JP5912475B2 - Swash plate type hydraulic motor or swash plate type hydraulic pump - Google Patents

Description

  The present invention relates to a swash plate type hydraulic motor or a swash plate type hydraulic pump used in a construction vehicle such as a hydraulic excavator.

  A swash plate type hydraulic motor or a swash plate type hydraulic pump has a tilt piston for changing the tilt angle of the swash plate. Here, for example, in the swash plate hydraulic motor (1) described in Patent Document 1, the swash plate (12) and the tilt control piston (14B) are in point contact.

JP 2004-169654 A

  As described in Patent Document 1, when the swash plate (12) and the tilt control piston (14B) are in point contact, depending on the state of hydraulic pressure supplied to the cylinder, the posture of the swash plate (12) may be changed. May become unstable. For this reason, usually, a shoe that is in surface contact with the swash plate is rotatably attached to the end of the tilt control piston on the swash plate side. Providing the shoe can prevent the swash plate from becoming unstable, but it increases the cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a structure capable of stably holding a swash plate without attaching a shoe to a swash plate side end of a tilt control piston. A swash plate type hydraulic motor or a swash plate type hydraulic pump is provided.

  The present invention for solving the above problems includes a main body case, a rotating shaft housed in the main body case, a cylinder block attached to the rotating shaft, and a plurality of cylinder holes formed in the cylinder block. , A piston slidably inserted into the cylinder hole, a shoe provided at the tip of the piston, a slope on which the shoe slides, and a body formed on the opposite side of the slope with respect to the body case. A swash plate having a support surface supported via a pivot, and abutting the support surface of the swash plate, and tilting the swash plate by pressing the swash plate toward the piston side. In a swash plate type hydraulic motor or swash plate type hydraulic pump comprising a tilting piston and a tilting piston cylinder hole formed in the main body case into which the tilting piston is slidably inserted. A swash plate type hydraulic motor, wherein a swash plate side end surface of a piston is integrally formed with a spherical surface portion, and a concave portion into which the spherical surface portion is slidably fitted is formed on a support surface of the swash plate. Or it is a swash plate type hydraulic pump.

  According to this configuration, the contact range between the tilting piston and the swash plate can be made wider than before without attaching a shoe to the end of the tilting piston on the swash plate side. As a result, it is possible to stably hold the swash plate while reducing the cost as compared with the prior art.

  In the present invention, the bottom surface of the recess is formed in an arc shape having the same shape as the spherical portion in the direction connecting the two pivots, and is perpendicular to the direction connecting the two pivots. Is preferably formed flat.

  According to this configuration, the holding force of the swash plate is improved in the direction connecting the two pivots, and in the direction orthogonal to the direction connecting the two pivots, the spherical portion of the tilting piston and the swash plate The amount of movement of the contact portion is reduced, and wear of the contact portion can be reduced.

  Furthermore, in the present invention, it is preferable that the curvature radius of the bottom surface of the concave portion is larger than the curvature radius of the spherical portion and not more than 1.56 times the curvature radius of the spherical portion.

  According to this configuration, the posture of the swash plate is stabilized, the spherical portion of the tilting piston and the swash plate can be reduced from being in local contact, and wear of the contact portion can be reduced.

  According to the present invention, the spherical portion is integrally formed on the end surface of the tilting piston on the swash plate side, and the concave portion into which the spherical portion is slidably fitted is formed on the support surface of the swash plate. A swash plate type hydraulic motor or swash plate type hydraulic pump having a structure capable of stably holding a swash plate without attaching a shoe to a swash plate side end of a piston (tilting control piston) can be provided.

It is sectional drawing of the swash plate type hydraulic motor which concerns on one Embodiment of this invention. It is a figure of the swash plate which comprises the swash plate type hydraulic motor shown in FIG. FIG. 3 is an AA cross-sectional enlarged view of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. A swash plate type hydraulic motor 1 (swash plate type hydraulic rotating machine) described below is used for a traveling device in a construction vehicle such as a hydraulic excavator, and has a variable capacity capable of switching between a high speed and a low speed. Type hydraulic motor. The present invention can be applied not only to a swash plate type hydraulic motor but also to a swash plate type hydraulic pump.

(Configuration of swash plate hydraulic motor)
FIG. 1 is a sectional view of a hydraulic motor 1 according to an embodiment of the present invention, and FIG. 2 is a view of a swash plate 7 constituting the hydraulic motor 1. FIG. 2A is a front view of the swash plate 7, and FIG. 2B is a side sectional view of the swash plate 7.

  As shown in FIG. 1, the hydraulic motor 1 includes a main body case 2, a rotating shaft 3, a cylinder block 4, a piston 5, a shoe 6, a swash plate 7, a tilting piston 8, and the like.

(Main unit case and rotating shaft)
The main body case 2 is for housing the rotary shaft 3, the cylinder block 4, the piston 5, the swash plate 7 and the like, and the rotary shaft 3 is held rotatably with respect to the main body case 2.

(Cylinder block)
The cylinder block 4 is spline-coupled to the rotating shaft 3 and is attached to the rotating shaft 3 so as to be movable in the axial direction X of the rotating shaft 3 and to rotate together with the rotating shaft 3 in the rotating direction of the rotating shaft 3. ing. A plurality of cylinder holes 4 a are formed in the axial direction around the axis of the cylinder block 4. These cylinder holes 4a are arranged at equal intervals on the same circumference. The cylinder hole 4 a is formed in the cylinder block 4 so that its longitudinal direction is parallel to the axial direction X.

(Piston and shoe)
Plural pistons 5 are provided, and are inserted into the cylinder holes 4a so as to be slidable with respect to the inner wall surface of the cylinder hole 4a. A shoe 6 is attached to a sphere formed at the tip of the piston 5.

(Swash plate)
As shown in FIGS. 1 and 2, the swash plate 7 has a slope 7 a on which the shoe 6 slides, and a support surface 7 b that is formed on the opposite side of the slope 7 a and is supported with respect to the main body case 2. The swash plate 7 is formed in an annular shape when viewed from the axial direction X, and the rotating shaft 3 passes through the hole 7c.

  When pressure oil is supplied to or discharged from each cylinder hole 4a of the cylinder block 4, the piston 5 inserted into each cylinder hole 4a reciprocates. As the piston 5 reciprocates, the shoe 6 rotates while sliding on the inclined surface 7a of the swash plate 7, and the piston 5 also rotates. The cylinder block 4 is rotated by the rotation of the piston 5, and the rotating shaft 3 is rotated integrally with the cylinder block 4.

  The support surface 7b of the swash plate 7 includes a first support surface 7b1 and a second support surface 7b2 which are two surfaces having different angles with respect to the axial direction X of the rotating shaft 3. Pivots 11 are slidably disposed on the support surface 7b of the swash plate 7 on the intersecting line L1 where the first support surface 7b1 and the second support surface 7b2 intersect and on both sides of the rotating shaft 3. . These two pivots 11 are fixed to the main body case 2. The swash plate 7 swings around two pivots 11 between a position where the first support surface 7b1 contacts the body case 2 and a position where the second support surface 7b2 contacts the body case 2 (see FIG. 1). It comes to move.

  Note that the pivot 11 is slidably disposed in each of the two pivot holes 7d shown in FIG. The two pivots 11 (pivot hole 7d) are arranged symmetrically with respect to a center line L2 passing through the center of the rotation shaft 3.

(Tilt piston)
On the inner wall surface of the main body case 2 where the second support surface 7b2 of the swash plate 7 abuts against the main body case 2, there is provided a tilt piston cylinder hole 9 having a circular cross section into which the tilt piston 8 is slidably inserted. It has been. A tilting piston 8 that tilts (swings) the swash plate 7 by inserting the swash plate 7 toward the piston 5 is inserted into the tilting piston cylinder hole 9.

  Here, FIG. 3 is an AA cross-sectional enlarged view of FIG. 2A, and also shows the tilting piston 8 that contacts the second support surface 7 b 2 of the swash plate 7. As shown in FIGS. 1 and 3, the tilting piston 8 is partially cylindrical and has a main body 8 a that slides on the inner wall surface of the tilting piston cylinder hole 9, and a main body on the swash plate 7 side. 8a has a spherical surface portion 8b formed integrally with the main body portion 8a. Note that the term “integrally formed” means that the tilting piston 8 having the main body portion 8a and the spherical surface portion 8b is manufactured from one material (steel material) by casting forging or cutting. This means that the main body portion 8a and the spherical surface portion 8b are not separately manufactured parts.

  As shown in FIG. 1, a back pressure chamber 13 into which pressure oil for operating the tilting piston 8 is introduced is formed between the tilting piston 8 and the bottom surface of the tilting piston cylinder hole 9. . In addition, the pressure oil to the back pressure chamber 13 for operating the tilting piston 8 is supplied through an oil passage 14 provided in the main body case 2. A spring 12 (coil spring) is disposed in the back pressure chamber 13 (tilting piston cylinder hole 9). The tilting piston 8 is always urged toward the swash plate 7 by the spring 12 and is in contact (contact) with the second support surface 7 b 2 of the swash plate 7. The tilting piston 8 presses the swash plate 7 toward the piston 5 side by switching a switching valve (not shown) and supplying pressure oil to the back pressure chamber 13 through the oil passage 14. ing. As a result, the tilt angle of the swash plate 7 changes and the hydraulic motor 1 switches from low speed to high speed. When the supply of pressure oil to the back pressure chamber 13 is stopped, the oil escapes from the back pressure chamber 13 and the tilting piston 8 moves backward, and the tilting angle of the swash plate 7 changes to switch the hydraulic motor 1 from high speed to low speed. Change. FIG. 1 is a view when the swash plate is at a low speed position.

(Concave groove formed on the support surface of the swash plate)
As shown in FIGS. 2 and 3 with reference numerals, the second support surface 7b2 of the swash plate 7 is formed with a concave groove 10 into which the spherical portion 8b of the tilting piston 8 is slidably fitted. .

  The concave groove 10 is a part of the second support surface 7 b 2, and is a groove-shaped concave part having a predetermined width having a longitudinal direction in a direction orthogonal to a direction connecting the two pivots 11. The concave groove 10 is formed with a predetermined width on the second support surface 7b2 of the swash plate 7 from the center of the rotation shaft 3 toward the outer periphery of the swash plate 7, from the hole 7c of the swash plate 7 to the outer periphery of the swash plate 7. ing. The bottom surface of the concave groove 10 is formed in an arc shape having the same shape as the spherical surface portion 8b of the tilting piston 8 in the direction connecting the two pivots 11 (see FIG. 3). It is formed flat (flat) in the direction orthogonal to the direction of tying (see FIG. 2).

(Action / Effect)
In the hydraulic motor 1 of the present embodiment, the contact area between the swash plate 7 and the tilting piston 8 is increased as compared with the hydraulic motor described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-169654). As a result, the posture of the swash plate 7 that swings around the two pivots 11 is stabilized. That is, the swash plate 7 can be stably held. Since it is not necessary to attach a shoe in surface contact with the swash plate 7 to the end of the tilting piston 8 on the swash plate side, the swash plate 7 can be stably held while reducing costs.

  Further, since the contact area between the swash plate 7 and the tilting piston 8 is increased, the wear resistance of the swash plate 7 is improved. As a result, the necessity of performing a curing process such as a heat treatment on the swash plate 7 is reduced. Cost can be reduced also from this viewpoint. Further, the wear of the swash plate can be reduced only by adding simple components such as the tilting piston 8 integrally formed with the spherical surface portion 8b and the swash plate 7 formed with the concave groove 10.

  Further, by forming the concave portion formed on the support surface of the swash plate 7 as the concave groove 10 as in the present embodiment, the holding force of the swash plate 7 is improved in the direction connecting the two pivots 11, and two pieces are provided. In the direction perpendicular to the direction connecting the pivots 11 (the direction in which the center line L2 extends), the amount of movement of the contact portion between the spherical portion 8b of the tilting piston 8 and the swash plate 7 is reduced, and the contact portion Wear can be reduced.

  The concave portion formed in the second support surface 7b2 of the swash plate 7 and into which the spherical portion 8b of the tilting piston 8 is fitted is not a groove shape having a predetermined width (concave groove 10), but has the same shape as the spherical portion 8b. It may be spherical.

(Relationship between the radius of curvature of the bottom of the groove and the radius of curvature of the spherical surface of the tilting piston)
The curvature radius R of the bottom surface of the concave groove 10 is preferably larger than the curvature radius r of the spherical surface portion 8b of the tilting piston 8 and not more than 1.56 times the curvature radius r of the spherical surface portion 8b. Specifically, for example, if the radius of curvature r of the spherical portion 8b of the tilting piston 8 is 24.5 mm (φ49 mm in terms of a spherical diameter), the radius of curvature R of the bottom surface of the concave groove 10 is 25 mm (of the spherical portion 8b). The curvature radius r is preferably 1.02 times or more and 38 mm or less (in terms of diameter, 50 mm or more and 76 mm or less).

  Thereby, while the attitude | position of the swash plate 7 is stabilized, it can reduce that the spherical surface part 8b of the inclination piston 8 and the swash plate 7 contact locally, As a result, abrasion of these contact parts can be reduced. Note that the bottom surface of the groove 10 has an arc shape means that the radius of curvature R of the bottom surface of the groove 10 is constant over the entire width direction of the groove 10 (the direction connecting the two pivots 11). It is. Further, regarding the tilting piston 8, the fact that the end surface on the swash plate side is the spherical surface portion 8b means that the radius of curvature r of the end surface on the swash plate side is constant over the entire end surface on the swash plate side.

  Moreover, it is more preferable that the curvature radius R of the bottom surface of the concave groove 10 is 1.3 times or more and 1.56 times or less of the curvature radius r of the spherical surface portion 8b. For example, if the radius of curvature r of the spherical portion 8b is 24.5 mm (φ49 mm in terms of spherical diameter), the radius of curvature R of the bottom surface of the concave groove 10 is 32 mm or more and 38 mm or less (64 mm or more and 76 mm or less in terms of diameter). It is preferable that

  Thereby, even when the machining error of the shape of the pivot 11 is somewhat large, it is possible to avoid the spherical portion 8b of the tilting piston 8 from hitting the corners of the concave groove 10 (both ends in the width direction of the concave groove 10). Can do.

  Furthermore, the radius of curvature R of the bottom surface of the concave groove 10 is larger than the radius of curvature r of the spherical surface portion 8b of the tilting piston 8 and 1.56 times or less of the radius of curvature r of the spherical surface portion 8b. When the radius of curvature r of 8b is 1.3 times or more and 1.56 times or less, the radius of curvature r of the spherical portion 8b is 24.5 mm (φ49 mm in terms of sphere diameter) or more and 30 mm (sphere diameter). In other words, it is preferable that the diameter is 60 mm or less.

  As a result, the amount of movement of the contact portion between the spherical portion 8b of the tilting piston 8 and the swash plate 7 is reduced, and the lateral load acting on the tilting piston 8 can be reduced. As a result, an increase in the surface pressure acting on the inner surface of the tilting piston cylinder hole 9 formed in the main body case 2 is reduced, and wear of the tilting piston cylinder hole 9 is reduced.

1: Hydraulic motor (swash plate type hydraulic motor)
2: Body case 3: Rotating shaft 4: Cylinder block 5: Piston 6: Shoe 7: Swash plate 7b: Support surface 7b1: First support surface 7b2: Second support surface 8: Tilt piston 8b: Spherical surface portion 9: Tilt Cylinder hole 10 for rolling piston: concave groove (concave)

Claims (2)

A body case,
A rotating shaft housed in the body case;
A cylinder block attached to the rotating shaft;
A plurality of cylinder holes formed in the cylinder block;
A piston slidably inserted into the cylinder hole;
A shoe provided at the tip of the piston;
A swash plate having a slope on which the shoe slides and a support surface formed on the opposite side of the slope and supported by two pivots with respect to the main body case;
A tilting piston that abuts the support surface of the swash plate and tilts the swash plate by pressing the swash plate toward the piston;
A cylinder hole for a tilting piston that is formed in the main body case and into which the tilting piston is slidably inserted;
In a swash plate type hydraulic motor or swash plate type hydraulic pump comprising:
A spherical portion is integrally formed on the end surface of the tilting piston on the swash plate side,
A concave portion is formed on the support surface of the swash plate so that the spherical portion is slidably fitted ,
The bottom surface of the recess is
In the direction connecting the two pivots, it is formed in an arc shape having the same shape as the spherical portion,
A swash plate type hydraulic motor or a swash plate type hydraulic pump, wherein the swash plate type hydraulic motor or swash plate type hydraulic pump is formed flat in a direction perpendicular to a direction connecting the two pivots . In the swash plate type hydraulic motor or swash plate type hydraulic pump according to claim 1 ,
A swash plate type hydraulic motor or a swash plate type characterized in that the radius of curvature of the bottom surface of the concave portion is larger than the radius of curvature of the spherical portion and not more than 1.56 times the radius of curvature of the spherical portion. Hydraulic pump.

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