U.S. patent application number 12/264787 was filed with the patent office on 2010-05-06 for three speed floating cup hydraulic motor.
This patent application is currently assigned to Caterpillar Inc.. Invention is credited to Bryan E. Nelson.
Application Number | 20100107866 12/264787 |
Document ID | / |
Family ID | 42129870 |
Filed Date | 2010-05-06 |
United States Patent
Application |
20100107866 |
Kind Code |
A1 |
Nelson; Bryan E. |
May 6, 2010 |
Three speed floating cup hydraulic motor
Abstract
A hydraulic motor includes a rotor supporting a plurality of
piston elements projecting away from opposing faces of the rotor.
The rotor is adapted to rotate about a first axis. The hydraulic
motor further includes a pair of drum plates each supporting a
plurality of cup elements. The plurality of cup elements are
adapted to engage the piston elements. Each drum plate is arranged
on an opposing side of the rotor and is adapted to rotate about a
second axis in angled relation to the first axis. Each of a pair of
swashplates is in operative engagement with a respective one of the
drum plates and each is adapted to pivot relative to the rotor to
move with the respective drum plate between a maximum displacement
position and a minimum displacement position to thereby change the
angled relation between the first axis and the second axis. The
pair of swashplates are further independently pivotable between
three different settings.
Inventors: |
Nelson; Bryan E.; (Lacon,
IL) |
Correspondence
Address: |
LEYDIG, VOIT & MAYER, LTD
TWO PRUDENTIAL PLAZA SUITE 4900, 180 N. STETSON AVE
CHICAGO
IL
60601
US
|
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
42129870 |
Appl. No.: |
12/264787 |
Filed: |
November 4, 2008 |
Current U.S.
Class: |
91/506 ; 417/270;
417/271 |
Current CPC
Class: |
F04B 1/22 20130101 |
Class at
Publication: |
91/506 ; 417/270;
417/271 |
International
Class: |
F04B 1/22 20060101
F04B001/22; F04B 1/24 20060101 F04B001/24; F04B 1/32 20060101
F04B001/32; F01B 3/02 20060101 F01B003/02 |
Claims
1. A hydraulic motor comprising: a rotor supporting a plurality of
piston elements projecting away from opposing faces of the rotor,
the rotor being adapted to rotate about a first axis; a pair of
drum plates each supporting a plurality of cup elements, the
plurality of cup elements being adapted to engage the piston
elements, each drum plate being arranged on an opposing side of the
rotor and being adapted to rotate about a second axis in angled
relation to the first axis; a pair of swashplates each being in
operative engagement with a respective one of the drum plates, each
swashplate being adapted to pivot relative to the rotor so as to
move with the respective drum plate between a maximum displacement
position and a minimum displacement position to thereby change the
angled relation between the first axis and the second axis, wherein
the pair of swashplates are independently pivotable between a first
setting in which both swashplates are in their maximum displacement
position, a second setting in which both swashplates in their
minimum displacement position and a third setting in which one
swashplate is in its maximum displacement setting and the other
swashplate is in its minimum displacement setting.
2. The hydraulic motor of claim 1 further including an output shaft
connected to the rotor and extending along the first axis.
3. The hydraulic motor of claim 2 further including an actuating
system operable to independently pivot the pair of swashplates
between the first setting, the second setting and the third
setting.
4. The hydraulic motor of claim 3 wherein the actuating system is
hydraulically actuated.
5. The hydraulic motor of claim 4 wherein the actuating system
includes at least one actuator associated with each swashplate that
is operable in response to a control signal to pivot the
corresponding swashplate.
6. The hydraulic motor of claim 5 wherein the actuating system
further includes a control signal generator operably coupled to the
at least one actuator associated with each swashplate for
generating the control signal for the actuators.
7. The hydraulic motor of claim 5 wherein the actuating assembly
further includes a spring in operative engagement with both of the
swashplates for biasing the swashplates toward one of their maximum
displacement and minimum displacement positions.
8. The hydraulic motor of claim 7 wherein the at least one actuator
associated with each swashplate is operable to pivot the
swashplates toward the other of their maximum displacement and
minimum displacement positions.
9. The hydraulic motor of claim 6 wherein the at least one actuator
associated with each swashplate comprises a piston and cup
assembly.
10. The hydraulic motor of claim 6 wherein the control signal
produced by the control signal generator comprises a supply of
pressurized fluid.
11. A hydraulic motor comprising: a rotor supporting a plurality of
piston elements projecting away from opposing faces of the rotor,
the rotor being adapted to rotate about a first axis; a pair of
drum plates each supporting a plurality of cup elements, the
plurality of cup elements being adapted to engage the piston
elements, each drum plate being arranged on an opposing side of the
rotor and being adapted to rotate about a second axis in angled
relation to the first axis; a pair of swashplates each being in
operative engagement with a respective one of the drum plates, each
swashplate being adapted to pivot relative to the rotor so as to
move with the respective drum plate between a maximum displacement
position and a minimum displacement position to thereby change the
angled relation between the first axis and the second axis; an
actuating system operable to independent pivot the pair of
swashplates between a first setting in which both swashplates are
in their maximum displacement position, a second setting in which
both swashplates in their minimum displacement position and a third
setting in which one swashplate is in its maximum displacement
setting and the other swashplate is in its minimum displacement
setting.
12. The hydraulic motor of claim 11 further including an output
shaft connected to the rotor and extending along the first
axis.
13. The hydraulic motor of claim 11 wherein the actuating system is
hydraulically actuated.
14. The hydraulic motor of claim 11 wherein the actuating system
includes at least one actuator associated with each swashplate that
is operable in response to a control signal to pivot the
corresponding swashplate.
15. The hydraulic motor of claim 14 wherein the actuating system
further includes a control signal generator operably coupled to the
at least one actuator associated with each swashplate for
generating the control signal for the actuators.
16. The hydraulic motor of claim 15 wherein the actuating assembly
further includes a spring in operative engagement with both of the
swashplates for biasing the swashplates toward one of their maximum
displacement and minimum displacement positions.
17. The hydraulic motor of claim 16 wherein the at least one
actuator associated with each swashplate is operable to pivot the
swashplates toward the other of their maximum displacement and
minimum displacement positions.
18. The hydraulic motor of claim 14 wherein the at least one
actuator associated with each swashplate comprises a piston and cup
assembly.
19. A method of operating a hydraulic motor comprising the steps
of: introducing sequentially a fluid at an intake pressure into a
plurality of cup elements supported on a pair of drum plates, the
plurality of cup elements being adapted to engage a plurality of
piston elements supported on a rotor with piston elements
projecting away from opposing faces of the rotor which is adapted
to rotate about a first axis, each drum plate being arranged on an
opposing side of the rotor and being adapted to rotate about a
second axis in angled relation to the first axis; discharging the
fluid from the plurality of cup elements at a discharge pressure
which is lower than the intake pressure; pivoting independently a
pair of swashplates relative to the rotor between a maximum
displacement position and a minimum displacement position, each
swashplate being in operative engagement with a respective one of
the drum plates such that each drum plate moves with the respective
swashplate between the maximum and minimum displacement positions
to thereby change the angled relation between the first and second
axes; and selectively directing pivoting movement of the pair of
swashplates into a first setting in which both swashplates are in
their maximum displacement position, a second setting in which both
swashplates in their minimum displacement position or a third
setting in which one swashplate is in its maximum displacement
setting and the other swashplate is in its minimum displacement
setting.
20. The method of claim 19 further including the step of
transmitting rotation of the rotor to an output shaft that extends
along the first axis.
Description
TECHNICAL FIELD
[0001] This patent disclosure relates generally to hydraulic motors
and, more particularly to floating cup hydraulic motors.
BACKGROUND
[0002] Hydraulic motors can be used to propel a variety of
machines, e.g., loaders, excavators, dozers and the like. To
provide two different operating speeds, the piston pumps in
conventional hydraulic motors may use a simple toggle to switch a
swashplate angle between maximum and minimum displacement settings.
The maximum displacement setting may provide relatively low speed
and high torque, while the minimum displacement setting may provide
relatively high speed and low torque.
[0003] Conventional hydraulic motors utilize piston pumps with
five, seven or nine pistons. As a result, starting torque of the
motor can be quite low. Hydraulic motors utilizing a so-called
floating cup type pump can provide higher initial starting torque
than conventional hydraulic motors. A hydraulic motor based on a
floating cup type pump is disclosed in International Patent
Publication No. WO 2006/094990-A1 in the name of Achten, having a
publication date of Sep. 14, 2006. The disclosed floating cup type
pump generally utilizes a plurality of piston elements projecting
away from either side of a rotor.
[0004] The pumps described in this reference include a centrally
disposed rotor having a plurality of pistons projecting away from
both sides of the rotor. A pair of cooperating drum plates disposed
outboard from the rotor support an arrangement of cup elements or
drum sleeves adapted to house distal portions of the pistons. The
rotor supporting the pistons rotates around a first axis of
rotation. The drum plates rotate in angled relation to the first
axis. The rotor supporting the pistons is rotated in tandem with
the drum plates during operation. Due to the angle between the
rotor and the drum plates, the cups are caused to stroke along the
length of the corresponding piston elements such that the volume
occupied by the piston elements is alternately increased and
decreased during the rotational cycle. Thus, fluid introduced into
a cup element when the complementary piston is in a substantially
withdrawn position may be pressurized and expelled as the cup is
pushed inwardly during the rotational cycle. The reference
discloses infinitely varying the displacement of the pump by
varying the angle of a swashplate that is disposed axially outward
of the drum plate between a zero angle and a maximum angle.
However, the reference does not disclose providing the pump with a
discrete set of displacement settings.
SUMMARY
[0005] The disclosure describes, in one aspect, a hydraulic motor.
The hydraulic motor includes a rotor supporting a plurality of
piston elements projecting away from opposing faces of the rotor.
The rotor is adapted to rotate about a first axis. The hydraulic
motor further includes a pair of drum plates each supporting a
plurality of cup elements. The plurality of cup elements are
adapted to engage the piston elements. Each drum plate is arranged
on an opposing side of the rotor and is adapted to rotate about a
second axis in angled relation to the first axis. Each of a pair of
swashplates is in operative engagement with a respective one of the
drum plates. Each swashplate is adapted to pivot relative to the
rotor with the respective drum plate between a maximum displacement
position and a minimum displacement position to thereby change the
angled relation between the first axis and the second axis. The
pair of swashplates are independently pivotable between a first
setting in which both swashplates are in their maximum displacement
position, a second setting in which both swashplates in their
minimum displacement position and a third setting in which one
swashplate is in its maximum displacement setting and the other
swashplate is in its minimum displacement setting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a cutaway schematic perspective view illustrating
the components of an exemplary floating cup hydraulic motor.
DETAILED DESCRIPTION
[0007] This disclosure relates to a hydraulic motor. To allow for
greater torque at start-up of the motor, the disclosed hydraulic
motor is based on a floating cup pump. The hydraulic motor may be
powered by any source of pressurized fluid such as, for example, a
hydraulic pump. In different applications, it may be advantageous
that the hydraulic motor be able to operate at different
speeds.
[0008] FIG. 1 illustrates a motor 10 that is mounted within a motor
housing 12. In this exemplary construction, an output shaft 14
extends along and is adapted for rotation about a first axis 16.
The output shaft 14 is adapted for rotation around the first axis
16. The output shaft 14 engages a rotor 18 in the form of a disk or
plate structure. Thus, rotation of the rotor 18 is translated to
the output shaft 14 such that the rotor 18 rotates around the same
axis as the output shaft 14, namely the first axis 16.
[0009] In the exemplary construction illustrated in FIG. 1, the
rotor 18 supports an arrangement of piston elements 20 projecting
away from opposing faces of the rotor 18 so as to define, in this
case, left and right sides of the motor. As shown, the piston
elements 20 may have a generally frusto-conical configuration such
that the piston elements 20 taper outwardly as the distance
increases away from rotor 18. However, other suitable constructions
may likewise be utilized as desired.
[0010] In the illustrated construction of FIG. 1, the motor 10
includes a pair of drum plates 22 disposed on either side of the
rotor 18 in each side of the motor 10. As shown, the drum plates 22
support an arrangement of cup elements 24 having open ends that
project towards the rotor 18. The cup elements 24 are arranged to
house distal portions of the complementary piston elements 20. With
this configuration, the cup elements 24 circumferentially surround
distal portions of the corresponding piston elements 20 such that
the piston elements 20 cooperate with interior boundary walls of
the cup elements 24 to define a plurality of variable volume piston
chambers 25.
[0011] The drum plates 22 are arranged in circumferential relation
to the output shaft 14 and are oriented at an angle relative to the
rotor 18. Thus, the drum plates 22 and the cup elements 24
supported thereon are rotatable around axis lines disposed in
angled relation to the first axis 16 of the output shaft 14 and
rotor 18. According to the exemplary construction, the drum plates
22 are supported in this angled orientation by curved surface
support elements 26 which are arranged around the output shaft 14
outboard from the rotor 18. The curved surface support elements 26
include a convex exterior support surface adapted to engage a
portion of the drum plates 22. In the illustrated motor 10, a pair
of swashplates 28 are provided with each being arranged outboard of
and in operative engagement with a corresponding drum plate 22. In
this case, each swashplate 28 is in contacting relation with its
respective drum plate 22.
[0012] Although the motor 10 may be adapted for any number of uses,
according to one contemplated practice, a high pressure fluid flows
into the motor 10 through an intake port 30. Inside the motor 10,
the power of the pressurized fluid is converted into mechanical
energy in the form of rotation of the output shaft 14. The fluid
then exits the motor through a discharge port 32 at a lower
pressure. More specifically, as each piston element 20 and
corresponding cup element 24 assembly passes over the intake port
30, the high pressure fluid enters the piston chamber 25 and causes
the piston element 20 to extend outward relative to the
corresponding cup element 24. The angle of the drum plate 22
relative to the piston element 20 displacement causes the rotor 18
and thereby the output shaft 14 to rotate. As a result of this
rotation, each piston element 20 and cup element 24 assembly
periodically passes over the intake and discharge ports 30, 32.
Thus, the piston elements 20 undergo an oscillatory displacement in
and out relative to their corresponding cup element 24 receiving
high pressure fluid from the intake port 30 and discharging
relatively lower pressure fluid through the discharge port 32.
[0013] During each rotation of the rotor 18, each piston element 20
displaces a certain distance in its corresponding cup element 24.
The angle of the drum plate 22 relative to the rotor 18 and output
shaft 14 determines the magnitude of the displacement of each
piston element 20. In order to allow the displacement of the piston
elements 20 to be varied, each swashplate 28, and with its
corresponding drum plate 22, may be pivotable relative to the rotor
18 and output shaft 14 such that the angle of the swashplate 28 and
drum plate 22 relative to the rotor 18 and output shaft 14, i.e.
the first axis 16, can be changed. Varying the displacement of the
piston elements 20 enables the speed and torque produced at the
output shaft 14 of the motor 10 to be varied.
[0014] In this case, each swashplate 28 may be pivotable between a
maximum displacement position in which the displacement of the
piston elements 20 is maximized and a minimum displacement position
in which the displacement of the piston elements 20 is minimized.
Each of the swashplates 28 is shown in its maximum displacement
position in FIG. 1. To reach the minimum displacement position,
with reference to FIG. 1, the left swashplate 28 pivots clockwise
and the right swashplate 28 pivots counter clockwise. The minimum
displacement position can be any swashplate angle greater than a
zero angle.
[0015] Each of the swashplates 28 may be independently pivotable
with respect to the other swashplate. Accordingly, the disclosed
motor 10 may operate at three different speed settings: A first low
speed, high torque setting in which both swashplates 28 are in
their maximum displacement position; a second high speed, low
torque setting in which both swashplates 28 are in their minimum
displacement position; and a third medium setting in which one
swashplate 28 is in its minimum displacement position and one
swashplate 28 is in its maximum displacement position. Providing
three simple, discrete settings allows for greater flexibility for
speed control than hydraulic motors that have only a single
pivotable swashplate and are thus only capable of two operating
speeds.
[0016] For pivoting the swashplates 28, the motor 10 may be
equipped with an actuating system 34 that is adapted to
independently pivot the swashplates 28 between their maximum and
minimum displacement positions. In the illustrated motor 10, the
actuating assembly 34 includes one or more actuators associated
with each swashplate 28 that are operable in response to a control
signal. In this case, a pair of actuators may be provided for each
swashplate 28. In particular, a first actuator 36 acts on the
inside face of the swashplate 28 near its lower edge and a second
actuator 38 acts on the opposing outside face of the swashplate 28
near its upper edge. The actuating system 34 further includes a
spring 40 that extends between the two swashplates 28 and
operatively engages the upper edge of the inside face of each. The
spring 40 acts to push the two swashplates 28 into their maximum
displacement positions. Each of the first and second actuators 36,
38 may comprise a hydraulically actuated piston 42 and cup 44
assembly with the cups 44 disposed on the swashplates 28 and the
pistons 42 disposed on the motor housing 12.
[0017] With the illustrated arrangement, the swashplates 28 may be
pivoted into their respective minimum displacement positions by
introducing a high pressure fluid into the cups 44 of each of the
first and second actuators 36, 38. For each actuator 36, 38, the
high pressure fluid pushes the cup 44 outward relative to the
piston 42. Because the pistons 42 are fixed relative to the motor
housing 12, this generates a forces at the lower edge of the inside
face and the upper edge of the outside face of each swashplate 28
that together pivots the respective swashplate 28 against the force
of the spring 40 to the minimum displacement position. Of course,
actuators other than hydraulic actuators could be used including,
for example, electrically actuated actuators. Additionally, the
actuating system 34 could be configured such that the actuators 36,
38 pivot the swashplates 28 to the maximum displacement position
and the spring 40 biases the swashplates 28 to the minimum
displacement position. An actuating system that utilizes only a
single actuator for each swashplate could also be used. Moreover,
the actuators could comprise rotary devices configured to pivot the
swashplates.
[0018] For independently actuating the actuators 36, 38 associated
with each of the swashplates, the actuating system 34 may further
include a control signal generator 46 that is operably coupled to
the actuators 36, 38. The control signal generator 46 may be
capable of providing separate control signals to the actuators 36,
38 associated with each of the swashplates 28. Upon receipt of the
control signal, the respective actuators 36, 38 operate to pivot
the swashplate 28 to the desired position. For example, with the
illustrated motor 10, the control signal may be a supply of
pressurized fluid that is supplied to the piston 42 and cup 44
assemblies of the corresponding actuators 36, 38. The pressurized
fluid may be introduced to the motor 10 through separate first and
second actuating ports 48, 50 that are provided in the motor
housing 12. As shown in FIG. 1, in the illustrated motor, the first
actuating port 48 is in fluid communication with the first and
second actuators 36, 38 associated with the left swashplate while
the second actuating port 50 is in fluid communication with the
first and second actuators 36, 38 associated with the right
swashplate 28. Because each swashplate is changing between only two
discrete positions, the control signal generator can be relatively
simple in that it only has to provide two signal types (i.e., an
on/off type control) to each swashplate.
[0019] While the illustrated embodiment includes a single control
signal generator 46, two separate control signal generators may be
provided with each being associated with a respective one of the
swashplates 28. Of course, if another type of actuator is used,
such as electrical actuators, a corresponding control signal
generator may be used such as a control signal generator that
produces an electrical signal. Moreover, the control signal
generator could be combined with a controller for the motor or
integrated into the motor controller.
INDUSTRIAL APPLICABILITY
[0020] The present disclosure is applicable to any type of machine
that may utilize a hydraulic motor. For example, the present
disclosure may be applicable to a track loader. On such a machine,
a first hydraulic motor may be used to drive a right-side track and
a second hydraulic motor may be used to drive a left-side track. As
compared to conventional two-speed hydraulic motors, the disclosed
hydraulic motor may offer an operator of the machine with
additional flexibility with respect to speed control in that it may
operate in three different speed settings. Additionally, the use of
a floating cup arrangement may provide a higher initial starting
torque than conventional piston pumps.
[0021] It will be appreciated that the foregoing description
provides examples of the disclosed system and technique. However,
it is contemplated that other implementations of the disclosure may
differ in detail from the foregoing examples. All references to the
disclosure or examples thereof are intended to reference the
particular example being discussed at that point and are not
intended to imply any limitation as to the scope of the disclosure
more generally. All language of distinction and disparagement with
respect to certain features is intended to indicate a lack of
preference for those features, but not to exclude such from the
scope of the disclosure entirely unless otherwise indicated.
[0022] Recitation of ranges of values herein are merely intended to
serve as a shorthand method of referring individually to each
separate value falling within the range, unless otherwise indicated
herein, and each separate value is incorporated into the
specification as if it were individually recited herein. All
methods described herein can be performed in any suitable order
unless otherwise indicated herein or otherwise clearly contradicted
by context.
[0023] Accordingly, this disclosure includes all modifications and
equivalents of the subject matter recited in the claims appended
hereto as permitted by applicable law. Moreover, any combination of
the above-described elements in all possible variations thereof is
encompassed by the disclosure unless otherwise indicated herein or
otherwise clearly contradicted by context.
* * * * *