U.S. patent application number 14/134157 was filed with the patent office on 2014-06-26 for hydraulic pump for excavator and excavator comprising the same.
The applicant listed for this patent is Bosch Rexroth (Beijing) Hydraulic Co., Ltd.. Invention is credited to Sheng Lin, Ralf Scharffenberg.
Application Number | 20140178226 14/134157 |
Document ID | / |
Family ID | 50479945 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140178226 |
Kind Code |
A1 |
Scharffenberg; Ralf ; et
al. |
June 26, 2014 |
HYDRAULIC PUMP FOR EXCAVATOR AND EXCAVATOR COMPRISING THE SAME
Abstract
A hydraulic pump for an excavator, which comprises a housing
having a supporting wall extending therein; a pair of rotary
hydraulic cylinders provided in the housing, each of the rotary
hydraulic cylinders being provided with a piston which is movable
reciprocatingly in the rotary hydraulic cylinder; and a pair of
spindles disposed parallel to the rotary hydraulic cylinders, the
spindles being connected with each other via a coupler and driving
the rotary hydraulic cylinders to rotate about their respective
central axes, each of the rotary hydraulic cylinders comprising a
swash plate for receiving and guiding the piston, and the swash
plate being stationary relative to the respective spindle, wherein
the supporting wall comprises a mounting hole, and the coupler is
supported in the mounting hole by means of a sliding bearing.
Inventors: |
Scharffenberg; Ralf;
(Unterjettingen, DE) ; Lin; Sheng; (Beijing,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bosch Rexroth (Beijing) Hydraulic Co., Ltd. |
|
|
|
|
|
Family ID: |
50479945 |
Appl. No.: |
14/134157 |
Filed: |
December 19, 2013 |
Current U.S.
Class: |
417/463 |
Current CPC
Class: |
F04B 1/22 20130101; F04B
1/2071 20130101; F04B 1/324 20130101; F04B 1/20 20130101; F04B
39/0284 20130101 |
Class at
Publication: |
417/463 |
International
Class: |
F04B 1/20 20060101
F04B001/20; F04B 39/02 20060101 F04B039/02; F04B 1/32 20060101
F04B001/32 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2012 |
CN |
2012 105 59108.5 |
Claims
1. A hydraulic pump for an excavator comprising: a housing having a
supporting wall extending therein; a pair of rotary hydraulic
cylinders provided in the housing, each of the rotary hydraulic
cylinders being provided with a respective piston which is movable
reciprocatingly in the rotary hydraulic cylinder; and a pair of
spindles disposed parallel to the rotary hydraulic cylinders, the
spindles being connected with each other via a coupler and driving
the rotary hydraulic cylinders to rotate about respective central
axes, each of the rotary hydraulic cylinders comprising a swash
plate for receiving and guiding the respective piston, and the
swash plate being stationary relative to the respective spindle,
wherein the supporting wall comprises a mounting hole, and the
coupler is supported in the mounting hole by means of a sliding
bearing.
2. The hydraulic pump according to claim 1, further comprising an
adapting bushing, wherein the sliding bearing is mounted in the
mounting hole via the adapting bushing so that the adapting bushing
is located between an outer circumferential surface of the sliding
bearing and an inner surface of the mounting hole.
3. The hydraulic pump according to claim 2, wherein a
circumferential flange extends out radially from an outer
circumferential surface of the adapting bushing near an end of the
adapting bushing which is adjacent to a surface of the supporting
wall, and the circumferential flange is configured for contacting
with the supporting wall.
4. The hydraulic pump according to claim 3, wherein the sliding
bearing is configured as a pair of sliding bearings axially spaced
from each other.
5. The hydraulic pump according to claim 4, wherein the adapting
bushing is configured as a pair of adapting bushings axially spaced
from each other.
6. The hydraulic pump according to claim 5, wherein the supporting
wall is formed with an oil guiding hole, and the oil guiding hole
is aligned with and communicated with an axial gap between the
adapting bushings.
7. The hydraulic pump according to claim 6, wherein the oil guiding
hole is configured for receiving oil leaked in running of the
rotary hydraulic cylinders, so that the leaked oil can pass by the
sliding bearing and flow out via the oil guiding hole after cooling
the bearings.
8. The hydraulic pump according to claim 2, wherein at least one of
the sliding bearing and the adapting bushing is provided with
chamfers at opposite ends.
9. The hydraulic pump according to claim 2, wherein the adapting
bushing is made of an alloy steel material, and the sliding bearing
is made of a powder metallurgy material.
10. The hydraulic pump according to claim 1, wherein a pair of
spherical splines are mounted between the coupler and the
spindles.
11. The hydraulic pump according to claim 7, wherein at least one
of the sliding bearing and the adapting bushing is provided with
chamfers at opposite ends.
12. The hydraulic pump according to any claim 11, wherein the
adapting bushing is made of an alloy steel material, and the
sliding bearing is made of a powder metallurgy material.
13. The hydraulic pump according to claim 12, wherein a pair of
spherical splines are mounted between the coupler and the
spindles.
14. An excavator comprising a hydraulic pump according to claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hydraulic pump, in
particular to a hydraulic pump for an excavator, and to an
excavator comprising the hydraulic pump.
BACKGROUND ART
[0002] A hydraulic pump used in an excavator generally comprises a
housing and a pair of rotary hydraulic cylinders accommodated in
the housing. The rotary hydraulic cylinders are disposed coaxially
opposite to each other. A driving shaft is supported in the housing
parallel to longitudinal axes of the rotary hydraulic cylinders.
Two swath plates are mounted in the housing fixedly relative to the
driving shaft. In the rotary hydraulic cylinder there is provided
with a reciprocating piston. Each of the swash plates comprises a
mating surface for receiving and guiding the piston. Each of the
rotary hydraulic cylinders is driven to rotate about a central axis
of the driving shaft, and thus the piston is driven to move
reciprocatingly in the respective rotary hydraulic cylinder as the
driving shaft rotates.
[0003] In the prior art, in order to reduce manufacturing and
assembly cost, the driving shaft mentioned above is configured as
two separate spindles which are disposed coaxially with each other
and have substantially the same length, the two spindles being
connected with each other via a coupler. A needle bearing for
supporting purpose is provided substantially in the middle of the
driving shaft and therefore at the coupler because the driving
shaft formed by connecting via the coupler is long, which provides
sufficient support to the driving shaft and prevents the driving
shaft from bending and deforming caused by the long driving shaft
consisting of the coupler.
[0004] On one hand, the needle bearing has a relative precise
structure, and on the other hand, the excavator generally works
under bad conditions. This causes a loud noise to be generated
during the running of the needle bearing in the hydraulic pump and
causes a high failure possibility. The hydraulic pump works at a
low work efficiency and may even be damaged, and then the service
life of the excavator is affected and its maintenance period is
shortened.
[0005] It is thus desired to improve the bearing of the hydraulic
pump in term of its service life and to reduce the failure
possibility of the bearing, in order to improve the work efficiency
of the hydraulic pump and to prolong the service life of the
excavator or the maintenance period.
[0006] In addition, the swash plates may be disposed at an angle
relative to the driving shaft depending on the work conditions, and
a certain bending moment or a centrifugal force can then be
generated (the reasons will be described in the following
description) at the coupler when the driving shaft is driven to
rotate. Excessive bending moment or centrifugal force may cause an
excessive vibration on the driving shaft, and then the efficiency
of the hydraulic pump will be affected.
[0007] It is thus desired to decrease the bending moment as
possible as it can by improving the hydraulic pump, to reduce the
vibration of the driving shaft and thus improve the efficiency of
the hydraulic pump.
SUMMARY OF THE INVENTION
[0008] An object of the invention is to provide a hydraulic pump
and an excavator comprising the hydraulic pump, which have
prolonged service life and reduced manufacturing cost, to reduce
vibration of a driving shaft in the hydraulic pump and to improve
efficient of the hydraulic pump.
[0009] According to one aspect of the invention, a hydraulic pump
for an excavator is provided, which comprises a housing having a
supporting wall extending therein; a pair of rotary hydraulic
cylinders provided in the housing, each of the rotary hydraulic
cylinders being provided with a piston which is movable
reciprocatingly in the rotary hydraulic cylinder; and a pair of
spindles disposed parallel to the rotary hydraulic cylinders, the
spindles being connected with each other via a coupler and driving
the rotary hydraulic cylinders to rotate about their respective
central axes, each of the rotary hydraulic cylinders comprising a
swash plate for receiving and guiding the piston, and the swash
plate being stationary relative to the respective spindle, wherein
the supporting wall comprises a mounting hole, and the coupler is
supported in the mounting hole by means of a sliding bearing.
According to the above technical solution of the invention, the
sliding bearing has a relative simple structure, a more impact
resistant property, a significantly prolonged service life, and a
reduced manufacturing cost, and the noise generated during its
running is low. Optionally, the swash plate has an adjustable angle
relative to the spindle to adjust an amount of a stroke of the
piston in the rotary hydraulic cylinder.
[0010] Preferably, the hydraulic pump is provided with an adapting
bushing therein, and the sliding bearing is mounted in the mounting
hole via the adapting bushing so that the adapting bushing is
located between an outer circumferential surface of the sliding
bearing and an inner surface of the mounting hole. The adapting
bushing is made of a material different from that of the sliding
bearing. For example, the adapting bushing is made of a steel
material, in particular an alloy steel material, while the sliding
bearing is made of a powder metallurgy material. Accordingly, the
sliding bearing is not directly mounted in the mounting hole of the
supporting wall, but via the adapting bushing, which results in the
wear to the housing itself being reduced and the service life of
the hydraulic pump being prolonged.
[0011] Preferably, a circumferential flange extends out radially
from an outer circumferential surface of the adapting bushing near
an end of the adapting bushing which is adjacent to a surface of
the supporting wall, and the circumferential flange is configured
for contacting with the supporting wall. The circumferential flange
is configured for fixing the adapting bushing into position,
preventing the adapting bushing from being displaced during
mounting or after mounting and thus ensuring the normal work of the
sliding bearing.
[0012] Preferably, the sliding bearing is configured as a pair of
sliding bearings axially spaced from each other; and/or the
adapting bushing is configured as a pair of adapting bushings
axially spaced from each other. In this way, heat generated during
the running of the hydraulic pump and in particular during the
rotating of the coupler can be dissipated more rapidly, and the
temperature of the sliding bearings is reduced. In addition, the
manufacturing cost is reduced accordingly because the material from
which the sliding bearings and/or the adapting bushings are
manufactured is expensive. This also results in a smaller bending
moment generated at the bearing during the running of the hydraulic
pump (details will be described in the following), and thus the
vibration generated on the spindle is reduced or even eliminated.
The work efficiency of the hydraulic pump is therefore
improved.
[0013] Preferably, the supporting wall is formed with an oil
guiding hole, and the oil guiding hole is aligned with and
communicated with an axial gap between the adapting bushings.
Lubricant oil can be injected into the axial gap via the oil
guiding hole to lubricate the bearing and cool the sliding bearing
when the spindle rotates. It is conceivable that the oil guiding
hole can be configured for receiving oil leaked in the running of
the rotary hydraulic cylinders, so that the leaked oil can pass by
the sliding bearing and flow out via the oil guiding hole after
cooling the bearings.
[0014] Preferably, the sliding bearing is provided with chamfers at
opposite ends, so that the sliding bearing can be easily inserted
into the mounting hole or into the adapting bushing when
assembling, and lubricant oil can reach the sliding bearing more
easily to achieve a good lubricant effect.
[0015] Preferably, the adapting bushing is provided with chamfers
at opposite ends and preferably out-chamfers, so that the adapting
bushing can be inserted into the mounting hole easily.
[0016] Preferably, a pair of spherical splines are amounted between
the coupler and the spindles. According to another aspect of the
invention, an excavator comprising the hydraulic pump described
above is provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above and other aspects of the invention will be better
understood from the following description in conjunction with the
drawings, in which:
[0018] FIG. 1 shows an axial cross-sectional view of a hydraulic
pump according to one illustrative embodiment of the invention;
[0019] FIG. 2 shows an enlarged view of a portion of the hydraulic
pump shown in FIG. 1;
[0020] FIG. 3 shows an axial cross-sectional view of a hydraulic
pump according to another illustrative embodiment of the
invention;
[0021] FIG. 4 shows an enlarged view of a portion of the hydraulic
pump shown in FIG. 3; and
[0022] FIG. 5 is similar to FIG. 4, showing an enlarged view of a
portion of a hydraulic pump according to a further illustrative
embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0023] Illustrative embodiments of the invention will be described
with reference to the drawings. It should be noted that same
reference numbers throughout the drawings denote functionally
and/or structurally identical elements or devices.
[0024] FIG. 1 shows an axial cross-sectional view of a hydraulic
pump 1 according to one embodiment of the invention. The hydraulic
pump according to the invention can be used in a mechanical device
working in bad conditions, for example in an excavator.
[0025] As shown in FIG. 1, the hydraulic pump 1 comprises a housing
2 and end caps 3 and 4 mounted on opposite ends of the housing 2.
Two spindles 5 and 6, two rotary hydraulic cylinders 9 and 10, and
two swash plates 7 and 8 for driving the rotary hydraulic cylinders
are provided in the housing 2. The swash plates 7 and 8 are
configured for adjusting working strokes of the rotary hydraulic
cylinders 9 and 10 respectively.
[0026] The two spindles 5 and 6 are disposed coaxially and are
connected with each other at their opposite ends via a coupler 13
in a known way. In the illustrated embodiment, the spindle 5
comprises an end which extends out of the end cap 3 to be connected
with a driving device, for example, a diesel engine (not shown), so
that the two spindles 5 and 6 can be driven by the driving device
to rotate.
[0027] For example, the swash plate 7 is mounted on the end cap 3
fixedly relative to the housing 2, and for example, the swash plate
8 is mounted on the end cap 4 fixedly relative to the housing 2.
The swash plates 7 and 8 comprise central openings respectively,
and the central openings are sized such that the spindles 5 and 6
can pass through the central openings respectively without
contacting with them.
[0028] The rotary hydraulic cylinders 9 and 10 are arranged
substantially parallel to the spindles 5 and 6, and are connected
with the spindles 5 and 6 via spline structures 26 and 27
respectively. A piston 11 is provided to be slidable in the rotary
hydraulic cylinder 9, and a piston 12 is provided to be slidable in
the rotary hydraulic cylinder 10. The pistons 11 and 12 are
provided with piston heads 11 a and 12a at their ends respectively
to be mated with sliding shoes 24 and 25 respectively.
[0029] The swash plates 7 and 8 comprise guiding and mating
surfaces for guiding sliding shoes 24 and 25 respectively. The
rotary hydraulic cylinders 9 and 10 are driven by the spindles 5
and 6 to rotate about central axes of the spindles respectively
together with their pistons 11 and 12 during the running of the
hydraulic pump. Because the sliding shoes 24 and 25 remains always
contact with the corresponding guiding and mating surfaces of the
swash plates 7 and 8, the pistons 11 and 12 can be slided axially
and reciprocatingly in the rotary hydraulic cylinders 9 and 10. The
rotary hydraulic cylinders 9 and 10 comprise their own separate
outlets respectively, so that the moving pistons 11 and 12 supply
hydraulic oil for hydraulic operating components of the excavator
one independent of another.
[0030] Angles of inclination of the swash plates 7 and 8 relative
to the spindles 5 and 6 are adjustable, so that reciprocating
strokes of the pistons 11 and 12 in the rotary hydraulic cylinders
9 and 10 can be adjusted accordingly. For example, the swash plate
7 is shown, in the left of FIG. 1, to be at a larger angle of
inclination relative to an axis perpendicular to the spindle 5 to
set the maximum reciprocating stroke of the piston 11 in the rotary
hydraulic cylinder 9; and the swash plate 8 is shown, in the right
of FIG. 1, to be at a smaller angle of inclination relative to an
axis perpendicular to the spindle 6 to set the minimum
reciprocating stroke of the piston 12 in the rotary hydraulic
cylinder 10.
[0031] With reference to FIG. 2, a sliding bearing 14 is provided
in the housing 2 which is configured for providing sufficient
support for the spindles 5 and 6. The sliding bearing can be
configured as an integral or split bearing bush made of any
suitable wear resistant metal material, such as a bearing alloy or
powder metallurgy material. The sliding bearing 14 is disposed over
the coupler 13 with an inner circumferential surface of the sliding
bearing 14 in contact with an outer circumferential surface of the
coupler 13.
[0032] The housing 2 comprises a supporting wall 2a, and the
supporting wall 2a is provided with a mounting hole for mounting
the bearing 14 therein.
[0033] As shown in FIG. 2, preferably, the sliding bearing 14 is
mounted in the mounting hole via an adapting bushing 15 in order to
protect the supporting wall 2a and improve service life of the
sliding bearing 14. Preferably, the sliding bearing 14 and the
adapting bushing 15 have substantially the same longitudinal
length, and their longitudinal lengths are greater than the
thickness of the supporting wall 2a in a direction of the central
axes of the spindles 5 and 6.
[0034] As can be seen from FIG. 1, a majority of the spindle 5, the
swash plate 7 and the rotary hydraulic cylinder 9 are at the left
side of the supporting wall 2a, while a majority of the spindle 6,
the swash plate 8 and the rotary hydraulic cylinder 10 are at the
right side of the supporting wall 2a. Preferably, the two rotary
hydraulic cylinders 9 and 10 are disposed coaxially.
[0035] The adapting bushing 15 can be made of a metal material
which is more wear resistant than the housing 2. For example, the
adapting bushing 15 is made of a steel material. Still for example,
the adapting bushing 15 can be made of a material same as or
different from that of the sliding bearing 14. A circumferential
flange 15a extends out radially from an outer circumferential
surface of the adapting bushing 15 near an end (for example, the
left end in FIG. 2) of the adapting bushing 15 for the purpose of
positioning. The circumferential flange 15a is configured for
abutting against an end surface of the supporting wall 2a so that
the adapting bushing 15 can be fixed into position.
[0036] Upon mounting into position, an inner circumferential
surface of the adapting bushing 15 is in contact with an outer
circumferential surface of the sliding bearing 14, while the outer
circumferential surface of the adapting bushing 15 is in contact
with a surface of the mounting hole in the supporting wall 2a. For
a mechanical device working in bad conditions, such as an
excavator, a hydraulic pump according to the invention incorporates
the sliding bearing so that the structure becomes simpler and the
enduring ability for heavy loads is improved. The service life of
hydraulic pump is significantly prolonged and the manufacturing
cost is reduced. In addition, according to the technical solutions
of the invention, the sliding bearing 14 can be mounted in the
housing of hydraulic pump via the adapting bushing 15, and the wear
to the housing 2 itself is therefore reduced and the service life
of the hydraulic pump is improved accordingly.
[0037] FIG. 3 and FIG. 4 show a hydraulic pump according to another
illustrative embodiment of the invention. This hydraulic pump
differs from the previous embodiment in that the coupler 13
comprises a pair of sliding bearings 18 and 19 which are spaced
from each other axially and mounted on the coupler 13. The sliding
bearings 18 and 19 can be made of the same material as the sliding
bearing 14 shown in FIG. 1.
[0038] Due to the sliding bearings 18 and 19 spaced axially, heat
generated during the running of the hydraulic pump and in
particular during the rotating of the coupler 13 can be dissipated
more rapidly, and the temperature of the sliding bearings is
reduced significantly. The sliding bearings 18 and 19 have
substantially the same axial length and are disposed over the
coupler 13, so that inner circumferential surfaces of the sliding
bearings 18 and 19 are in contact with the outer circumferential
surface of the coupler 13. As can be seen from FIG. 4, the sliding
bearings 18 and 19 are spaced from each other sysmetrically with
reference to a mid plane L of the coupler 13 which is perpendicular
to the coupler 13.
[0039] Similar to the previous embodiment, the sliding bearings 18
and 19 are provided with adapting bushings 16 and 17 respectively
via which the sliding bearings 18 and 19 are mounted in the
mounting hole in the supporting wall 2a of the housing 2. As shown
in FIG. 4, the two adapting bushings 16 and 17 may have same axial
lengths as the sliding bearings 18 and 19 and extend over the
sliding bearings 18 and 19. Upon mounting into position, inner
circumferential surfaces of the adapting bushings 16 and 17 are in
contact with outer circumferential surfaces of the sliding bearings
18 and 19.
[0040] The adapting bushings 16 and 17 and the adapting bushings 15
may be manufactured from the same material. Circumferential flanges
16a and 17a extend out radially from outer circumferential surfaces
of the adapting bushings 16 and 17 near ends of the adapting
bushings 16 and 17 approximate to the corresponding end surfaces of
the supporting wall 2a, also for the purpose of the positioning.
The circumferential flanges 16a and 17a are configured for abutting
against the corresponding end surfaces of the supporting wall 2a so
that the adapting bushings 16 and 17 can be fixed into
position.
[0041] It can be found when comparing FIG. 2 with FIG. 4, for the
couplers 13 with the same axial length, through manufacturing the
sliding bearing of the invention as two sliding bearings 18 and 19
axially spaced from each other and/or manufacturing the adapting
bushing of the invention as two sliding bushings 16 and 17 axially
spaced from each other, the material from which they are
manufactured can be saved. This reduces the manufacturing cost
accordingly because the material from which the sliding bearings
and/or the adapting bushings are manufactured is expensive.
[0042] As shown in FIG. 3, by way of the left swash plate 7 as an
example, the swash plate 7 is stationary relative to the spindle 5
during the running of the hydraulic pump, the rotary hydraulic
cylinder 9 is driven by the spindle 5 to rotate about its central
axis, and at the same time the piston 11 moves reciprocatingly in
the rotary hydraulic cylinder 9. It can be known from theoretically
technical analysis known in the prior art, an action point O of a
resultant force the rotary hydraulic cylinder 9 applies upon the
spindle 5 is situated on the central axis of the spindle 5.
[0043] The sliding bearing 18 has a center of gravity G, and the
axial length from the center of gravity G to the action point O of
the resultant force is A. A bending moment will be generated at the
area in which the bearing is contacted with the mounting hole
during the running of the hydraulic pump. Excessive bending moment
may cause the spindle to vibrate or even destabilize, and so affect
the work efficiency of the hydraulic pump. It can known from the
theoretical calculation that the amount of the bending moment
depends on the distance between the center of gravity of the
sliding bearing and the action point O of the resultant force. The
smaller the distance is, the smaller the bending moment generated
during the running of the hydraulic pump is, and then the smaller
the vibration is.
[0044] FIG. 3 shows a center of gravity G' of the coupler 13. For
the sliding bearing 14 shown in FIG. 1, the center of gravity of
the sliding bearing 14 is consistent with the center of gravity G'
of the coupler 13. That is to say, the distance between the center
of gravity of the sliding bearing 14 shown in FIG. 1 and the action
point O of the resultant force is A'. It can be clearly seen from
FIG. 3 that the distance A is smaller than the distance A' because
the sliding bearings 18 and 19 are disposed over the coupler 13
with one spaced from each another. Consequently, compared with the
embodiment shown in FIG. 1, the hydraulic pump according to the
embodiment shown in FIG. 3 has a smaller bending moment generated
at the bearing during running, and thus the vibration generated on
the spindle is smaller or even eliminated. The work efficiency of
the hydraulic pump is improved.
[0045] The same also applies to the right swash plate 8, the
spindle 6, the rotary hydraulic cylinder 10 and the piston 12 shown
in FIG. 3.
[0046] FIG. 5 shows a hydraulic pump according to a further
embodiment of the invention. The supporting wall 2a is formed with
a through hole 20 therein which extends in a direction
perpendicular to the central axes of the spindles 5 and 6. The
through hole 20 is aligned with and communicated with a gap between
the sliding bearings 18 and 19 so that lubricant oil can be
injected into the gap to lubricate the bearings and at the same
time to lower the temperature of the sliding bearings 18 and 19
when the spindles 5 and 6 rotate. It is conceivable that the
through hole 20 can be further configured for receiving the oil
leaked from the rotary hydraulic cylinders 9 and 10 during their
running. In this way, the received oil can pass by the sliding
bearings 18 and 19, cause the temperature of the bearings to be
lowered, and then flows out of the through hole.
[0047] In another embodiment, a pair of spherical splines are
mounted between the coupler 13 and the spindles 5, 6.
[0048] Optionally, in order to further improve lubricating and
temperature decreasing effect, a plurality of through holes 20 can
be provided in the supporting wall 2a, which extend perpendicularly
to the central axes of the spindles 5 and 6, and all the through
holes 20 are aligned and communicated with the gap between the
sliding bearings 18 and 19. In addition, optionally, the through
hole 20 may be arranged at another angle with reference to the
central axes of the spindles 5 and 6.
[0049] To facilitate assembling, as shown in FIGS. 2, 4 and 5, the
sliding bearings 14, 18 and 19 are manufactured preferably with
chamfers at outer surfaces of opposite ends respectively, so that
the sliding bearings can be inserted into the adapting bushings 15
and 17 smoothly when assembling, and the lubricant oil can enter
the areas between the sliding bearings and the mating components
around more easily.
[0050] Although in the above embodiments the sliding bearing 14 or
the sliding bearings 18 and 19 according to the invention is/are
shown to support the coupler 13 between the two spindles 5 and 6,
it is conceivable that, in a case that the swash plates 7 and 8 in
the hydraulic pump are only driven by a single spindle, the sliding
bearing 14 or the sliding bearings 18 and 19 according to the
invention may be supported in the mounting hole of the supporting
wall 2a at a substantially central location of the single the
spindle in its longitudinal direction via the adapting bushing 15
or the adapting bushings 16 and 17.
[0051] It is conceivable that, in the embodiment shown in FIG. 4,
the adapting bushings 16 and 17 can be replaced with the adapting
bushing 15; or the sliding bearings 18 and 19 can be replaced with
the sliding bearing 14. It is conceivable that, in the embodiment
shown in FIG. 5, the sliding bearings 18 and 19 can be replaced
with the sliding bearing 14. In addition, it is conceivable that
the axial separation between the adapting bushings 16 and 17 may
also be different from the axial separation between the sliding
bearings 18 and 19.
[0052] Although the sliding bearing 14 or the sliding bearings 18
and 19 is/are configured for supporting the coupler 13 in the
supporting wall 2a inside the housing 2 in the embodiments of the
invention, it is conceivable that the sliding bearing 14 or the
sliding bearings 18 and 19 may also be configured as bearings in
the end cap 3 and/or the end cap 4 for supporting the spindle 5
and/or the spindle 6.
[0053] It is conceivable that, in a case that N (in which N is an
integer larger than 2) spindles are provided coaxially in a
hydraulic pump and are connected via N-1 couplers, the sliding
bearing 14 or the sliding bearings 18 and 19 may be provided at
locations of the N-1 couplers respectively for supporting the
respective spindles.
[0054] According to the invention, a sliding bearing with a
relative simple structure is incorporated into a hydraulic pump,
which results in an improved stress distribution, a prolonged
service life of the hydraulic pump, and at the same time reduced
manufacturing and assembly cost. In addition, through providing the
sliding bearings spaced from each other axially, heat generated
during the running of a spindle can be dissipated efficiently, the
working temperature of the bearing can be reduced, and thus the
failure risk is avoided. Through providing an oil guiding hole in a
housing of the hydraulic pump which is aligned and communicated
with a gap between the sliding bearings, the bearing can be
lubricated efficiently and the heat generated during the rotation
can be taken away efficiently. This may further reduce the working
temperature of the bearing.
[0055] Although special embodiments of the invention have been
described above, they are presented only for illustration purpose
and not intended to limit the scope of the invention. Rather,
various substitutions, variants and changes can be conceived
without departing from the spirit and scope of the invention.
* * * * *