Information
-
Patent Grant
-
6354184
-
Patent Number
6,354,184
-
Date Filed
Tuesday, September 14, 199925 years ago
-
Date Issued
Tuesday, March 12, 200222 years ago
-
CPC
-
US Classifications
Field of Search
US
- 091 418
- 091 459
- 137 62565
- 251 12911
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International Classifications
-
Abstract
A power machine or a skid steer loader that is driven by an engine and has hydraulic pump, hydraulic fluid conduit, a hydraulic motor in fluid communication with a hydraulic fluid conduit and a valve that is operated or actuated by linear actuator such that the linear actuator is mounted directly on the valve block.
Description
BACKGROUND OF THE INVENTION
The present invention generally relates to valve mountings for hydraulic systems in power machines. In particular, the present invention relates to the direct mounting of valve actuators on valve blocks.
Machines such as skid steer loaders and other power machines employing conventional hydraulic systems need valves for their operation. These valves utilize linear actuation mechanisms. Currently, linear actuators are not directly mounted on the valve surface, but instead, they are mounted on a separate portion of the system such as a support plate. The sliding plunger of the actuator is connected to the spool of the valve. Since the linear actuator is positioned separate from the valve, the sliding plunger and the portion of the valve spool extending from the valve block have to be covered by a sealed rubber boot in order to prevent penetration by any dust from the exterior.
The separation of the actuator and the valve poses several problems in conventional systems. Some of the problems include:
1. The rubber boot provides limited protection from dirt, but over a period of time dirt penetrates into the area surrounding the plunger and the exterior of the spool.
2. The plunger may not be aligned with the spool, thereby resulting in reduced efficiency as a result of all the force not acting in a linear direction.
3. The valve and the actuator have separate tolerances due to being spaced apart.
4. The center line of the plunger is offset from the center line of the spool resulting in a possibility of an induced moment.
5. Mounting of the actuator on the support plate prevents rotation of the motor about the axis of the plunger and thereby does not provide for good clearance of other parts.
SUMMARY OF THE INVENTION
The valve assembly of the present invention utilizes a linear actuator that is mounted directly on the valve block around an exterior projection of the valve spool. The direct mounting of the actuator on the valve block provides a substantially air tight mounting for the valve assembly.
Direct mounting of the actuator on the valve block can be efficiently utilized in machines such as skid steer loaders and other power machines that employ hydraulic circuits for their operation.
An illustrative embodiment of the valve assembly has an actuator which has a sleeve with an internal plunger that can be moved within the sleeve. One end of the sleeve has an actuator motor that drives the plunger and the other end of the sleeve has a flange. The sleeve also has a collar with a pair of bores through which screws can be passed to bolt the sleeve rigidly to the valve mount. A retainer seal with a cylindrical groove and a pair of bolt holes provides an interface between the actuator sleeve and the valve block. The retainer seal also has a grooved portion called the O-ring groove which is dimensioned to receive the flange on the sleeve such that an air tight coupling is made between the sleeve and the retainer seal.
Therefore, one embodiment of the invention provides a direct and rigid coupling between the linear actuator and the valve block.
An embodiment of the invention also provides a direct coupling between the linear actuator and the valve surface which is sufficiently tight so that dirt is prevented from penetrating into the valve bore.
An embodiment of the invention further provides and maintains a linear connection between the plunger and the spool at all times.
A further aspect of the invention prevents the pin connection between the plunger and the spool from slipping by always maintaining the pin within a cylindrical portion.
These embodiments and aspects of the invention are not meant to be exclusive and other features, aspects, and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description, appended claims and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a perspective view illustrating the side and rear of a skid steer loader that utilizes the valve assembly of the present invention.
FIG. 2
is a perspective view illustrating the front and side of a skid steer loader.
FIG. 3
is a functional diagram of a typical hydraulic system that can utilize valve assemblies of the present invention.
FIG. 4
is a block diagram of a hydraulic system which can utilize valve assemblies of the present invention.
FIG. 5
is a perspective view illustrating pertinent individual parts that form one embodiment of the valve assembly of the present invention.
FIG. 6A
is a top view of the motor connection end of the linear actuator for one embodiment of the valve assembly.
FIG. 6B
shows details of the end of the linear actuator that is connected to the valve mount.
FIGS. 6C and 6D
also show details of the end of the linear actuator that is connected to the valve mount.
FIG. 7A
is a top view of the retainer seal looking down at the end of the retainer seal that fits into the valve surface.
FIG. 7B
shows details of the retainer seal.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
The following detailed description should be read with reference to the drawings in which like elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention.
FIGS. 1 and 2
illustrate perspective views of a skid steer loader
10
which can be used with the present invention. Skid steer loader
10
includes a mainframe assembly
16
, a lift arm assembly
30
, and an operator's compartment
40
. An engine compartment
22
and a heat exchanger compartment
24
are illustratively located at the rear of the skid steer loader
10
. Two pairs of wheels
12
are mounted to stub axles
14
and extend from both sides of the mainframe
16
.
Lift arm assembly
30
is mounted to upright members
20
of the mainframe assembly
16
. Lift arm assembly
30
includes an upper portion formed by a pair of lift arms
32
which extend over wheels
12
and are pivotally mounted at a rear end to upright members
20
. The front end of lift arms
32
are connected to a lower potion
33
which is pivotally attached to a tool (such as a bucket)
34
. Lift arm assembly
30
is raised and lowered with respect to the mainframe assembly
16
by a pair of lift cylinders
36
. Each of the lift cylinders
36
includes a first end pivotally mounted to upright member
20
and a second end pivotally mounted to lift arm
32
. Bucket
34
is pivoted with respect to lift arm
32
by means of a bucket tilt cylinder (not shown).
Operator compartment
40
is partially enclosed by a cab
42
which includes side guard panels
44
, overhead panel
46
, rear guard panel
48
, back panel
50
and seat pan
52
. Cab
42
illustratively and optionally acts as an integral unit which is pivotally mounted at its rear to mainframe
16
. With this arrangement, the entire cab, including seat
54
, may be pivoted upwardly and toward the rear of the loader
10
in order to permit access to the engine compartment
22
in addition to other mechanical and hydraulic systems of the skid steer loader
10
.
All functions of the skid steer loader
10
may be controlled by an operator who illustratively sits in the operator's compartment
40
. The hydraulic drive system, which is described in more detail hereinafter, may be controlled using a pair of steering levers
58
, one on each side of the seat. Each of the levers
58
may be moved independently in a forward and rearward direction. Movement of the levers
58
cause the wheels
12
on the corresponding side of the loader to rotate at a speed and in a direction corresponding to the extent and direction in which the respective lever
58
is moved. For example, if the left hand lever is moved in the forward direction, the left hand wheels
12
rotate in the forward direction at a speed corresponding to the distance the lever
58
has been moved. The left cylinder
36
and the bucket tilt cylinder (not shown) are actuated by means of foot pedals (not shown) or operator inputs on handles or hand grips on steering levers
58
or on a dash mounted toward the front of the operator's compartment
40
. These and other aspects of the operation of the skid steer loader
10
are known to those skilled in the art.
FIG. 3
illustrates a functional diagram of a conventional hydrostatic drive system
60
. Hydrostatic drive system
60
includes left and right hydraulic drive pumps (illustrated by block
76
,
78
in
FIG. 3
) driven by engine
21
and controlled by operator inputs
58
. Hydraulic drive pumps
76
,
78
are coupled to left and right hydraulic motors (illustrated by numerals
64
,
66
in
FIG. 3
) by way of hydraulic loops (illustrated by numerals
84
,
86
in
FIG. 3
) which pass through flushing valve
150
. The hydraulic motors
64
,
66
are coupled to a wheel
12
by way of a drive train
13
. Wheel
12
and drive train
13
are shown collectively as
12
,
13
in FIG.
3
. Operator input mechanisms
58
are individually coupled by linkages (not shown) to valves associated with left motor pump
76
and right motor pump
78
. The direction and extent to which the operator input mechanisms
58
are moved directly affects the direction and volume of hydraulic fluid provided to drive motors
64
and
66
and therefore the direction and speed at which the loader
10
is driven. A relatively high pressure is typically encountered when the hydraulic motors
64
,
66
are driven at relatively high speed. When the pressure in the hydraulic loops
84
,
86
reaches a threshold high pressure, the flushing valve
150
exhausts oil to reservoir
62
.
The hydraulic system of
FIG. 3
also includes a hydraulic circuit
90
that has an auxiliary pump that is coupled to the lift cylinder
36
(shown in FIGS.
1
and
2
), tilt cylinder and auxiliary ports. A valve block
92
for hydraulic circuit
90
includes a tilt valve
94
, lift valve
96
and auxiliary valve
98
interconnected in the hydraulic circuit. Valve block
92
can either be integrally formed or formed by discretely mounted valves. Valves
94
,
96
and
98
can be implemented using electrically actuated spool valves or manually actuated spool valves coupled by linkages, which may be mechanical or electrical linkages to an operator input device such as a foot pedal located in the front of the operator compartment
40
or a hand control illustratively located on a handgrip on one of the levers,
58
.
FIG. 4
is a block diagram of a hydraulic system similar to that of
FIG. 3
, and in addition, showing a valve actuator
138
for valve
134
(which is illustratively one of the valves mounted in valve block
92
). Fluid is provided under pressure by pump
132
to valve
134
. Movement of the hydraulic actuator
136
(which can be a linear motor such as a cylinder or rotary hydraulic motor or any other desired motor) can be controlled by adjusting the state of valve
134
to either block or conduct pressurized fluid. Valve adjustment is controlled by user or electrical input
140
to a valve actuator
138
, which in turn causes movement of a valve spool that controls the passage of fluid through the valve
134
.
FIG. 5
illustrates a basic layout of an illustrative embodiment of the present invention. Valve
210
(which can correspond to valve
134
in
FIG. 4
) includes a housing
211
which defines a bore, a fluid inlet and a fluid outlet. Valve
210
also has spool
224
slidably received within the bore with a portion of the spool
224
projecting outside the surface of the valve housing
211
.
Actuator
212
(which can correspond to actuator
138
in
FIG. 4
) is directly coupled to the projection of spool
224
. Actuator
212
has a motor
214
that drives a plunger
222
which is housed within a sleeve
216
. The plunger
222
is connected to motor
214
at one end and to spool
224
of the valve
210
at the other end. Operation of valve
210
will now be described with the help of
FIGS. 4 and 5
.
User or electrical input to operate the hydraulic actuator
136
(shown in
FIG. 4
) is translated to a signal whose magnitude and direction corresponds to a selection made by the user or operator. This signal is applied to motor
214
of actuator
212
. Based on this signal, motor
214
drives plunger
222
within sleeve
216
forward or backward along a longitudinal axis. Since plunger
222
is directly coupled to spool
224
, and both plunger
222
and spool
224
are along the same longitudinal axis, movement of the plunger
222
results in a corresponding extension or withdrawal of spool
224
within the base (not shown) of valve housing
211
. Movement of the spool
224
within the bore causes partial or complete opening/closing of the fluid inlet and outlet in valve
210
. Control of the opening or closing of the fluid inlet and outlet of the valve
210
controls the flow rate and volume of pressurized fluid that is communicated to the hydraulic actuator
136
from pump
132
, thereby providing for effective operation of the hydraulic actuator
136
.
Sleeve
216
(shown in
FIG. 5
) has a collar
218
slidably disposed on its outer surface. Collar
218
is used to clamp the actuator
212
to the valve block or housing
211
.
FIG. 5
also shows retainer seal
220
which forms an interface between the actuator
212
and the valve block or housing
211
. In an assembled condition, the actuator
212
and retainer seal
220
form a direct and fluid tight or air tight coupling for the valve
210
and actuator
212
.
FIGS. 6A-6D
show details of the end of the actuator
212
that is connected to the spool
224
of valve
210
.
FIGS. 7A and 7B
show details of the retainer seal
220
. These figures will now be described in conjunction with one another.
The portion of the plunger
222
that is connected to the spool
224
has a recess
222
A which is sized to receive the end of the spool
224
. The recess portion
222
A of the plunger
222
has identically sized opposing hollow cylindrical grooves
222
B
1
and
222
B
2
. A cylindrical groove
224
A of diameter substantially equal to the diameters of grooves
222
B
1
and
222
B
2
passes through extended position of spool
224
that fits into recess
222
A. When groove
224
A is positioned within recess
222
A and aligned with grooves
222
B
1
and
222
B
2
, a pin can be passed through these grooves to hold plunger
222
and spool
224
together. The pin is always held in position because it is always situated within a cylinder when the apparatus is assembled.
The sleeve
216
has a flange
216
A radially sized to fit into an O-ring groove
220
A on the retainer seal
220
. By fitting the flange
216
A into the O-ring groove
220
A, which also has an O-ring
221
disposed therein, effective protection from dirt at the junction of the plunger and the spool is provided.
The collar
218
has bores
218
A and
218
B and retainer seal
220
also has bores
220
D and
220
E of a substantially similar size as collar bores
218
A and
218
B such that screws can be passed through their bores to connect the actuator
212
to the valve housing
211
via the retainer seal
220
. The collar
218
also has a recess
218
C (shown in
FIG. 6D
) that is dimensioned to fit around flange
216
A when the collar
218
and retainer seal
220
are bolted to the valve block or housing
211
. The retainer seal
220
also has a projection
220
C that fits into valve block or housing
211
to provide additional stability for the valve assembly.
Direct assembly of the actuator
212
on the valve block or housing
211
can be easily accomplished by first passing the retainer seal
220
over the projecting end of the spool
224
and then inserting the end of actuator
212
that has flange
216
A and plunger recess
222
A into the retainer seal
220
. The extending end of spool
224
is then positioned in recess
222
A to align recess grooves
222
B
1
and
222
B
2
and spool groove
224
A. A pin is snapped into these grooves to hold the spool
224
and plunger
222
together. Flange
216
A is then fitted into O-ring groove
220
A that has an O-ring
221
therein. Collar
218
is then closely positioned against retainer seal
220
with portion of the flange
216
A that is outside the O-ring groove
220
A fitting into collar recess
218
C. Collar bores
218
A and
218
B are aligned with retainer seal bores
220
D and
220
E. Screws are then passed into these bores and tightened into valve block or housing
211
. This completes a structurally simple and easily mountable valve assembly.
It should also be noted that retainer (or spacer)
220
can be formed in a wide variety of different ways. For example, the machined O-ring groove
220
A can be eliminated so the parts simply contact one another in a face-to-face (or other) manner. Similarly, projection
220
C can be eliminated, or provided on valve block or housing
211
rather than on retainer
220
. Other changes can be made to retainer
220
, or other parts, as well.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
Claims
- 1. A valve assembly for a hydraulic valve actuator used in a skid steer loader, the valve assembly comprising:a valve that includes a valve housing having a bore, a fluid inlet and a fluid outlet; a spool slidably received within the bore, the spool having an outer end; a linear actuator that includes a hollow cylindrical sleeve, a plunger slidably arranged within the hollow cylindrical sleeve and connectable to the outer end of the spool, and a motor operably coupled to the plunger; a collar disposed on the hollow cylindrical sleeve; a retainer seal having an actuator end that is spaced apart from a valve end, and also having a groove extending through the retainer seal from the actuator end to the valve end, such that the retainer seal forms an interface between the linear actuator and the valve that is sufficient to space the linear actuator from the valve while inhibiting dirt penetration into an interior thereof; and a bolt path defined by the collar, the retainer seal, and the valve, the bolt path being configured to receive a bolt that secures the linear actuator, the retainer seal and the valve firmly together.
- 2. The valve assembly of claim 1, wherein the motor is positioned at a first end of the hollow cylindrical sleeve.
- 3. The valve assembly of claim 2, wherein the plunger is connected to the outer end of the spool at a second end of the hollow cylindrical sleeve.
- 4. The valve assembly of claim 1, wherein the plunger defines a recess that receives the outer end of the spool.
- 5. The valve assembly of claim 4, wherein the spool is connected to the plunger within the recess with a pin.
- 6. The valve assembly of claim 1, wherein the collar is slidably positioned on the hollow cylindrical sleeve to facilitate clamping of the linear actuator to the actuator end of the retainer seal.
- 7. The valve assembly of claim 6, wherein the collar defines a plurality of collar bores that are a portion of the bolt path and are configured to receive bolts.
- 8. The valve assembly of claim 7, wherein the retainer seal defines a plurality of retainer seal bores aligned with the plurality of collar bores on the collar, the plurality of retainer seal bores being a portion of the bolt path and being configured to receive bolts.
- 9. The valve assembly of claim 8, wherein the collar, the retainer seal and the valve housing are connected via a plurality of bolts that pass through the collar bores and the retainer seal bores into bores formed in the valve housing.
- 10. The valve assembly of claim 6, wherein the sleeve further comprises a flange positioned between the collar and the retainer seal.
- 11. The valve assembly of claim 10, wherein the retainer seal has an O-ring groove and an O-ring deposited therein, such that the flange abuts the O-ring to form a substantially fluid tight connection inhibiting dirt from penetrating into the junction of the plunger and the spool.
- 12. A skid steer loader comprising:an engine; a hydraulic drive pump coupled to and driven by the engine; a hydraulic fluid conduit in fluid communication with the hydraulic drive pump; a hydraulic motor in fluid communication with the hydraulic fluid conduit; a valve that is in fluid communication with the hydraulic fluid conduit; and a linear actuator operably disposed relative to the valve and having a flange positioned on one end of a cylindrical sleeve; and a retainer seal forming a connection interface between the linear actuator and the valve, the retainer seal having a valve end that is spaced apart from an actuator end that is configured to receive the flange, the entire retainer seal being configured to enable a connection that spaces the linear actuator from the valve while at the same time forming an effective fluid tight interface there between.
- 13. The skid steer loader of claim 12, wherein the retainer seal has an O-ring groove and an O-ring disposed therein, such that the flange abuts the O-ring to form a substantially fluid tight connection between the linear actuator and the valve housing.
- 14. A power machine comprising:an engine; a hydraulic drive pump coupled to and driven by the engine; a hydraulic fluid conduit in fluid communication with the hydraulic drive pump; a hydraulic motor in fluid communication with the hydraulic fluid conduit; a valve that is in fluid communication with the hydraulic fluid conduit; a linear actuator operably disposed relative to the valve; a collar disposed on the linear actuator; a retainer seal forming a connection interface between the linear actuator and the valve, the retainer seal having a valve end that is spaced apart from an actuator end, the retainer seal being configured to enable a connection that spaces the linear actuator from the valve while at the same time forming an effective fluid tight interface there between; and a bolt path defined by the collar, the retainer seal, and the valve, the bolt path being configured to receive a bolt that secures the linear actuator, the retainer seal and the valve firmly together.
- 15. The power machine of claim 14, further comprising:a sleeve for the linear actuator, the sleeve having a retainer seal end; a flange positioned at the retainer seal end of the sleeve; and an O-ring groove in the retainer seal, and an O-ring disposed therein, such that the flange abuts the O-ring to form a substantially fluid tight connection between the linear actuator and the valve housing.
- 16. The power machine of claim 15, wherein the hydraulic motor is selected from a group consisting of a rotary motor, a linear motor, a lift cylinder, a tilt cylinder and an auxiliary coupler.
US Referenced Citations (9)
Foreign Referenced Citations (3)
Number |
Date |
Country |
1458177 |
Dec 1965 |
FR |
1093494 |
Jul 1964 |
GB |
WO 9318327 |
Sep 1993 |
WO |