JP3754181B2 - Hydraulic pump - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a hydraulic pump that is suitable for use in a power source such as a power steering device of an automobile.
[0002]
[Prior art]
As a hydraulic pump of this type, for example, in Japanese Patent Application Laid-Open No. 7-279871, a pump unit is accommodated between a pump body and a pump cover, and a bearing bush is inserted into a bearing hole formed through the pump body. A hydraulic pump having a structure in which a drive shaft for driving a pump unit is supported by the bearing bush and a seal chamber is formed at the end of the bearing hole is disclosed.
[0003]
Further, on the inner peripheral side of the cylindrical bearing bush inserted into the bearing hole of the pump body, a single oil groove is formed in a spiral shape that opens to both ends of the bearing bush. The hydraulic oil leaking on the pump unit side is guided to the seal chamber through the groove.
[0004]
In such a conventional example, the pump unit is driven by the drive shaft supported by the bearing bush. That is, a pulley or the like is attached to the end of the drive shaft protruding from the pump body, and is driven to rotate by a belt or the like wound around the pulley. Thereby, the function of the hydraulic pump is exhibited.
[0005]
At this time, oil is leaked from the pump unit as the pump unit is driven, and the oil leak is guided from the bearing hole into the oil groove of the bearing bush. The hydraulic oil flowing through the oil groove of the bearing bush is guided to the seal chamber while lubricating between the bearing bush and the drive shaft. For lubrication between the bearing bush and the drive shaft, an appropriate bearing gap is provided between the bearing bush and the drive shaft. Lubricating oil is supplied to the bearing gap from the oil groove, and as the drive shaft rotates. Lubricating is accomplished by creating an oil film, supporting the drive shaft with the oil film, and avoiding direct metal contact between the drive shaft and the bearing bush.
[0006]
[Problems to be solved by the invention]
By the way, when the pump unit is driven by the drive shaft, the drive shaft is supported by a bearing bush, and an appropriate bearing gap is formed between the bearing bush and the drive shaft. It is possible to incline within the cylindrical bearing bush. For this reason, the both end sides of the bearing bush come into strong contact with the drive shaft, while the contact surface pressure with the drive shaft at the substantially central portion in the axial direction of the bearing bush is not so large.
[0007]
Therefore, in the lubrication between the bearing bush and the drive shaft, it is important that a stable oil film is formed at both ends of the bearing bush rather than the substantially central portion in the axial direction of the bearing bush. It is desirable to maintain a lubricated state.
[0008]
However, in the above-described conventional example, an oil groove is formed on the inner peripheral side of the bearing bush over the entire axial length of the bearing bush, and the working oil lubricates the inner surface of the bearing bush to the seal chamber. As a result, the formation of an oil film is hindered by the oil groove, and there is a risk of poor lubrication particularly at both axial ends of the bearing bush. That is, the formation of the lubricating oil film is accomplished by generating oil film pressure by the wedge action of oil when the drive shaft rotates and oil is drawn into a wedge-shaped clearance gap narrowed in the rotation direction. However, the presence of the oil groove makes it impossible to obtain a sufficient rust effect, and it is difficult to form a stable oil film, which may cause poor lubrication.
[0009]
The present invention has been devised in view of such a conventional situation, and provides a hydraulic pump that does not cause poor lubrication by forming a stable lubricating oil film between a drive shaft and a bearing bush. Objective.
[0010]
[Means for Solving the Problems]
Accordingly, the invention according to claim 1 is configured such that a pump unit is accommodated between a pump body having a bearing hole penetratingly formed therein and a pump cover, and a drive shaft for driving the pump unit and the drive thereof are disposed in the bearing hole. In a hydraulic pump in which a bearing bush for bearing a shaft is inserted and a seal chamber is formed at the end of the bearing hole, the seal chamber is opened from the pump unit side and is opened between the bearing hole and the bearing bush. An oil groove that communicates with the hydraulic oil for lubrication is formed on the inner peripheral side of the bearing bush, and is located in a substantially central portion in the axial direction of the bearing bush. to form a, the bottom of the groove, characterized in that the formation of the oil hole in communication with the oil groove.
[0011]
According to a second aspect of the present invention, in the configuration of the first aspect of the present invention, the groove formed in the bearing bush is within a dimension range of approximately 1/3 or less of the axial length of the bearing bush. According to a third aspect of the present invention, in the configuration of the first aspect of the present invention, the axially opposite ends of the concave groove are oil grooves on the inner peripheral side of the bearing bush. It is characterized in that a bearing surface not formed is formed .
[0012]
Here, the hydraulic pump includes various liquid pumps including but not limited to a vane pump, a plunger pump, a piston pump, and the like.
[0013]
The said structure WHEREIN: The said hydraulic pump exhibits the function as a pump, when a drive shaft is rotated and a pump unit is driven.
[0014]
The oil leakage from the pump unit that occurs when the pump unit is driven is once guided into the bearing hole, and after lubricating the inside of the bearing hole, the oil leaks into the seal chamber via an oil groove formed in the bearing hole. Led.
[0015]
That is, the oil leakage from the pump unit guided into the bearing hole is supplied directly from the bearing hole on the pump unit side to the inner surface of the bearing bush and also supplied from the seal chamber side to the inner surface of the bearing bush. Is done. Further, a part of the oil leakage guided through the oil groove is supplied to the concave groove from the oil hole communicating with the oil groove, and is supplied from the concave groove to the inner surface of the bearing bush.
[0016]
The oil supplied to the inner surface of the bearing bush is drawn in a wedge shape in the bearing gap narrowed in the rotation direction by the rotation of the drive shaft, and the oil film pressure is generated by the wedge action of the oil. A good lubricating oil film is formed.
[0017]
Here, when the pump unit is driven by the drive shaft, the drive shaft is supported by a bearing bush, and an appropriate bearing gap is formed between the bearing bush and the drive shaft. Can be inclined in the cylindrical bearing bush, and in particular, the both ends of the bearing bush come into strong contact with the drive shaft. In the present invention, a stable lubricating oil film is formed on both ends of the bearing bush. Is formed, and poor lubrication is advantageously prevented.
[0018]
That is, the inner circumferential surface of the bearing bush is formed with a circumferential concave groove located at a substantially central portion in the axial direction of the bearing bush, but the remaining portion, that is, the bearing with which the drive shaft comes into strong contact. On both ends of the bush, there are no oil grooves or the like that obstruct the formation of the lubricating oil film. In addition, oil for lubrication is sufficiently supplied to the inner peripheral surface of the bearing bush not only from both ends of the bearing bush but also from the concave groove in the central portion. For this reason, in particular, a stable lubricating oil film is formed on both end sides of the bearing bush with which the drive shaft comes into strong contact, and poor lubrication is advantageously prevented.
[0019]
Therefore, a stable lubricating oil film is formed between the drive shaft and the bearing bush, and a hydraulic pump that does not cause poor lubrication can be obtained.
[0020]
According to a second aspect of the present invention, since the concave groove is formed within a size range of approximately 1/3 or less of the axial length of the bearing bush, the bearings at both axial ends of the bearing bush are provided. A sufficient area is secured.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on the drawings as an aspect applied to a hydraulic pump of a power steering device.
[0022]
1 is a sectional view of a hydraulic pump showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, FIG. 3 is a drawing showing a developed state of a bearing bush, and FIG. 4 is a bearing in a bearing hole. It is sectional drawing of the bump body of the state which inserted the bush.
[0023]
In the figure, 1 is a pump body made of a metal material such as an aluminum alloy, 2 is a pump cover made of the same metal material, and a pump unit 3 is housed between the pump body 1 and the pump cover 2. Specifically, an annular recess 4 is formed between the pump body 1 and the pump cover 2, and the pump unit 3 is housed in the annular recess 4.
[0024]
The pump unit 3 is a vane pump unit in this embodiment, and a rotor 6 in which a plurality of vanes 5 are mounted so as to be freely projecting and retracting in a radial direction is accommodated in a cam ring 7. , 9 is provided. A pump chamber 10 is formed between the cam ring 7, the rotor 6 and the adjacent vanes 5. The volume of the pump chamber 10 is changed by the rotation of the rotor 6, and a suction section is formed in a portion where the volume increases due to the change, and a discharge section is formed in a portion where the volume is reduced. The side plates 8 and 9 facing the discharge section are formed with notch passages 8a and 9a that release radially outwardly, and discharge oil (high pressure chamber) of the annular recess 4 on the outer periphery of the cam ring 7 is supplied to the pump discharge oil. 11 to be discharged. Further, a suction port (not shown) is formed through the side plate 9 facing the suction section.
[0025]
A bearing hole 12 is formed through the pump body 1, and a seal chamber 13 is formed at the end of the bearing hole 12. An oil groove 14 communicating from the pump unit 3 side to the seal chamber 13 is formed in the bearing hole 12 (see FIG. 2 and FIG. 4). The oil groove 14 has an arc-shaped cross section and is formed substantially linearly in the axial direction of the bearing hole 12, and leaks oil from the pump unit 3, specifically between the rotor 6 and the side plates 8, 9. The hydraulic fluid that leaks from the pump and the slight hydraulic fluid that leaks from the joint between the pump body 1 and the side plate 9 are guided from the bearing chamber 12 of the pump unit 3 into the seal chamber 13.
[0026]
The pump body 1 has a suction passage 15 that communicates the pump chamber 10 in the suction section with an oil storage tank (not shown), and a discharge passage that communicates the pump chamber 10 in the discharge section and the actuator of the power steering device (not shown). 16 and a spool valve receiving hole 17 sealed at one end are formed.
[0027]
The suction passage 15 branches in two directions at the joint with the side plate 9, and an arc-shaped suction port 18 is formed at the tip. The suction port 18 is formed facing a suction port (not shown) formed in the side plate 9. The suction passage 15 communicates with the seal chamber 13 through a low pressure passage 19 substantially parallel to the bearing hole 12 (see FIG. 2).
[0028]
The discharge passage 15 is bent radially outward at the joint with the side plate 9, and an orifice passage 21 communicating with a discharge port 20 formed in the side plate 9 is formed.
[0029]
A bearing bush 22 is inserted into the bearing hole 12. The bearing bush 22 is formed by rounding a flat plate member into a cylindrical shape. The bearing bush 22 is located on the inner peripheral side of the bearing bush 22 at a substantially central portion in the axial direction of the bearing bush 22 and has a circumferential recess. A groove 23 is formed. The groove 23 is preferably formed within a dimension range of approximately 1/3 or less of the axial length L of the bearing bush 22 in order to secure a bearing area. In this embodiment, the width of the groove 23 is The dimension l is approximately 1/5 of the axial length L of the bearing bush. An oil hole 24 communicating with the oil groove 14 formed in the bearing hole 12 is formed at the bottom of the concave groove 23 (see FIG. 3). Therefore, the bearing bush 22 is inserted into the bearing hole 12 so that the oil hole 24 faces the oil groove 14.
[0030]
Reference numeral 25 denotes a drive shaft for driving the pump unit 3, and the drive shaft 25 is inserted into the bearing hole 12 while being supported by the bearing bush 22. The drive shaft 25 is formed with a serration 26 at the tip side thereof, and the serration 26 passes through the through hole 9b of the side plate 9 and is fitted into the serration hole 27 of the rotor 6, thereby the drive shaft. 25 can rotate the rotor 6, that is, can drive the pump unit 3. The tapered tip of the drive shaft 25 is loosely fitted in the through hole 8 b of the side plate 8.
[0031]
A spool valve 30 for controlling the flow rate is slidably fitted in the spool valve housing hole 17. The spool valve 30 defines the inside of the spool valve accommodation hole 17 as a first pressure chamber 17a and a second pressure chamber 17b, and always uses a spring force of a control spring 31 housed in the second pressure chamber 17b. The drain passage 33 that is biased toward the pressure chamber 17a and is in a normal state and communicates with the suction passage 15 at the land portion 32 is closed. The open end of the first pressure chamber 17a defined by the spool valve 30 faces the discharge chamber 11 and forms an introduction passage 34 that guides pump discharge oil.
[0032]
The pump body 1 is formed with a passage 35 that communicates with the discharge passage 16 and communicates with a discharge port (not shown) to guide hydraulic oil to a power steering device (not shown), that is, an actuator. Further, the passage 35 and the second pressure chamber 17b communicate with each other via a passage 36 so that the pressure in the discharge passage 16 is guided into the second pressure chamber 17b.
[0033]
Reference numeral 39 denotes a pressure switch attached to the pump cover 2. The pressure switch 39 has a fixed contact 39 a and a movable contact 39 b, and the movable contact 39 b faces the passage 40 communicating with the discharge chamber 11 at the tip, so that the pressure in the discharge chamber 11 is increased. It is possible to respond to. Further, the inside of the recess 41 to which the pressure switch 39 is screwed is communicated with the through hole 9b of the side plate 9 through a radial passage 42 and an axial passage 43.
[0034]
The pump body 1 and the pump cover 2 are connected and fixed to each other by bolts or the like not shown, and the joint between the pump body 1 and the pump cover 2 is sealed by a seal ring 44 and discharged. The hydraulic oil discharged into the chamber 11 is prevented from leaking to the outside.
[0035]
A seal ring 45 is provided between the pump cover 2 and the side plate 8, and the seal ring 45 partitions the discharge chamber 11 and the through hole 8 b of the side plate 8. Reference numeral 46 denotes a seal member that is provided in the seal chamber 13 and seals the drive shaft 25.
[0036]
A drive means such as a pulley that is rotationally driven by an internal combustion engine (not shown) is attached to the projecting end of the drive shaft 25 from the pump body 1.
[0037]
According to such a configuration, the drive shaft 25 is rotationally driven via a pulley or the like (not shown), and the rotor 6 connected to the drive shaft 25 is rotationally driven. When the rotor 6 is driven to rotate, the hydraulic oil is sucked into the pump chamber 10 in the suction section whose volume is expanded by the rotation of the rotor 6 from the suction passage 15 through the suction port 18 and is subjected to a pump action. Thereafter, the ink is discharged into the discharge chamber 11 from the pump chamber 10 in the discharge section where the volume is reduced. Thereafter, the hydraulic oil discharged into the discharge chamber 11 is guided into the first pressure chamber 17a through the introduction passage 34. The hydraulic fluid guided into the first pressure chamber 17a is guided to the actuator of the power steering apparatus (not shown) through the orifice passage 21, the discharge passage 16, and the passage 35.
[0038]
At this time, in the normal state shown in FIG. 1, the spool valve 30 is urged toward the first pressure chamber 17a by the control spring 31, and the drain passage 33 is closed by the land portion 32 of the trunk portion. The entire amount of pump discharge oil introduced into the first pressure chamber 17a is guided to an actuator (not shown) through the orifice passage 21. On the other hand, when the pump rotational speed increases, the pump discharge oil amount increases, and the pump discharge oil amount introduced into the first pressure chamber 17a increases, the first pressure chamber is under restricted flow by the orifice passage 21. While the hydraulic oil in 17a is guided to the discharge passage 16, the spool valve 30 moves to the right based on the differential pressure across the orifice passage 21 and compresses the control spring 31 until it reaches a predetermined length. The drain passage 33 is opened, and excess oil is recirculated from the drain passage 33 to the suction passage 15 and an oil storage tank (not shown).
[0039]
As a result, the hydraulic fluid guided to the power steering device (not shown) via the discharge passage 16 and the passage 35 is controlled to a predetermined flow rate.
[0040]
In addition, as the pump unit 3 is driven, the hydraulic oil is discharged into the discharge chamber 11, while a gap formed for lubrication is formed between the rotor 6 and the side plates 8 and 9. Will leak. In addition, a part of the hydraulic fluid leaks from the joint between the pump body 1 and the side plate 9.
[0041]
The oil leakage from the pump unit 3 is once collected in the bearing hole 12 on the pump unit 3 side. That is, oil leakage between the rotor 6 and the side plate 8 is introduced into the through hole 8b of the side plate 8 and then passed through the meshing gaps of the serrations 26 and 27 and the through hole 9b of the side plate 9. Are assembled in the bearing hole 12. Further, oil leakage between the rotor 6 and the side plate 9 is collected in the bearing hole 12 through the through hole 9b of the side plate 9.
[0042]
The oil collected in the bearing hole 12 on the side plate 9 side is lubricated in the bearing hole 12 and then guided into the seal chamber 13 through an oil groove 14 formed in the bearing hole 12. The hydraulic oil guided into the seal chamber 13 lubricates the seal member 46 in the seal chamber 13 and then returns to the suction passage 15 and the oil storage tank (not shown) through the low-pressure passage 19. Become.
[0043]
At this time, the oil leakage from the pump unit 3 guided into the bearing hole 12 is supplied directly to the inner surface of the bearing bush 22 from the bearing hole 12 on the pump unit 3 side, and also on the seal chamber 13 side. To the inner surface of the bearing bush 22. Further, part of the oil leakage guided through the oil groove 14 is supplied into the concave groove 23 from the oil hole 24 communicating with the oil groove 14, and is supplied from the concave groove 23 to the inner surface of the bearing bush 22.
[0044]
The oil supplied to the inner surface of the bearing bush 22 is drawn in a wedge shape into the bearing gap narrowed in the rotation direction when the drive shaft 25 rotates, and an oil film pressure is generated by the wedge action of the oil. As a result, a good lubricating oil film is formed.
[0045]
Here, when the pump unit 3 is driven by the drive shaft 25, the drive shaft 25 is supported by the bearing bush 22, and an appropriate bearing gap is formed between the bearing bush 22 and the drive shaft 25. Therefore, the drive shaft 25 can be inclined in the cylindrical bearing bush 22, and in particular, both ends of the bearing bush 22 come into strong contact with the drive shaft 25. A stable lubricating oil film is formed at both ends of the bush 22, and poor lubrication is advantageously prevented.
[0046]
That is, the inner circumferential surface of the bearing bush 22 is formed with a circumferential concave groove 23 located at a substantially central portion in the axial direction of the bearing bush 22, but the remaining portion, that is, the drive shaft 25 is formed. No oil grooves or the like that inhibit the formation of the lubricating oil film are formed on both end sides of the bearing bush 22 that is in strong contact. Further, the lubricating oil is sufficiently supplied to the inner peripheral surface of the bearing bush 22 not only from both ends of the bearing bush 22 but also from the concave groove 23 in the central portion. For this reason, in particular, a stable lubricating oil film is formed on both end sides of the bearing bush 22 with which the drive shaft 25 is in strong contact, and poor lubrication is prevented.
[0047]
Therefore, a stable lubricating oil film is formed between the drive shaft 25 and the bearing bush 22 to obtain a hydraulic pump that does not cause poor lubrication.
[0048]
Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment and can be changed without departing from the gist of the invention. For example, the oil groove 14 formed in the bearing hole 12 may not only be formed in a substantially linear shape in the axial direction of the bearing hole 12 but may be formed in a spiral shape. Good.
[0049]
Further, the circumferential groove 23 formed in the bearing bush 22 is a spiral within a range that does not open to both ends of the bearing bush, and preferably within a dimension range of about 1/3 or less of the axial length of the bearing bush. It may be formed in a shape or meandering.
[0050]
【The invention's effect】
As described above in detail, according to the present invention, a stable lubricating oil film is formed between the drive shaft and the bearing bush, and a hydraulic pump that does not cause poor lubrication can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a hydraulic pump showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a drawing showing a developed state of a bearing bush.
FIG. 4 is a cross-sectional view of the bump body in a state where a bearing bush is inserted into the bearing hole.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pump body 2 Pump cover 3 Pump unit 12 Bearing hole 13 Seal chamber 14 Oil groove 22 Bearing bush 23 Recessed groove 24 Oil hole 25 Drive shaft

Claims (3)

A pump unit is accommodated between a pump body having a bearing hole formed therethrough and a pump cover, and a drive shaft for driving the pump unit and a bearing bush for bearing the drive shaft are inserted into the bearing hole. In the hydraulic pump in which a seal chamber is formed at the end of the bearing hole,
While opening between the bearing hole and the bearing bush, and communicating with the seal chamber from the pump unit side, forming an oil groove for flowing the working oil for lubrication,
On the inner peripheral side of the bearing bush, a circumferential groove is formed at a substantially central portion in the axial direction of the bearing bush, and
A hydraulic pump characterized in that an oil hole communicating with the oil groove is formed at the bottom of the concave groove.   2. The hydraulic pump according to claim 1, wherein the groove formed in the bearing bush is formed within a size range of approximately ３ or less of an axial length of the bearing bush. 2. The hydraulic pump according to claim 1, wherein a bearing surface in which no oil groove is formed is formed on an inner peripheral side of the bearing bush and on both axial ends of the concave groove. .

Images