CN108457851B

CN108457851B - Retainer and hydraulic pump or motor including the same

Info

Publication number: CN108457851B
Application number: CN201711029750.1A
Authority: CN
Inventors: 王晓刚; 郭志敏; 卡斯滕·费宾
Original assignee: Danfoss Power Solutions Zhejiang Co Ltd
Current assignee: Danfoss Power Solutions Zhejiang Co Ltd
Priority date: 2017-02-22
Filing date: 2017-10-27
Publication date: 2020-10-02
Anticipated expiration: 2037-10-27
Also published as: CN108457851A

Abstract

A cage for a hydraulic pump or motor, the cage having a working surface comprising: a force receiving surface for receiving a force applied by a component of the hydraulic pump or motor at the time of the play; and an end surface recessed relative to the force-bearing surface.

Description

Retainer and hydraulic pump or motor including the same

Technical Field

Embodiments of the present invention generally relate to cages, and more particularly, to a cage, and a hydraulic pump or motor including the same.

Background

Under the condition of high rotating speed or high working pressure of the hydraulic pump or the motor, the return disc and the sliding shoes can axially shift. In order to limit the maximum axial play of the return disc and the shoes, a retainer or a pressure plate is generally used, which, when mounted in place, is not in contact with the return disc and the shoes, but rather is kept at a distance, so that in operation, the play of the return disc and the shoes is limited to a certain extent. In general, the surface of the portion of the cage that limits the play of the return disc and the shoes (i.e., the portion that bears the stress) is referred to as the working surface, which bears the force generated when in contact with the moving return disc and shoes.

However, with the conventionally designed cage, at a higher rotation speed or a higher working pressure, stress is excessively concentrated at both end portions of the portion that bears the stress, so that the physical bearing limit of the material constituting the cage is easily exceeded, resulting in partial cracking of the portion that bears the stress, severely reducing the service life of the cage, the hydraulic pump, or the motor, and technicians have to frequently replace the cage, which increases the maintenance cost of the equipment.

Disclosure of Invention

It is an object of the present invention to overcome or solve at least one of the above problems and disadvantages of the prior art.

In one aspect, there is provided a cage for a hydraulic pump or motor, the cage having a working surface comprising:

a force receiving surface for receiving a force applied by a component of the hydraulic pump or motor at the time of the play; and an end surface recessed relative to the force-bearing surface.

In one embodiment, the working surface comprises two of the end surfaces on opposite sides of the force receiving surface.

In one embodiment, the end surface includes one or a combination of a slope inclined with respect to the force receiving surface, a parallel surface parallel to the force receiving surface, and a curved surface.

In one embodiment at least one long side of the working surface has an arc shape and the end surface has an arc angle in the range of 4-8 °.

In one embodiment, there is a height difference (Δ H) between the force-bearing surface and the lowest point of the end surface, said height difference (Δ H) being in the range of 0.05mm to 0.5 mm.

In one embodiment, the cage has a first portion having a first surface that is raised relative to the working surface and a second portion on which the working surface is located.

In one embodiment, the first portion has an arcuate surface that joins with the first surface and a working surface of the second portion, the arcuate surface having a center of curvature that is the same as the arcuate shape of the working surface.

In another aspect, a hydraulic pump or motor is provided, comprising the cage of the above embodiments.

Drawings

Other features and advantages of the invention will be better understood with reference to the examples and the accompanying drawings, in which:

figure 1 is a perspective schematic view of a cage according to an embodiment of the invention;

FIG. 2 is an enlarged side schematic view of the end indicated by the dashed box in FIG. 1 according to an embodiment of the invention;

FIG. 3 is a schematic top view of the cage of FIG. 1 according to an embodiment of the invention;

FIG. 4 is a graph showing the variation of the stresses carried by the ends of the cage and the deformations that occur as the arc angle varies, according to an embodiment of the invention; FIG. 5 is a side schematic view of a holder in place in a hydraulic pump or motor according to one embodiment of the invention.

Detailed Description

In the following description, like reference numerals will be used to describe like features through different embodiments of the present invention.

Unless otherwise stated, the technical features specifically described for a given embodiment may be combined with the technical features described by way of non-limiting example in the case of other embodiments.

FIG. 1 illustrates a cage or platen 200 according to one embodiment of the present invention. Which is used to limit the play of, for example, a return disc 230 or a shoe 240 of a hydraulic pump or motor, and fig. 5 is a side view schematically illustrating the cage 200 according to an embodiment of the present invention when it is installed in place in the hydraulic pump or motor. For clarity of illustration, the three parts of the cage 200, the return disc 230 and the slipper 240 are only schematically shown in fig. 5 when mounted in place, the other parts being omitted, the screw 250 securing the cage 200 in place, and there being a gap between the cage 200 and the return disc 230, which gap is small, typically 0.01mm-0.1mm, but is shown in exaggerated form for clarity, as will be described below.

As shown in fig. 1, the holder 200 has a first portion 210 and a second portion 220, and the height of the first portion 210 may be higher than, equal to, and lower than the height of the second portion 220 according to practical applications, and all three cases are applicable to the present invention, and for convenience of description, only the case where the second portion 220 is recessed downward with respect to the first portion 210 to form a stepped structure will be described, and it should be understood that the other two cases are also possible. The first portion 210 has a first surface 212 on which

screw holes

216, 218 are provided to enable screw coupling by screws 250 in one example, for example, the

screw holes

216, 218 are located at both ends of the first surface 212 in a length direction, and the retainer 200 is fixed in the hydraulic pump or motor by screw coupling to limit play of a return disc 230 or a slipper 240 of the hydraulic pump or motor. It will be appreciated that the cage 200 shown in the figures is one-piece, i.e. the first part 210 is integrally formed with the second part 220, but the cage may also be split, i.e. the first part 210 and the second part 220 are separate from each other, or the cage may be made up of two halves in the circumferential direction (each half comprising parts like the first part 210 and the second part 220), or more. These cage variants fall within the scope of protection of the present invention.

As shown in fig. 1, the second portion 220 has a working surface comprising: a force receiving surface 222 for receiving a force applied by a component of the hydraulic pump or motor during play, the first surface 212 being raised relative to the working surface; and

end surfaces

224, 226 that are recessed in a downward direction in fig. 1 with respect to the force-receiving surface 222, such that the

end surfaces

224, 226 do not contact the return disc 230 or the slipper 240 in operation, there being a height difference ah (see fig. 2) between the force-receiving surface 222 and the lowest point of the end surfaces. The

end surfaces

224, 226 are located on opposite end sides or edge sides of the force-bearing surface 222, as shown in fig. 1. As will be understood below, although the working surface is illustrated in fig. 1 as having two

recessed end surfaces

224, 226 on opposite end sides or edge sides of the force receiving surface, the working surface may be provided with only one

recessed end surface

224 or 226 on one end side or edge side of the force receiving surface 222, as desired.

According to an embodiment of the present invention, when the cage 200 is in place and in operation, only the force bearing surface 222 is in contact with and carries a force such as a moving return disc 230 or slipper 240 of a hydraulic pump or motor, the

recessed end surfaces

224, 226 do not contact the return disc 230 or slipper 240, thereby reducing or eliminating stress concentrations at the ends or peripheral edges of the cage.

In one embodiment, the first portion 210 may further include an arcuate surface 214, the arcuate surface 214 being joined with the first surface 212, the force bearing surface 222, and the

end surfaces

224, 226. In one example, the arcuate surface 214 is perpendicular to at least one of the first surface 212, the force bearing surface 222, and the

end surfaces

224, 226. When the cage 200 is in place, the force bearing surface 222 of the second portion 220 does not contact the return plate 230 or the skid shoe 240 (not shown), but rather remains a distance, as described above. In operation, the return disc 230 or the slipper 240 generates play in the axial direction (i.e., in the up-down direction in fig. 5), and the force receiving surface 222 receives the force generated when contacting the moving return disc 230 or the slipper 240, thereby achieving the effect of limiting the play of the return disc 230 or the slipper 240.

In one embodiment, as shown in FIG. 1, the second portion 220 and/or the first portion 210 are generally arcuate, the working surface may also be arcuate or at least one long side of the working surface may be arcuate. In one example, the working surface has the same radius of curvature, center of curvature, and arc angle in the direction of the arc as the curved surface 214. It will be appreciated that the shape of the first portion, second portion or other force receiving surface forming the stepped configuration is not limited thereto, so long as it matches the shape of the return disc 230 or slipper 240 it defines. In one example, the cage 200 is made of a copper alloy material and the

end surfaces

224, 226 are formed, for example, by milling or forging a blank. The number of downwardly recessed ends may be 1 or 2 as desired, with fig. 1 showing an exemplary embodiment having 2 downwardly recessed ends.

FIG. 2 illustrates an enlarged side schematic view of the end indicated by the dashed box in FIG. 1, according to one embodiment of the invention. As shown, a height difference Δ H is formed between the force-receiving surface 222 and the lowest point of the

end surfaces

224, 226, the height difference Δ H preferably being in the range of 0.05mm to 0.5 mm. In the illustrated embodiment, the

end surfaces

224, 226 include parallel faces (as indicated by solid line S) that are parallel to the force receiving surface 222₁Indicated by dashed line S), an inclined plane (indicated by dashed line S) relative to the force-receiving surface 222₃Shown) or curved (by dotted line S)₂Shown) and parallel surface S₁Inclined plane S₃And a curved surface S₂In any combination, it should be understood that the

end surfaces

224, 226 are not limited to include the 3 forms described, as the actual situation requires, and the

actual end surfaces

224, 226 need not necessarily include the parallel surface S parallel to the force receiving surface₁It may consist of only the bevel S₃Or curved surface S₂Composed of, or having any shape as long as the

end surfaces

224, 226 are lower than the force-receiving surface 222.

In fig. 2, the intermediate portion and the 2 downwardly recessed end portions preferably constitute a stepped structure, but the intermediate portion and the downwardly recessed end portions may also be formed in other structures, for example, a ramp structure when a ramp is employed.

Fig. 3 shows a schematic top view of the cage of fig. 1, and fig. 4 is a graph showing the variation of the stresses carried by the ends of the cage 200 and the deformation that occurs as the arc angle varies, according to one embodiment of the invention. The arc angles α, β (as shown in fig. 4) of the ends of the cage 200, and more particularly the

end surfaces

224, 226, are preferably in the range of 4 ° to 8 °, or their lengths (or arc lengths) are preferably in the range of 3mm to 10mm, avoiding the area of the

end surfaces

224, 226 being so small as to be detrimental to reducing or eliminating stress concentrations at the ends, while allowing the area of the force-bearing surface 222 to be large enough to be able to carry the force of the return disc 230 or the slipper 240. The width of the

end surfaces

224, 226 is preferably the same as the width of the force receiving surface 222.

It has been found experimentally that the length or arc angle of the end portion has a greater effect on stress reduction and stress-induced deformation relative to the height difference Δ H, the shape of the

end surfaces

224, 226 and the width of the end surfaces 224, 226: as shown in fig. 4, the stress and deformation at the end portions are drastically reduced when the arc angle is in the range of 0 ° to 4 °, which indicates that the cage of the present invention is provided with the recessed end portions capable of significantly reducing or eliminating the concentration of stress at the end portions and significantly reducing or eliminating the deformation of the end portions, as compared with the conventional cage without the recessed end portions; when the arc angle exceeds 4 °, the stress and deformation at the end portion are less reduced, and the curve tends to be gentle, which means that when the arc angle exceeds 4 °, the influence of the end portion on the reduction of the stress and deformation is gradually weakened, and in general, the larger the arc angle or length of the end portion, the more the stress and deformation are reduced.

More specifically, referring to table 1, the ratio of the stress and the deformation carried by the lower end at a certain arc angle to the stress and the deformation carried by the end at an arc angle of 0 ° is referred to as the stress ratio and the deformation ratio, respectively, and these 2 parameters describe well the variation of the stress and the deformation at the end with the arc angle. Wherein, when the arc angle is 8 degrees, the stress ratio and the deformation ratio are respectively and rapidly reduced to 52.69 percent and 47.57 percent when the arc angle is 0 degrees; as the arc angle increased to 10 °, the stress ratio and the deformation ratio slowly dropped to 51.26% and 46.82%, respectively, at an arc angle of 0 °. This is the same physical meaning as represented in fig. 4, but the greater the arc angle or length of the ends is not the better, as this would reduce the area of the force-receiving surface 222, such that the force-receiving surface 222 is not able to carry the force of the return disc 230 or the slipper 240, as described above. Therefore, a good balance needs to be found between the arc angle of the end portion and the area of the force receiving surface 222 so that the end portion can both reduce more stress and deformation and the force receiving surface 222 can also carry larger forces. It was found that it is preferable to keep the arc angles α, β in the range of 4 ° to 8 °, respectively.

TABLE 1

Although fig. 1-3 show 2 substantially identical downwardly

concave end surfaces

224, 226, it should be understood that the various parameters defining the

end surfaces

224, 226 need not be the same, i.e., the height difference ah, length, arc angles α, β between the

end surfaces

224, 226 and the force-bearing surface 222 can be different as desired.

The

end surfaces

224, 226 are capable of significantly reducing the maximum stress at the ends of the second portion 220 as may be found by quality qualification tests such as high pressure endurance tests, high and low pressure cycling endurance tests. Compared with the conventional retainer, the retainer 200 according to the embodiment of the invention can reduce the maximum stress by more than 45%, is beneficial to the hydraulic pump or the motor to work at higher rotating speed or working pressure, can not crack when bearing higher stress, can be applied to a more severe working environment, expands the application range of the hydraulic pump or the motor, and has higher reliability and durability, thereby prolonging the service life of the hydraulic pump or the motor and reducing the maintenance cost.

While at least one exemplary embodiment has been presented in the foregoing description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing description will provide those skilled in the art with a convenient road map for implementing the exemplary operation. It should be understood that various changes may be made to the exemplary embodiments without departing from the scope of the invention as set forth in the following claims.

Claims

1. A cage (200) for a hydraulic pump or motor, characterized by: the cage has a first portion (210) and a second portion (220), the second portion having a working surface thereon, the working surface being arcuate, the first portion having a first surface (212) convex relative to the working surface, and an arcuate surface (214) joining the first surface (212) and the working surface, the arcuate surface (214) having a center of curvature that is the same as the arcuate shape of the working surface, wherein,

the work surface includes:

a force-bearing surface (222), the force-bearing surface (222) for bearing a force exerted by a component of a hydraulic pump or motor upon play; and

an end surface (224, 226), the end surface (224, 226) being recessed relative to the force-bearing surface (222), the end surface (224, 226) having an arc angle (a, β) in a range greater than 0 ° and equal to or less than 8 °.

2. The cage (200) of claim 1, wherein: the working surface comprises two of said end surfaces (224, 226) located on opposite sides of the force-bearing surface (222).

3. Cage (200) according to claim 1 or 2, characterized in that: the end surface comprises a slope (S) inclined with respect to the force-bearing surface (222)₃) A parallel plane (S) parallel to the force-receiving surface (222)₁) And curved surface (S)₂) One or a combination thereof.

4. Cage (200) according to claim 1 or 2, characterized in that: there is a height difference (Δ H) between the force-bearing surface (222) and the lowest point of the end surfaces (224, 226), said height difference (Δ H) being in the range of 0.05mm to 0.5 mm.

5. A hydraulic pump or motor characterized by: the hydraulic pump or motor comprising a cage (200) according to any of claims 1-4.