt of the swash plate 40 (sliding surface 41). The smaller the angle, the smaller the supply amount and discharge amount of hydraulic oil to the cylinder hole 32 due to the reciprocating movement of each piston 38. 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. When the tilt angle is 0 degrees, 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. The swash plate 40 has an action surface 42 on the outside of the sliding surface 41 on which the pressing rod 61 described later contacts and the pressing force from the pressing rod 61 acts. In the illustrated example, the working surface 42 is provided so as to be parallel to the sliding surface 41.

In the present embodiment, the 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). Further, 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 rotating shaft 25. The spring 44 and the retainers 45a and 45b are housed in a recess 30a formed around a rotating shaft 25 at an end of the cylinder block 30 opposite to the side on which the swash plate 40 is provided. In the example shown in FIG. 2, the spring 44 is a coil spring and is arranged in the recess 30a in a compressed state between the retainer 45a and the retainer 45b. Therefore, the spring 44 generates a pressing force in the direction in which the spring 44 extends due to its elastic force. The pressing force of the spring 44 is transmitted to the pressing member 47 via the retainer 45b and the connecting member 46. Each shoe 43 is held by the shoe holding member 48, and the pressing member 47 receives the pressing 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. 2, the swash plate 40 can be tilted at various angles, but the pressing force of the spring 44 causes each shoe 43 to tilt with respect to the swash plate 40 regardless of the tilt angle of the swash plate 40. It is properly followed and pressed. As a result, when the piston 38 rotates together with the cylinder block 30, each shoe 43 moves on the swash plate 40 in a circular orbit. In the illustrated example, the end portion of the piston 38 on the swash plate 40 side forms a spherical convex portion, the convex portion of the piston 38 is fitted into the spherical concave portion formed on the shoe 43, and the concave portion of the shoe 43. Spherical bearing structure is formed by the piston 38 and the shoe 43 by being crimped. With this spherical bearing structure, even if the tilt angle of the swash plate 40 changes, each shoe 43 can appropriately move and rotate on the swash plate 40 following the tilt of the swash plate 40.

In the hydraulic pump 10 of the present embodiment, the shoe 43 rotates and moves with respect to the swash plate 40 while sliding. At this time, the shoe 43 and the swash plate 40 may rub against each other to generate frictional heat. Therefore, the shoe 43 and the swash plate 40 are friction members that generate frictional heat by sliding against each other.

The first pressing means 50 presses the swash plate 40 in a direction in which the tilt angle of the swash plate 40 increases. In the example shown in FIG. 2, the first pressing means 50 has a first retainer 51 arranged on the side opposite to the swash plate 40 (first housing block 21 side) and a swash plate 40 side (second housing block 22). It has a second retainer 52 arranged on the side) and springs 54 and 55 arranged between the first retainer 51 and the second retainer 52. The first spring 54 is arranged in a compressed state between the first retainer 51 and the second retainer 52. Therefore, the elastic force of the first spring 54 generates a pressing force in the direction in which the first spring 54 extends. The second spring 55 is arranged inside the first spring 54. Therefore, the winding diameter of the second spring 55 is formed to be smaller than the winding diameter of the first spring 54.

In the example shown in FIG. 2, 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. 2). As a result, while the tilt angle of the swash plate 40 is large, only the pressing force of the first spring 54 acts on the swash plate 40. As the tilt angle of the swash plate 40 becomes smaller, the second spring 55 comes into contact with the first retainer 51 at a certain tilt angle. Further, when the tilt angle of the swash plate 40 becomes smaller, the second spring 55 is also compressed between the first retainer 51 and the second retainer 52, whereby the swash plate 40 has the first spring 54 and the second spring. Both pressing forces of 55 act. Therefore, according to the illustrated first pressing means 50, the pressing 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 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 made movable between the first retainer 51 and the second retainer 52.

The second pressing means 60 exerts a pressing force on the swash plate 40 in the direction opposite to the pressing force on the swash plate 40 by the first pressing means 50. In particular, the second pressing means 60 resists the pressing force of the first pressing means 50 in the direction in which the tilt angle of the swash plate 40 increases, and the swash plate 40 decreases in the direction in which the tilt angle of the swash plate 40 decreases. push. In the example shown in FIGS. 2 to 4, the second pressing means 60 has a pressing rod 61. The pressing rod 61 connects a front surface 61a facing the swash plate 40 (working surface 42), a rear surface 61b formed on the opposite side of the front surface 61a along the axis of the pressing rod 61, and the front surface 61a and the rear surface 61b. It has a side surface 61c, and is pushed toward the swash plate 40 by the pressure (flood control) acting on the rear surface 61b. As a result, the swash plate 40 tilts around its tilt axis so that the tilt angle becomes smaller.

The pressing rod 61 has a substantially columnar shape as a whole, and is arranged so as to face the working surface 42 of the swash plate 40 so that its axis is parallel to the rotation axis A. The pressing rod 61 is not limited to the one whose axis is arranged so as to be parallel to the rotation axis A, and the pressing rod 61 may be arranged so that its axis is inclined with respect to the rotation axis A. In the illustrated example, the tip surface 61a has a spherical shape. As a result, even if the angle formed by the swash plate 40 (acting surface 42) and the pressing rod 61 changes due to the change in the tilt angle of the swash plate 40, the pressing force against the swash plate 40 acts from the tip surface 61a. It can be appropriately transmitted to the surface 42. Further, the rear surface 61b of the pressing rod 61 has a flat surface orthogonal to the axis of the pressing rod 61. The rear surface 61b may have an arrangement and a shape that can function as an action surface on which pressure acts, and the specific arrangement and shape thereof are not particularly limited. The "rear surface" refers to a surface that faces substantially the opposite side of the "tip surface".

The first housing block 21 (housing 20) is provided with a guide portion 23 for guiding the side surface 61c of the pressing rod 61, and the pressing rod 61 is movably arranged with respect to the guide portion 23. .. Therefore, a part of the pressing rod 61 is movably held in the guide portion 23. The guide portion 23 is formed of a through hole provided in the first housing block 21 and has a cross-sectional shape complementary to the cross-sectional shape of the pressing rod 61. That is, the guide portion 23 is composed of a cylindrical through hole having a circular cross section. In the example shown in FIGS. 2 to 4, the guide portion 23 is provided integrally with the first housing block 21 (housing 20). If the guide portion 23 is provided integrally with the first housing block 21, the guide portion 23 can be formed by drilling the first housing block 21, and the guide portion 23 can be formed by simple processing. It will be possible. Further, since no additional member is required to provide the guide portion 23, it contributes to the reduction of the number of parts of the hydraulic pump 10 and the cost reduction. The configuration of the guide unit 23 is not limited to this. As an example, a guide portion 23 formed by using a member, which is different from the first housing block 21, for example, a cylindrical shape, may be attached to the housing 20.

The first housing block 21 (housing 20) is formed with a recess 29 communicating with the guide portion 23. A lid member (not shown) is fitted in the recess 29. As a result, a pressure chamber is formed between the rear surface 61b of the pressing rod 61 and the lid member into which oil for generating oil (hydraulic pressure) acting on the rear surface 61b is introduced. As another example, the urging pin unit described in JP-A-2018-3609 may be used instead of the lid member. In this case, the convex portion of the urging pin unit is fitted into the concave portion 29, and the pressure acting on the rear surface 61b acts on the pressing rod 61 via the urging pin.

When pushing the swash plate 40 with the pressing rod 61, the reaction force from the swash plate 40 may act on the pressing rod 61 in a direction inclined with respect to the axial direction of the pressing rod 61. Since the hydraulic pump 10 of the present embodiment has the guide portion 23, even if a force in a direction inclined with respect to the axial direction of the pressing rod 61 acts on the pressing rod 61, the guide portion 23 Since the pressing rod 61 can be appropriately held, the pressing rod 61 can be operated stably. A part of the oil held in the housing 20 is supplied between the side surface 61c of the pressing rod 61 and the guide portion 23, whereby the side surface 61c and the guide portion 23 are lubricated.

The hydraulic pump 10 of the present embodiment has a friction portion between the cylinder block 30 and the piston 38, between the cylinder block 30 and the supply / discharge plate 35, between the swash plate 40 and the shoe 43, and the like. .. In this friction portion, frictional heat is generated by the friction between the two members. In particular, when the hydraulic pump is operating at a high speed or when a high load is generated on the hydraulic pump, a large amount of frictional heat is generated in the friction portion, and the member may become hot. In this case, the temperature of the oil that comes into contact with the member, for example, the hydraulic oil that passes through the cylinder block 30 toward the hydraulic actuator and the oil that is sealed in the hydraulic pump 10, rises and the viscosity of these oils decreases. As a result, the oil film formed between the two members that rub against each other becomes thin, and the two members may wear or break due to direct contact and rubbing against each other.

In order to deal with such a problem, the hydraulic pump 10 of the present embodiment uses the cooling oil (oil) supplied from the hydraulic source as a friction member (supply / discharge plate 35, cylinder block 30, piston 38, swash plate 40, and It has an ejection portion 70 that ejects toward at least one of the shoes 43). The cooling oil ejected from the ejection portion 70 comes into contact with the friction member whose temperature has become high due to the frictional heat and exchanges heat with the friction member, whereby the friction member is cooled.

In the present embodiment, the main pump 12 has a ejection portion 70, and the pilot pump 14 is a hydraulic source for cooling oil. That is, the cooling oil supplied from the pilot pump 14 is ejected from the ejection portion 70 of the main pump 12 toward the friction member, whereby the friction member is cooled. While the hydraulic pump 10 is being driven, oil having a constant pressure is continuously discharged from the pilot pump 14. Therefore, by using the pilot pump 14 as the hydraulic source of the cooling oil, a part of the oil discharged from the pilot pump 14 can be stably supplied to the ejection portion 70 as the cooling oil.

In the example shown in FIGS. 2 to 4, the flow path through which the oil discharged from the pilot pump 14 flows branches at the branch point F. A part of the oil discharged from the pilot pump 14 is supplied as pilot oil from the branch point F to an operation unit for an operator such as an operation lever. The other part of the oil discharged from the pilot pump 14 is supplied to the ejection portion 70 as cooling oil through the supply line L. There is no difference between the oil from the pilot pump 14 to the operation unit through the branch point F and the oil from the pilot pump 14 to the ejection unit 70 through the branch point F as the oil itself. In the present specification, the oil that goes to the operation unit via the branch point F is called the pilot oil due to the function of each oil that can be exhibited at the location supplied from the pilot pump 14, and the oil goes through the branch point F. The oil directed toward the ejection portion 70 is called cooling oil.

In the illustrated example, a relief valve 80 is provided in the middle of the supply line L. The oil heading to the ejection portion 70 via the branch point F passes through the relief valve 80. When the amount of pilot oil consumed in the operation unit is relatively large, the pressure acting on the relief valve 80 due to the oil directed to the ejection unit 70 through the supply line L becomes relatively low and passes through the relief valve 80. The flow rate of the cooling oil toward the ejection portion 70 becomes smaller. On the other hand, when the amount of pilot oil consumed in the operation unit is relatively small, the pressure acting on the relief valve 80 due to the oil directed to the ejection unit 70 through the supply line L becomes relatively high, and the relief valve 80 The flow rate of the cooling oil passing through the above and toward the ejection portion 70 becomes large. As a result, it is possible to effectively reduce the influence on the flow rate of the pilot oil that can be used in the operation unit while using a part of the oil discharged from the pilot pump 14 as the cooling oil.

The hydraulic source of the cooling oil is not limited to the pilot pump 14. For example, another hydraulic pump arranged outside the hydraulic pump 10 may function as a hydraulic source for cooling oil.

The ejection portion 70 has an ejection hole 72 for ejecting cooling oil. The ejection hole 72 extends toward a portion of the friction member to be cooled. The ejection hole 72 is formed so as to pass through the housing 20 (first housing block 21), and has an opening on the inner surface of the housing 20. The portion of the ejection hole 72 opposite to the opening is connected to the supply line L, and the cooling oil discharged from the hydraulic source and supplied to the ejection portion 70 through the supply line L is a friction member from the opening of the ejection hole 72. It is ejected toward the place to be cooled in. In FIGS. 2 to 4, for convenience of illustration, the broken line indicating the ejection hole 72 is shown overlapping with the pressing rod 61, which indicates that the ejection hole 72 passes through the pressing rod 61. It's not a thing.

In the example shown in FIG. 2, the piston 38 reciprocates along the direction parallel to the rotation axis A while sliding with respect to the cylinder block 30. At this time, the cylinder block 30 and the piston 38 rub against each other to generate frictional heat. That is, the friction member is a cylinder block 30 that rubs against the piston 38. In the illustrated example, the ejection hole 72 extends toward the side surface 34 of the cylinder block 30. As a result, the cooling oil ejected from the ejection hole 72 contacts the side surface 34 of the cylinder block 30 and exchanges heat with the cylinder block 30, and cools the cylinder block 30 which has become hot due to friction with the piston 38.

FIG. 3 shows another example of the hydraulic pump 10. In the example shown in FIG. 3, the cylinder block 30 rotates while sliding with respect to the supply / discharge plate 35. At this time, the cylinder block 30 and the supply / discharge plate 35 rub against each other to generate frictional heat. That is, the friction member is a cylinder block 30 that rubs against the supply / discharge plate 35. In the illustrated example, the ejection hole 72 extends toward the end of the supply / discharge plate 35 on the side surface 34 of the cylinder block 30. As a result, the cooling oil ejected from the ejection hole 72 comes into contact with the end of the supply / discharge plate 35 on the side surface 34 of the cylinder block 30 and exchanges heat with the cylinder block 30, and becomes hot due to friction with the supply / discharge plate 35. The cylinder block 30 is cooled. Here, when the cooling oil ejected from the ejection hole 72 comes into contact with the end of the supply / discharge plate 35 on the side surface 34 of the cylinder block 30, at least a part of the cooling oil ejected from the ejection hole 72 is the cylinder block. It means contacting the end of the supply / discharge plate 35 on the side surface 34 of 30.

FIG. 4 shows still another example of the hydraulic pump 10. In the example shown in FIG. 4, the shoe 43 rotates and moves with respect to the swash plate 40 while sliding. At this time, the shoe 43 and the swash plate 40 rub against each other to generate frictional heat. That is, the friction member is a shoe 43 that rubs against the swash plate 40. In the illustrated example, the ejection hole 72 extends towards the shoe 43. As a result, the cooling oil ejected from the ejection hole 72 contacts the shoe 43 and exchanges heat with the shoe 43, and cools the shoe 43 which has become hot due to friction with the swash plate 40. In the illustrated example, the ejection hole 72 is provided so as to extend toward the swash plate 40 so that the cooling oil ejected from the ejection hole 72 comes into contact with the swash plate 40 and exchanges heat with the swash plate 40. You may.

FIG. 5 is a schematic view showing an example of the positional relationship between the friction member of the hydraulic pump 10 and the ejection portion 70, and FIG. 6 is a schematic diagram showing another example of the positional relationship between the friction member and the ejection portion 70. is there. In FIGS. 5 and 6, the cylinder block 30 as an example of the friction member and the ejection hole 72 of the ejection portion 70 are shown when viewed from the direction along the rotation axis A. The arrow around the rotation axis A indicates the rotation direction of the cylinder block 30. In the illustrated cross section, let P be a point located on the extension line of the ejection hole 72 on the side surface 34 of the cylinder block 30. At this time, the straight line connecting the rotation axis A and the point P and the extension line of the ejection hole 72 intersect each other with an angle of less than 180 degrees, particularly an angle of 90 degrees or more and less than 180 degrees. In this case, the cooling oil that has come into contact with the ejection side surface 34 from the ejection hole 72 can flow substantially in the circumferential direction of the friction member (cylinder block 30) along the side surface 34, so that the cooling oil comes into contact with the friction member. Sufficient time can be secured, and the cooling effect of the friction member by the cooling oil can be enhanced.

In the example shown in FIGS. 5 and 6, at the point P, the extension line of the ejection hole 72 is behind the friction member (cylinder block 30) in the rotation direction with respect to the straight line connecting the rotation axis A and the point P. It is inclined to. In this case, the cooling oil ejected from the ejection hole 72 comes into contact with the side surface 34 from a direction inclined to the rear side in the rotation direction, so that the rotation of the friction member is hindered by the contact of the cooling oil. It can be suppressed. In particular, as shown in FIG. 6, the ejection hole 72 extends in a direction inclined with respect to the normal direction to the inner surface of the housing 20 (first housing block 21), thereby connecting the rotation axis A and the point P. When the angle between the connecting straight line and the extension line of the ejection hole 72 is relatively small, it is possible to more effectively suppress the rotation of the friction member from being hindered by the contact of the cooling oil.

In the hydraulic pump 10 described above, when the rotary shaft 25 connected to the power source of the engine or the like rotates by the driving force from the power source, the rotary shaft 25 and the rotary shaft 16 move around the rotary axis A via the sleeve 18. It rotates integrally. A part of the oil discharged from the pilot pump 14 is supplied as pilot oil from the branch point F to the operation part for the operator such as the operation lever, and the other part is the cooling oil through the supply line L. Is supplied toward the ejection portion 70. In the example shown in FIGS. 2 to 4, the cooling oil passing through the supply line L flows to the ejection portion 70 through the relief valve 80. The ejection portion 70 is rotatably arranged in the hydraulic pump 10, and ejects the cooling oil supplied from the hydraulic source toward the friction member that generates frictional heat by sliding with respect to other members (injection step). .. The cooling oil comes into contact with the friction member whose temperature has become high due to the frictional heat and exchanges heat with the friction member, whereby the friction member is cooled.

The hydraulic pump 10 of the present embodiment has a supply / discharge plate 35 having a supply / discharge hole for hydraulic oil, and a plurality of cylinder holes 32 for supplying and discharging hydraulic oil through the supply / discharge plate 35. A cylinder block 30 that rotates while sliding with respect to the supply / discharge plate 35, a piston 38 that is movably provided in each of a plurality of cylinder holes 32, a swash plate 40 that regulates the movement of the piston 38, and a piston 38 and a swash plate. A shoe 43 provided between the shoe 43 and an ejection portion that ejects oil supplied from the hydraulic source 14 toward at least one of a supply / discharge plate 35, a cylinder block 30, a piston 38, a swash plate 40, and a shoe 43. 70 and.

The work machine 1 of the present embodiment includes the above-mentioned hydraulic pump 10.

In the cooling method of the hydraulic pump of the present embodiment, the hydraulic oil is supplied and discharged from the oil supplied from the hydraulic source 14 through the supply / discharge plate 35 having the supply / discharge holes and the discharge holes of the hydraulic oil, and the supply / discharge plate 35. A cylinder block 30 having a plurality of cylinder holes 32 and rotating while sliding with respect to a supply / discharge plate 35, a piston 38 movably provided in each of the plurality of cylinder holes 32, and a swash plate that regulates the movement of the piston 38. It ejects toward at least one of the shoes 43 provided between the 40 and the piston 38 and the swash plate 40.

According to the cooling method of the hydraulic pump 10, the work machine 1, and the hydraulic pump, the friction member (supply / discharge plate 35, cylinder block 30, piston 38) in which the oil ejected from the ejection portion 70 becomes high temperature due to frictional heat. , At least one of the swash plate 40 and the shoe 43) to exchange heat with the friction member (30, 35, 38, 40, 43), thereby exchanging heat with the friction member (30, 35, 38, 40, 43) is cooled. Therefore, the friction member (30, 35, 38, 40, 43) in the hydraulic pump 10 can be efficiently cooled, and the temperature of the oil in contact with the friction member (30, 35, 38, 40, 43) rises. However, it is possible to prevent the viscosity of these oils from decreasing. As a result, the oil film formed between the two members that rub against each other becomes thin, and it becomes possible to reduce the wear or breakage that may occur when the two members come into direct contact with each other and rub against each other.

The hydraulic pump 10 of the present embodiment has a main pump 12 that supplies hydraulic oil to the hydraulic actuator and a pilot pump 14 that supplies pilot oil to the operation unit for workers, and the hydraulic source is the pilot pump 14. is there.

The hydraulic pump 10 of the present embodiment includes a main pump 12 that supplies hydraulic oil to the hydraulic actuator and a piston pump 14 that supplies pilot oil to the operation unit for the operator, and the main pump 12 operates. It has a supply / discharge plate 35 having an oil supply / discharge hole and a plurality of cylinder holes 32 in which hydraulic oil is supplied / discharged through the supply / discharge plate 35, and rotates while sliding with respect to the supply / discharge plate 35. A cylinder block 30, a piston 38 movably provided in each of a plurality of cylinder holes 32, a swash plate 40 that regulates the movement of the piston 38, and a shoe 43 provided between the piston 38 and the slop plate 40. It includes an ejection portion 70 that ejects oil supplied from the pilot pump 14 toward at least one of a supply / discharge plate 35, a cylinder block 30, a piston 38, a swash plate 40, and a shoe 43.

According to such a hydraulic pump 10, a part of the oil discharged from the pilot pump 14 can be stably supplied to the ejection portion 70 as cooling oil.

1 Work machine 10 Hydraulic pump 12 Main pump 14 Pilot pump 16 Rotating shaft 20 Housing 21 1st housing block 22 2nd housing block 23 Guide part 25 Rotating shaft 30 Cylinder block 32 Cylinder hole 34 Side 35 Supply / discharge plate 38 Piston 40 Slanted plate 41 Sliding surface 42 Working surface 43 Shoe 50 1st pressing means 60 2nd pressing means 61 Pressing rod 70 Ejecting part 72 Ejecting hole 80 Relief valve A Rotating axis L Supply line

Claims (5)

A supply / discharge plate having a hydraulic oil supply hole and a discharge hole,
A cylinder block having a plurality of cylinder holes for supplying and discharging the hydraulic oil through the supply / discharge plate and rotating while sliding with respect to the supply / discharge plate.
A piston movablely provided in each of the plurality of cylinder holes,
A swash plate that regulates the movement of the piston,
A shoe provided between the piston and the swash plate,
A hydraulic pump including a discharge portion for ejecting oil supplied from a hydraulic source toward at least one of the supply / discharge plate, the cylinder block, the piston, the swash plate, and the shoe. It has a main pump that supplies hydraulic oil to the hydraulic actuator and a pilot pump that supplies pilot oil to the operation unit for workers.
The hydraulic pump according to claim 1, wherein the hydraulic source is the pilot pump. It has a main pump that supplies hydraulic oil to the hydraulic actuator and a pilot pump that supplies pilot oil to the operation unit for workers.
The main pump
A supply / discharge plate having a hydraulic oil supply hole and a discharge hole,
A cylinder block having a plurality of cylinder holes for supplying and discharging the hydraulic oil through the supply / discharge plate and rotating while sliding with respect to the supply / discharge plate.
A piston movablely provided in each of the plurality of cylinder holes,
A swash plate that regulates the movement of the piston,
A shoe provided between the piston and the swash plate,
A hydraulic pump including a supply / discharge plate, a cylinder block, a piston, a swash plate, and a ejection portion for ejecting oil supplied from the pilot pump toward at least one of the shoes. A work machine provided with the hydraulic pump according to any one of claims 1 to 3. The supply / discharge plate having a supply / discharge plate having a supply hole and a discharge hole for hydraulic oil, and a plurality of cylinder holes for supplying and discharging the hydraulic oil through the supply / discharge plate to supply oil supplied from a hydraulic source. A cylinder block that rotates while sliding, a piston that is movably provided in each of the plurality of cylinder holes, a swash plate that regulates the movement of the piston, and a shoe that is provided between the piston and the swash plate. A method of cooling a hydraulic pump that ejects toward at least one.