JP2016023567A - Variable displacement piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable displacement piston pump for allowing a selective change in the inclination of a swash plate without using a thin-plate swash plate support.SOLUTION: A variable displacement piston pump 1 includes a pump housing 2 for rotatably supporting a rotating shaft 3, and a cylinder block 9 and a swash plate 10 stored in the pump housing 2. A sliding member 19 is fixed to the swash plate 10 at the counter-side end of its face on the side opposite to the cylinder block 9, and has a cross-section circular convex sliding surface 22 for sliding relatively to a front housing 4 of the pump housing 2. On the front housing 4, a cross-section circular concave receiving surface 25 is provided to be fitted to the convex sliding surface of the sliding member 19. The concave receiving surface 25 slidably holds the convex sliding surface 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a variable displacement piston pump including a swash plate.

  As a conventional variable displacement piston pump, for example, a technique described in Patent Document 1 is known. The variable displacement piston pump described in Patent Document 1 includes a rotating shaft that is rotatably supported between end walls of a pair of housings, a cylinder block that rotates integrally with the rotating shaft, A plurality of pistons slidably displaceable and a swash plate for adjusting the strokes of these pistons are provided. A pair of swash plate holders that are in sliding contact with the swash plate are attached to the arcuate surface of the pair of swash plate guides provided in the housing.

JP 2008-82235 A

  In the above prior art, the inclination angle of the swash plate changes as the swash plate slides relative to the swash plate support. The swash plate receiver made of a thin plate is processed to have a curved cross section so as to correspond to the support surface having a curved cross section of the swash plate guide. However, the thin plate-shaped swash plate receiver has a problem that unintentional deformation is likely to occur during processing to make the cross-sectional curve shape and mounting to a swash plate guide. Unintentional deformation of the swash plate receiver is not preferable because it causes backlash when the swash plate slides. In addition, if the swash plate receiver is a thin plate, it is difficult to use a screw or the like for attachment to the swash plate guide. Therefore, special processing such as forming a convex portion on the swash plate receiver as in the above-described prior art. It was necessary.

  An object of the present invention is to provide a variable displacement piston pump capable of arbitrarily changing the inclination angle of a swash plate without using a thin swash plate receiver.

  The present invention relates to a cylinder block in a variable displacement piston pump that sucks and discharges a working fluid by reciprocating a piston in a cylinder block that rotates integrally with a rotating shaft with a stroke corresponding to an inclination angle of a swash plate. And a housing that accommodates the swash plate and rotatably supports the rotation shaft, and a block shape having a convex sliding surface with an arc-shaped cross section fixed to the opposite side of the surface of the swash plate facing the cylinder block And a swash plate guide portion that is provided in the housing and slidably supports the sliding member so that the inclination angle of the swash plate can be changed. A concave receiving surface having an arc-shaped cross section to be fitted to the mold sliding surface is formed, and the sliding member is formed of a material having a better sliding property than the material constituting the swash plate guide portion. Features.

  As described above, in the variable displacement piston pump of the present invention, the block-shaped sliding member is fixed to the opposite side of the surface of the swash plate facing the cylinder block, and the cross-section of the sliding member has an arc shape. The inclination angle of the swash plate is changed by sliding the convex sliding surface with respect to the concave receiving surface having an arcuate cross section in the swash plate guide portion provided in the housing. Thus, the inclination angle of the swash plate can be arbitrarily changed without using a thin swash plate receiver. At this time, the sliding member is formed of a material having better sliding properties than the material constituting the swash plate guide portion. Therefore, the sliding member slides smoothly with respect to the swash plate guide portion.

  A flat fixed surface is provided on the opposite side of the surface of the swash plate facing the cylinder block, and the sliding member has a flat fixed surface that engages with the fixed surface. May be. In this case, since the flat fixed surface of the swash plate and the flat fixing surface of the sliding member are fixed in contact with each other, rattling between the swash plate and the sliding member can be suppressed. it can.

  The shape of the sliding member may be substantially semicircular in cross section. In this case, for example, a sliding member having a substantially semicircular cross section can be easily manufactured by cutting a round bar and polishing the cut surface.

  The sliding member may be formed of a copper-based sliding material. Copper-based sliding materials have good slidability and are inexpensive.

  According to the present invention, the inclination angle of the swash plate can be changed without attaching a member for receiving the swash plate to the housing.

1 is a schematic cross-sectional view showing an embodiment of a variable displacement piston pump according to the present invention. It is sectional drawing which shows the fixed state of the swash plate and sliding member which were shown by FIG. It is the front view which looked at the swash plate and sliding member shown by FIG. 2 from the front housing side.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic sectional view showing an embodiment of a variable displacement piston pump according to the present invention. In the figure, a variable displacement piston pump 1 of this embodiment is used as a hydraulic pump mounted on, for example, an engine-type forklift.

  The variable displacement piston pump 1 includes a pump housing 2 and a rotating shaft 3 that is rotatably supported by the pump housing 2. The rotating shaft 3 is rotationally driven by an engine (not shown).

  The pump housing 2 includes a front housing 4, a center housing 5 and a rear housing 6. The pump housing 2 is made of an iron-based material such as cast iron. In the present embodiment, the axial direction of the rotary shaft 3 is defined as the front-rear direction of the variable displacement piston pump 1. The front housing 4 side is the front side of the variable displacement piston pump 1, and the rear housing 6 side is the rear side of the variable displacement piston pump 1. A front end side portion of the rotary shaft 3 protrudes from the pump housing 2.

  The rear housing 6 is formed with a suction passage 7 for sucking hydraulic oil and a discharge passage 8 for discharging hydraulic oil.

  A cylinder block 9 and a swash plate 10 are accommodated in the pump housing 2. The swash plate 10 is disposed on the front side (front housing 4 side) of the cylinder block 9.

  The cylinder block 9 is spline-fitted to the rotary shaft 3 so as to be integrally rotatable. A plurality of cylinder bores 11 are formed around the rotary shaft 3 in the cylinder block 9. A piston 12 is slidably accommodated in each cylinder bore 11. Although not shown, a spring that biases the swash plate 10 is disposed between the cylinder block 9 and the rotary shaft 3.

  A valve plate 13 is disposed between the cylinder block 9 and the rear housing 6. The valve plate 13 is fixed to the rear housing 6. The valve plate 13 is formed with a suction hole 14 for communicating the suction passage 7 and the cylinder bore 11 and a discharge hole 15 for communicating the discharge passage 8 and the cylinder bore 11. As a result, the hydraulic oil is sucked into the cylinder bore 11 from the suction hole 14 and the hydraulic oil in the cylinder bore 11 is discharged from the discharge hole 15.

  The swash plate 10 is formed with a through hole 10a that allows the rotation shaft 3 to pass therethrough. As shown in FIGS. 2 and 3, two fixed surfaces 16 sandwich the through hole 10 a at the front end of the swash plate 10 (the portion on the opposite side of the surface facing the cylinder block 9). Is provided. The fixed surface 16 has a planar shape. An annular sliding contact surface 17 is provided at the rear end of the swash plate 10 (portion facing the cylinder block 9). The sliding surface 17 has a planar shape.

  The swash plate 10 is made of an iron-based material such as chrome molybdenum steel. Chromium molybdenum steel is a kind of low alloy steel obtained by adding a slight amount of chromium, molybdenum and the like to iron.

  The swash plate 10 is formed with two screw holes 18 opened in each fixed surface 16. A sliding member 19 having a substantially semicircular cross section (block shape) is fixed to each fixed surface 16 by a fixing screw 20. In other words, the two sliding members 19 are fixed to the swash plate 10 so as to sandwich the rotating shaft 3.

  The sliding member 19 has a flat fixed surface 21 that engages with the fixed surface 16 of the swash plate 10, and a convex sliding surface 22 that has an arcuate cross section that slides relative to the front housing 4. . The fixed surface 21 extends straight from one end of the convex sliding surface 22 to the other end.

  The sliding member 19 is formed with a screw accommodating recess 23 in which the fixing screw 20 is accommodated. The screw housing recess 23 is open to the convex sliding surface 22. In addition, an insertion hole 24 that is in communication with the screw housing recess 23 and through which the fixing screw 20 is inserted is formed in a region of the sliding member 19 on the fixed surface 21 side. The fixing screw 20 is inserted into the screw receiving recess 23 and screwed into the screw hole 18 of the swash plate 10 through the insertion hole 24, so that the fixing surface 21 of the sliding member 19 and the fixed surface 16 of the swash plate 10 come into contact with each other. In this state, the sliding member 19 is fixed to the swash plate 10.

  The sliding member 19 is formed of a copper-based sliding material that is slidable and excellent in wear resistance with respect to the iron-based material that is the material of the front housing 4, for example, a copper alloy such as bronze and brass. . The sliding member 19 is obtained, for example, by cutting a round bar made of such a metal material and polishing the cut surface.

  The front housing 4 is provided with a concave receiving surface 25 that fits with the convex sliding surface 22 of the sliding member 19. The concave receiving surface 25 has a circular arc shape corresponding to the shape of the convex sliding surface 22. The concave receiving surface 25 receives the thrust force of the swash plate 10 and slidably holds the convex sliding surface 22 of the sliding member 19. Thereby, the inclination angle of the swash plate 10 can be changed. In the present embodiment, the region of the concave receiving surface 25 of the front housing 4 also serves as a swash plate guide portion that slidably supports the sliding member 19 so that the inclination angle of the swash plate 10 can be changed.

  A plurality of shoes 26 are in close contact with the sliding contact surface 17 of the swash plate 10. Each shoe 26 is fitted with the tip of the piston 12 in the cylinder block 9. Each shoe 26 is attached to one annular retainer plate 27. A pivot 28 fixed to the retainer plate 27 is disposed around the rotary shaft 3 on the front side (swash plate 10 side) of the cylinder block 9. The pivot 28 is pushed to the front side via a pin (not shown) by the aforementioned spring (not shown). As a result, the retainer plate 27 is pushed forward, and accordingly, the shoes 26 are sufficiently brought into close contact with the sliding contact surface 17 of the swash plate 10. Each piston 12 is reciprocated at a stroke corresponding to the inclination angle of the swash plate 10 as the cylinder block 9 rotates.

  A recessed portion 10 b that opens to the rear side of the swash plate 10 is formed at a predetermined position of the edge of the swash plate 10. A roller 29 is accommodated in the recess 10b. Between the front housing 4 and the portion of the swash plate 10 on the concave portion 10b side in the pump housing 2, a spring (not shown) for urging the concave portion 10b side of the swash plate 10 toward the cylinder block 9 is disposed. Has been.

  The variable displacement piston pump 1 includes a control piston unit 30 that controls the discharge amount of the variable displacement piston pump 1 by controlling the inclination angle of the swash plate 10. The control piston unit 30 is provided adjacent to the cylinder block 9 on the roller 29 side. The control piston unit 30 has a substantially cylindrical unit wall portion 31 that constitutes a part of the center housing 5. The unit wall 31 extends in a direction inclined with respect to the rotation shaft 3.

  A screw portion 32 that closes the opening of the unit wall portion 31 is provided at the rear end portion (end portion on the rear housing 6 side) of the unit wall portion 31. A control piston 33 that presses the swash plate 10 is disposed in the unit wall 31. The hydraulic oil flows between the control piston 33 and the screw portion 32 in the unit wall portion 31. The front end of the control piston 33 is in contact with the roller 29.

  When the swash plate 10 presses the control piston 33 via the roller 29 by the urging force of the spring (not shown), the swash plate 10 has the maximum inclination angle, and the discharge amount of the variable displacement piston pump 1 becomes the maximum amount. . When hydraulic oil flows between the control piston 33 and the screw portion 32 in the unit wall 31, the control piston 33 resists the urging force of a spring (not shown) and the swash plate 10 through the roller 29. Press. Thereby, the inclination | tilt angle of the swash plate 10 becomes small, and the discharge amount of the variable displacement piston pump 1 reduces. In the idling state of the engine where there is no cargo handling request, the swash plate 10 has the minimum inclination angle, and the discharge amount of the variable displacement piston pump 1 becomes the minimum amount.

  As described above, in the present embodiment, the convex sliding surface 22 having an arc-shaped cross section that slides with respect to the front housing 4 is provided on the opposite side of the surface facing the cylinder block 9 in the swash plate 10. The block-shaped sliding member 19 is fixed, and the front housing 4 is provided with a concave receiving surface 25 having an arc-shaped cross section that fits with the convex sliding surface 22 of the sliding member 19. In such a configuration, the swash plate 10 changes its angle between the minimum inclination angle and the maximum inclination angle by sliding the convex sliding surface 22 of the sliding member 19 with respect to the concave receiving surface 25 of the front housing 4. To do. For this reason, the inclination angle of the swash plate 10 can be arbitrarily set without attaching a thin plate-like sliding member such as a thrust bush for slidably supporting the swash plate 10 to the swash plate guide of the front housing 4 as in the prior art. Can be changed. Further, since the sliding member 19 is made of a material having better sliding properties than the material constituting the front housing 4 (swash plate guide portion), the swash plate 10 is smoothly slid when the inclination angle of the swash plate 10 is changed. Can be moved. Therefore, the occurrence of seizure between the swash plate 10 and the front housing 4 can be prevented.

  When a thin plate-like sliding member such as a thrust bush for slidably supporting the swash plate 10 is attached to the swash plate guide of the front housing 4, the curved surface is processed and attached to the swash plate guide. There is a problem that the thin plate-like sliding member is easily deformed at times. In the present embodiment, since the block-shaped sliding member 19 having a semicircular cross section is directly attached and fixed to the swash plate 10, such a problem does not occur. As a result, rattling of the swash plate 10 can be prevented.

  In addition, a flat fixed surface 16 is provided on the opposite end of the cylinder block 9 in the swash plate 10, and a flat fixed surface that engages the fixed surface 16 of the swash plate 10 on the sliding member 19. 21 is provided, the sliding member 19 is fixed to the swash plate 10 in a state where the fixing surface 21 and the fixed surface 16 are in close contact with each other. Therefore, rattling between the swash plate 10 and the sliding member 19 can be suppressed.

  Furthermore, since the shape of the sliding member 19 is substantially semicircular in cross section, the sliding member 19 can be easily manufactured by cutting a round bar, for example. Therefore, it becomes easy to process the sliding member 19, and the processing time of the sliding member 19 can be shortened.

  Moreover, since the thickness of the sliding member 19 is ensured, the sliding member 19 and the swash plate 10 can be reliably fixed by the fixing screw 20.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the shape of the sliding member 19 is a substantially semicircular cross section having the fixed surface 21 and the convex sliding surface 22, but the shape of the sliding member 19 is not particularly limited thereto, It is only necessary to have a convex sliding surface 22 having an arcuate cross section that fits into a concave receiving surface 25 having an arcuate cross section provided in the front housing 4. For example, the sliding member 19 may have a fixed surface extending in a concavo-convex shape from one end side to the other end side of the convex sliding surface 22.

  Moreover, in the said embodiment, although the sliding member 19 is formed with the copper alloy, as a material which forms the sliding member 19, besides metals, such as copper, gold | metal | money, silver, or aluminum, Alternatively, materials having good sliding properties such as alloys thereof can be used. Moreover, as a material which forms the sliding member 19, you may form with carbon steel etc., and may form from several materials.

  Further, in the above-described embodiment, the area of the concave receiving surface 25 of the front housing 4 also serves as a swash plate guide portion that slidably supports the sliding member 19, but the swash plate guide portion is separated from the front housing 4. It may be formed. In this case, two swash plate guides having concave receiving surfaces having an arcuate cross section are attached to the front housing 4.

  Further, in the above embodiment, the sliding member 19 and the swash plate 10 are fixed by the fixing screw 20, but the fixing method of the sliding member 19 and the swash plate 10 is not particularly limited to the screw, and may be by welding or the like. There may be.

  Further, in the above embodiment, the two sliding members 19 are fixed to the swash plate 10 so as to sandwich the rotating shaft 3, but the number of the sliding members 19 is not particularly limited to two, but one However, it may be three or more.

  Furthermore, although the said embodiment is the variable displacement type piston pump 1 which carries out the suction | inhalation and discharge of hydraulic fluid, this invention is applicable also to the variable displacement type piston pump which uses liquids other than oil as a working fluid. .

DESCRIPTION OF SYMBOLS 1 ... Variable displacement type piston pump, 2 ... Pump housing, 3 ... Rotating shaft, 4 ... Front housing (swash plate guide part), 9 ... Cylinder block, 10 ... Swash plate, 12 ... Piston, 16 ... Fixed surface, 19 ... Sliding member, 21 ... fixed surface, 22 ... convex sliding surface, 25 ... concave receiving surface.

Claims (4)

In the variable displacement piston pump that sucks and discharges the working fluid by reciprocating the piston in the cylinder block that rotates integrally with the rotating shaft with a stroke corresponding to the inclination angle of the swash plate,
A housing that houses the cylinder block and the swash plate and rotatably supports the rotating shaft;
A block-like sliding member fixed on the opposite side of the surface of the swash plate facing the cylinder block, and having a convex sliding surface having a circular arc cross section;
A swash plate guide portion that is provided in the housing and slidably supports the sliding member so that an inclination angle of the swash plate can be changed;
The swash plate guide portion is formed with a concave receiving surface having an arc-shaped cross section that fits with the convex sliding surface of the sliding member,
The variable displacement piston pump, wherein the sliding member is made of a material having a better sliding property than a material constituting the swash plate guide portion. On the opposite side of the surface of the swash plate facing the cylinder block, a flat fixed surface is provided,
The variable displacement piston pump according to claim 1, wherein the sliding member has a flat fixed surface that engages with the fixed surface.   The variable displacement piston pump according to claim 1 or 2, wherein the sliding member has a substantially semicircular cross section. The variable displacement piston pump according to any one of claims 1 to 3, wherein the sliding member is made of a copper-based sliding material.

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