JP7186606B2 - Swash plate hydraulic rotary machine - Google Patents

Description

The present invention relates to a swash plate type hydraulic rotary machine used as a hydraulic pump or hydraulic motor in construction machines such as hydraulic excavators, hydraulic cranes, and wheel loaders, and in particular, improves reliability and extends service life when used as a hydraulic pump. It relates to a swash plate type hydraulic rotary machine that contributes to the

In general, a swash plate type hydraulic rotary machine widely used as a hydraulic motor or a hydraulic pump mounted on construction machinery such as a hydraulic excavator includes a casing, a rotating shaft provided rotatably in the casing, and the rotating shaft. a cylinder block provided in the casing so as to rotate integrally with the casing and formed with a plurality of cylinders spaced apart in the circumferential direction and extending in the axial direction; a plurality of pistons projecting from the cylinder at one end in the axial direction; a swash plate provided in the casing facing the cylinder block and having a sliding surface on which the piston shoes slide on the surface facing the cylinder block; and projections of the piston shoes and the pistons. An annular flat plate made of ferrous material and having a plurality of through-holes positioned between the end of the swash plate and inserted through the rotating shaft and through which the respective piston shoes are inserted and pressed against the sliding surface of the swash plate. and a hemispherical retainer made of ferrous material, which is located between the retainer and the cylinder block, is inserted into the rotating shaft, and presses the retainer toward the swash plate with its outer peripheral surface. and retainer guides. In the swash plate type hydraulic rotary machine, a valve plate having high pressure ports and low pressure ports alternately communicating with a plurality of cylinders of a cylinder block is fixed to a casing, and the valve plate and the cylinder block are mutually connected. The sliding surface has a seal land structure that suppresses leakage of hydraulic oil from the high-pressure port and the low-pressure port (see, for example, Patent Document 1 below).

In this type of swash plate hydraulic rotary machine, a piston shoe is swingably attached to a piston through a spherical joint formed on the piston shoe (see Patent Document 1), or a spherical surface formed on the piston There is one in which a piston shoe is swingably attached to a piston via a joint (see Patent Document 2).

The swash plate type hydraulic rotary machine can be used as a hydraulic pump that supplies hydraulic oil to a hydraulic cylinder or the like, or as a hydraulic motor that is rotationally driven by the supplied hydraulic oil. When used as a hydraulic pump, the swash plate is arranged in an inclined state with respect to the rotary shaft as described in Patent Documents 1 and 2, and high-pressure hydraulic oil is supplied as the piston reciprocates within the cylinder due to the rotation of the rotary shaft. to dispense. Here, construction machinery generally employs a system in which a plurality of actuators and hydraulic motors are connected to a single hydraulic pump. However, in recent years, a system has been proposed in which one hydraulic pump is connected to one main actuator for the purpose of high efficiency and detailed control of each hydraulic motor and actuator. Hydraulic pumps used in such systems should tilt the swash plate when operating the actuator, and set the swash plate horizontally (perpendicular to the axis of rotation) when stopping the actuator. , the discharge of high-pressure hydraulic oil due to the reciprocating motion of the piston in the cylinder is stopped.

JP 2011-32883 A JP-A-11-82290

However, the conventional swash plate type hydraulic rotary machine described above has the following problems.

That is, when the swash plate is tilted, the shoes slide on the swash plate while being sandwiched between the swash plate and the retainer. The piston receives reaction force when discharging high-pressure hydraulic oil, and the shoe is pressed against the swash plate with excessive force. For this reason, in order to prevent the shoes from seizing, the sliding surface of the shoes with the swash plate is generally designed to have a hydrostatic bearing structure so that there is no solid contact between the shoes and the swash plate. and the frictional force between the swash plate becomes smaller. On the other hand, the shoe is also pressed against the swash plate by a retainer supported by a spring, ensuring stability during operation. This spring force is very small compared to the reaction force from the piston when hydraulic fluid is discharged, but since it is not a hydrostatic bearing structure, the retainer and shoe are in solid contact when used. Therefore, the friction between the shoe and the retainer is greater than the friction between the shoe and the swash plate, and the retainer suppresses the force of the swash plate that tends to rotate the shoe. When the swash plate is tilted, the piston, which is connected to the shoe via the spherical joint, slides on the shoe at the spherical joint (also known as rolling motion), and this friction force causes the piston to rotate inside the cylinder. while the cylinder block rotates inside the casing. As the piston rotates inside the cylinder, it always comes into contact with (the inner peripheral surface of) the cylinder at different positions, so the structure is such that seizure is less likely to occur.

However, when the swashplate is horizontal, little sliding occurs at the spherical joint between the piston and shoe. For this reason, the piston does not rotate inside the cylinder, so the piston (outer peripheral surface) remains in contact with the cylinder (inner peripheral surface) at the same position. I have concerns.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable swash plate type hydraulic rotary machine.

In order to solve the above problems, a swash plate hydraulic rotary machine according to the present invention includes a casing, a rotating shaft rotatably provided in the casing, and a rotating shaft in the casing so as to rotate integrally with the rotating shaft. a cylinder block formed with a plurality of cylinders spaced apart in the circumferential direction and extending in the axial direction; A plurality of pistons, a shoe attached to the projecting end of each piston, and a sliding surface provided in the casing facing the cylinder block on which the shoes slide on the surface facing the cylinder block. a formed swash plate, retainers positioned between the shoes and the protruding ends of the pistons to bring the shoes into contact with the sliding surfaces of the swash plate, the retainer and the cylinder block. and a retainer guide positioned between and pressing the retainer toward the swash plate with its outer peripheral surface, the contact surface between the retainer and the shoe. A friction-reducing member is installed on at least one side as friction-reducing processing , and the surface of the member has a convex surface that increases in inclination with respect to the contact surface as the distance from the shoe increases . A swash plate hydraulic rotary machine according to the present invention includes a casing, a rotating shaft rotatably provided in the casing, and a rotating shaft provided in the casing so as to rotate integrally with the rotating shaft. a cylinder block formed with a plurality of spaced apart cylinders extending in the axial direction; a plurality of pistons which are reciprocally inserted into the respective cylinders of the cylinder block and protrude from the cylinders at one end in the axial direction; a shoe attached to the protruding end of each piston; and a swash plate provided in the casing facing the cylinder block and having a sliding surface on which the shoes slide on the surface facing the cylinder block. , a retainer positioned between each shoe and the projecting end of each piston to bring each shoe into contact with the sliding surface of the swash plate; and a retainer positioned between the retainer and the cylinder block. A swash plate type hydraulic rotary machine comprising a retainer guide that presses the retainer toward the swash plate with an outer peripheral surface, wherein at least one contact surface between the retainer and the shoe has friction. The reducing treatment includes a friction-reducing texture that reduces rolling friction about the shoe in one direction more than rolling friction in the other direction.

The present invention can provide a highly reliable swash plate type hydraulic rotary machine by providing the above configuration.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows one Embodiment of the swash-plate-type hydraulic rotary machine of this invention. It is the schematic of the contact part of a shoe and a retainer in a swash-plate-type hydraulic rotary machine shown in FIG. 1, (a) is a perspective view, (b) is a side view. (a) to (c) are cross-sectional views of contact portions between the shoe and the retainer in the first embodiment. (a) to (c) are cross-sectional views of contact portions between the shoe and the retainer in the second embodiment. (a) to (c) are cross-sectional views of the contact portion between the shoe and the retainer in the third embodiment. FIG. 11 is an enlarged perspective view of a contact portion between a shoe and a retainer in a fourth embodiment; FIG. 4 is a schematic diagram of a contact portion between a shoe and a retainer in another embodiment of the swash plate type hydraulic rotary machine of the present invention, (a) showing a state where the shoe is attached to the piston, and (b) showing a state where the shoe is removed from the piston; FIG. 10 is a diagram showing a state in which the

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a swash plate type hydraulic rotary machine according to the present invention will be described below with reference to the drawings.

First, a schematic configuration of a swash plate type hydraulic rotary machine common to each embodiment will be described with reference to FIGS.

FIG. 1 is a sectional view showing one embodiment of a swash plate hydraulic rotary machine of the present invention.

A swash plate type hydraulic rotary machine 1 shown in FIG. A cylinder block 5 is connected to the shaft 4 via a spline 15 so as to rotate integrally with the shaft 4 . A plurality of cylinders 6 are circumferentially formed in the circumferential direction of the cylinder block 5 (specifically, so as to be spaced apart in the circumferential direction and extend in the axial direction). is inserted and arranged so as to be able to reciprocate. A shoe 9 is pivotably connected to the end of each piston 8 protruding from the cylinder 6 (protruding end) by a spherical joint structure. side surface) is slid on the surface of a swash plate 10 that is tiltably held by the front casing 3a. In other words, the swash plate 10 is provided inside the front casing 3 a so as to face the cylinder block 5 , and one side of each shoe 9 slides on the surface (sliding surface) facing the cylinder block 5 . The retainer 11 consists of an annular flat plate positioned between each shoe 9 and each piston 8 (the protruding end thereof) and inserted through the shaft 4. A plurality of through-holes 18 are formed (see FIG. 2(a)). This retainer 11 is pressed from the cylinder block 5 via a pressing spring 14 by (the outer peripheral surface of) a retainer guide 12 into which the shaft 4 is inserted, thereby causing (one surface of) the shoe 9 to slide against the swash plate 10 (the sliding surface of the retainer 11). (moving surface) to prevent the shoe 9 from running wild during operation.

On the other hand, a valve plate 7 on which the cylinder block 5 slides is fixed to the rear casing 3b. and a low pressure port are formed.

Therefore, in the swash plate type hydraulic rotary machine 1 of the present embodiment, when the shaft 4 is rotationally driven by a prime mover (not shown), the cylinder block 5 rotates integrally with the shaft 4, and the shoes 9 slant accordingly. Each piston 8 reciprocates within the cylinder 6 by rotating while sliding on the plate 10 . When the piston 8 extends, hydraulic fluid supplied from the low-pressure port of the valve plate 7 is sucked into the cylinder 6, and when the piston 8 contracts, the hydraulic fluid sucked into the cylinder 6 is compressed by the piston 8. The compressed hydraulic fluid is discharged from the high-pressure port of the valve plate 7 to function as a hydraulic pump.

Also, in this swash plate type hydraulic rotary machine 1, hydraulic oil supplied from the high pressure port of the valve plate 7 flows into the cylinder 6, causing the piston 8 to reciprocate within the cylinder 6, causing the piston 8 to reciprocate. As each shoe 9 moves, it rotates while sliding on the swash plate 10. This rotates the cylinder block 5, and the shaft 4 rotates together with the rotation of the cylinder block 5, thereby functioning as a hydraulic motor. do.

2A and 2B are schematic views of the contact portion between the shoe 9 and the retainer 11 in the swash plate type hydraulic rotary machine 1 shown in FIG. 1. FIG. 2A is a perspective view, and FIG. and a contact portion of the retainer 11. FIG.

As described above, the retainer 11 made of an annular flat plate has a plurality of insertion holes 18 spaced apart in the circumferential direction through which the piston 8 and the shoe 9 (the spherical joint structure thereof) are inserted. 9 is held down to prevent the shoe 9 from running wild during operation. Part of the high-pressure hydraulic oil generated by the reciprocating motion of the piston 8 flows into the static pressure pocket 17 through the oil passage hole 16 provided in the shoe 9, so that the shoe 9 functions as a static pressure bearing. It operates smoothly without solid contact with the swash plate 10. - 特許庁On the other hand, the retainer 11 is pressed against the shoe 9 (the surface on the piston 8 side) by the pressing spring 14, and the sliding surface between the retainer 11 and the shoe 9 does not have a hydrostatic bearing structure. The sliding surface of the retainer 11 tends to have greater friction than the sliding surfaces of the shoe 9 and the swash plate 10 . Therefore, during operation, the shoe 9 operates in a state where it hardly rotates with respect to the retainer 11 . When the swash plate 10 is tilted with respect to the shaft 4, the piston 8, which is connected to the shoe 9 held by the retainer 11 by the spherical joint structure, slides on the shoe 9 and the spherical joint structure (rubbing movement). Therefore, it rotates inside the cylinder 6. In other words, the piston 8 has the function of a seal for suppressing leakage of hydraulic oil to the cylinder 6 and the function of a bearing by rotating on its axis.

When the swash plate hydraulic rotary machine 1 functions as a pump, the angle of the swash plate 10 should be horizontal (perpendicular to the shaft 4) in order to reduce the amount of hydraulic oil to be discharged to zero. At this time, the spherical joint structure between the piston 8 and the shoe 9 becomes unable to slide (rubbing movement), and the rotation of the piston 8 inside the cylinder 6 stops as described above. In such a state, the (outer peripheral surface of) the piston 8 always comes into contact with (the inner peripheral surface of) the cylinder 6 at the same position, and it is considered that reliability against seizure or the like is lowered.

[First embodiment]
3A to 3C are cross-sectional views of contact portions between the shoe 9 and the retainer 11 in the first embodiment.

In the first embodiment, as shown in FIGS. 3(a) to 3(c), in order to avoid reliability deterioration against the above-described seizure, for example, a shoe 9 made of an iron-based material such as steel or At least one of the contact surfaces of the retainer 11 is coated with a coating such as a DLC coating that makes the sliding surface low friction (in other words, reduces the friction (frictional force or coefficient of friction) of the sliding surface). process. In the example shown in FIG. 3(a), a low-friction coating 11c that reduces friction with the shoe 9 is applied to the contact surface (annular shape around the insertion hole 18) of the retainer 11, and the example shown in FIG. 3(b) In the example shown in FIG. The surfaces are provided with low-friction coatings 11c, 9c that reduce mutual friction.

If the friction of the contact surface of the shoe 9 or the retainer 11 becomes small, slippage tends to occur at this position. During operation, the shoes 9 are driven while sliding against the swash plate 10, but since the speeds on the inner and outer peripheral sides of the shoes 9 are different, a greater frictional force is generated on the outer peripheral side of the shoes 9. Even when the angle of the swash plate 10 is horizontal (perpendicular to the shaft 4), the shoe 9 rotates with respect to the retainer 11. As the shoe 9 rotates, the piston 8 also moves inside the cylinder 6. Rotate and improve reliability against burn-in.

As described above, in the first embodiment, at least one of the contact surfaces between the retainer 11 and the shoe 9 is coated as a process for reducing friction. It is possible to provide a rotating machine 1 .

[Second embodiment]
4A to 4C are cross-sectional views of contact portions between the shoe 9 and the retainer 11 in the second embodiment.

In the second embodiment, as shown in FIGS. 4(a) to 4(c), in order to avoid deterioration of reliability against seizure, for example, a shoe 9 made of an iron-based material such as steel or At least one of the contact surfaces of the retainer 11 is made of, for example, the aforementioned low-friction coated member, engineering plastic such as PEEK, phosphor bronze, etc., to reduce the friction (frictional force or coefficient of friction) of the sliding surface. Install the member to be used. In other words, in the second embodiment, at least one of the shoe 9 or the retainer 11 (the contact surface thereof) is configured with a separate member from the shoe 9 or the retainer 11 instead of the coating in the first embodiment. ) This is an example in which a low-friction member is installed. In the example shown in FIG. 4(a), a low-friction member 19a for reducing friction with the shoe 9 is installed on the (annular) contact surface of the retainer 11 (around the insertion hole 18), and the example shown in FIG. 4(b) 4C, a low-friction member 19b that reduces friction with the retainer 11 is installed on the (annular) contact surface of the shoe 9, and in the example shown in FIG. Low-friction members 19a and 19b are provided on the surfaces to reduce mutual friction.

The low-friction members 19a and 19b may be fixed to (the contact surfaces of) the retainer 11 or the shoe 9 by welding, press-fitting, or the like, or may be held without being fixed.

Thus, in the second embodiment, at least one of the contact surfaces between the retainer 11 and the shoe 9 is provided with the low-friction members 19a and 19b as processing for reducing friction. It is possible to provide a highly reliable swash plate hydraulic rotary machine 1 as in the embodiment. In particular, in the example in which separate low-friction members 19a and 19b are installed on the shoe 9 side and the retainer 11 side (see FIG. 4(c)), different materials can be used for the shoe 9 and the retainer 11. , is effective in lowering friction.

In the second embodiment, as described above, the low-friction members 19a and 19b composed of separate members instead of coatings are installed in order to reduce the friction, so that the material is different from that of the conventional parts. It can be selected and it becomes easier to ensure durability. Further, by installing the low-friction members 19a and 19b composed of separate members, it is possible to process the low-friction members 19a and 19b separately from the retainer 11 and the shoe 9 on which they are installed, and then install them. Therefore, the flexibility of the shape can be increased, for example, by making the sliding surface convex as described later.

[Third embodiment]
5(a) to 5(c) are cross-sectional views of contact portions between the shoe 9 and the retainer 11 in the third embodiment.

In the third embodiment, as shown in FIGS. 5(a) to 5(c), in order to more effectively avoid the deterioration of reliability due to burn-in, etc., as shown in FIGS. This is an example in which the surfaces of the low-friction members 19a and 19b (contact surfaces with the shoe 9 or the retainer 11, which are contacted members) in the second embodiment described based on this embodiment are made convex. The shoe 9 operates while being inclined with respect to the swash plate 10 due to centrifugal force and oil film on the sliding surface. By forming the surfaces of the low-friction members 19a and 19b into convex surfaces (that is, roughly bowl-shaped curved surfaces) that gradually increase in inclination with respect to the contact surface as they separate from (the central axis of) the shoe 9 (or the insertion hole 18), Hitting can be suppressed, and the reliability of the shoe 9 and the low-friction members 19a and 19b can be improved.

Thus, in the third embodiment, the surfaces of the low-friction members 19a and 19b that reduce friction have convex surfaces that increase in inclination with respect to the contact surface as they move away from the shoe 9 (going outward). It is possible to provide the swash plate type hydraulic rotary machine 1 with higher reliability than the second embodiment.

[Fourth embodiment]
FIG. 6 is an enlarged perspective view of a contact portion between shoe 9 and retainer 11 in the fourth embodiment.

In the fourth embodiment, in order to avoid deterioration of reliability against seizure and the like, friction of the sliding surface is applied to the area (annular contact surface around the insertion hole 18) in contact with the shoe 9 on the retainer 11 side. A reducing texture 20 is provided. This makes it possible to reduce the friction of the sliding surface without increasing the number of parts.

In particular, when the shoe 9 moves in the direction of the arrow X (around the rotation axis L0 together with the shaft 4, etc.) as viewed from the swash plate 10, the speed of the shoe 9 is faster on the outer peripheral side than on the inner peripheral side. It is easy to rotate in the direction of the arrow Y (around the center axis L1 of the shoe 9). In this case, a more effective effect can be obtained by using grooves with directivity such as the herringbone grooves shown in FIG. Specifically, in the texture 20 having V-shaped grooves such as herringbone grooves shown in FIG. Rotational frictional force can be reduced more than rotational frictional force in the other direction. The tip of the V-shaped groove of the texture 20 is formed in the same direction as the arrow X in the figure on the inner peripheral side of the shoe 9 in the retainer 11, and in the opposite direction to the arrow X in the figure on the outer peripheral side of the shoe 9. rotates in the opposite direction to the arrow X (rotating direction of the shaft 4), the inner peripheral side of the shoe 9 tends to rotate in the same direction as the arrow X in the figure, and the shoe 9 (the central axis L1 of the shoe 9 around) becomes easier to rotate in the direction of arrow Y in the figure.

In the example shown in FIG. 6, the texture 20 is formed on the (annular) contact surface of the retainer 11 (around the insertion hole 18), but the texture may be formed on the (annular) contact surface of the shoe 9. However, of course, both the retainer 11 and the (annular) contact surface of the shoe 9 may be textured.

As described above, in the fourth embodiment, at least one of the contact surfaces between the retainer 11 and the shoe 9 is provided with the texture 20 as processing for reducing friction, more specifically, the inclination of the swash plate 10 is horizontal (shaft 4) and has a directionality corresponding to the direction of rotation when it is operated (rotated). It is possible to provide a swash plate type hydraulic rotary machine 1 with even higher reliability than the first to third embodiments.

As described above, in the swash plate type hydraulic rotary machine 1 of the present embodiment, by introducing each structure described with reference to FIGS. It becomes possible to provide the plate-type hydraulic rotary machine 1 .

In each of the above-described embodiments, the spherical joint structure is provided on the shoe 9 side. Piston 8 and shoe 9 may be connected. Note that FIG. 7B shows an example in which a low-friction member 19a is provided on the retainer 11 side (see also FIG. 4A).

In addition, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

1 swash plate type hydraulic rotary machine 2 casing 3a front casing 3b rear casing 4 shaft (rotating shaft)
5 Cylinder Block 6 Cylinder 7 Valve Plate 8 Piston 9 Shoe 9c Low Friction Coating (First Embodiment)
10 swash plate 11 retainer 11c low friction coating (first embodiment)
12 Retainer guide 13 Bearing 14 Pressure spring 15 Spline 16 Oil passage hole 17 Static pressure pocket 18 Insertion hole 19a, 19b Low friction member (second and third embodiments)
20 Texture (Fourth Embodiment)

Claims (3)

A casing, a rotating shaft provided rotatably in the casing, and a plurality of cylinders provided in the casing so as to rotate integrally with the rotating shaft and spaced apart in the circumferential direction and extending in the axial direction are formed. a cylinder block, a plurality of pistons that are reciprocally inserted into the cylinders of the cylinder block and project from the cylinders at one end in the axial direction; shoes attached to projecting ends of the pistons; A swash plate provided in the casing facing the cylinder block and having a sliding surface on which the shoes slide on the surface facing the cylinder block; and the projecting ends of the shoes and the pistons. a retainer positioned between the shoes to contact the sliding surface of the swash plate; and a retainer positioned between the retainer and the cylinder block to press the retainer against the swash plate by an outer peripheral surface thereof. A swash plate hydraulic rotary machine comprising a retainer guide,
At least one of the contact surfaces of the retainer and the shoe is provided with a friction-reducing member as friction-reducing processing ,
A swash plate type hydraulic rotary machine, wherein the surface of the member has a convex surface that slopes with respect to the contact surface as the distance from the shoe increases . A casing, a rotating shaft provided rotatably in the casing, and a plurality of cylinders provided in the casing so as to rotate integrally with the rotating shaft and spaced apart in the circumferential direction and extending in the axial direction are formed. a cylinder block, a plurality of pistons that are reciprocally inserted into the cylinders of the cylinder block and project from the cylinders at one end in the axial direction; shoes attached to projecting ends of the pistons; A swash plate provided in the casing facing the cylinder block and having a sliding surface on which the shoes slide on the surface facing the cylinder block; and the projecting ends of the shoes and the pistons. a retainer positioned between the shoes to contact the sliding surface of the swash plate; and a retainer positioned between the retainer and the cylinder block to press the retainer against the swash plate by an outer peripheral surface thereof. A swash plate hydraulic rotary machine comprising a retainer guide,
At least one of the contact surfaces of the retainer and the shoe is textured to reduce friction as processing to reduce friction ,
A swash plate type hydraulic rotary machine , wherein the texture reduces rotational friction in one direction around the shoe more than rotational friction in the other direction . In the swash plate type hydraulic rotary machine according to claim 2 ,
The texture is such that when the swash plate rotates perpendicular to the rotating shaft, the outer peripheral side of the shoe rotates in a direction opposite to the rotating direction of the rotating shaft, and the inner peripheral side of the shoe rotates about the rotating shaft. A swash plate type hydraulic rotary machine characterized by reducing rotational friction around said shoe so that it rotates in the same direction as the direction of rotation.

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