CA1166119A - Drive system for travelling a working vehicle - Google Patents
Drive system for travelling a working vehicleInfo
- Publication number
- CA1166119A CA1166119A CA000361599A CA361599A CA1166119A CA 1166119 A CA1166119 A CA 1166119A CA 000361599 A CA000361599 A CA 000361599A CA 361599 A CA361599 A CA 361599A CA 1166119 A CA1166119 A CA 1166119A
- Authority
- CA
- Canada
- Prior art keywords
- motors
- pumps
- counter balance
- valves
- travelling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Operation Control Of Excavators (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides a drive arrangement for the sys-tem of a working vehicle having two pumps for driving pressurized-fluid-driven-motors respectively mounted to the right- and left-hand travelling elements, a frame, a swivel base, a rotary joint for connecting the frame and base, a selector valve mechanism to selectively provide a condition where fluids from the pumps are respectively supplied to the right-and left-hand travelling ele-ments or a condition where fluids from the pumps are supplied in a combined flow to the travelling elements, and counter balance valves to act on the motors. The counter balance valves are dis-posed upstream with respect to the selector valve mechanism, while the counter balance valves and selector valve mechanism are locat-ed downstream of the rotary joint.
The invention provides a drive arrangement for the sys-tem of a working vehicle having two pumps for driving pressurized-fluid-driven-motors respectively mounted to the right- and left-hand travelling elements, a frame, a swivel base, a rotary joint for connecting the frame and base, a selector valve mechanism to selectively provide a condition where fluids from the pumps are respectively supplied to the right-and left-hand travelling ele-ments or a condition where fluids from the pumps are supplied in a combined flow to the travelling elements, and counter balance valves to act on the motors. The counter balance valves are dis-posed upstream with respect to the selector valve mechanism, while the counter balance valves and selector valve mechanism are locat-ed downstream of the rotary joint.
Description
The plesent invelltion relates to a drive arrangement for the travelling system of a working vehicle, in which pressur-ized--fluid-driven motors respectively mounted to the right- and left--hand travelling means of the travelling frame are adapted to be driven by two pumps mounted to the swivel base.
In a working vehicle, there has been known a travelling drive system comprising two pumps mounted to a swivel base adapted to drive pressurized-fluid-driven-motors respectively ~/e~ 7e~ f5 mounted to the right- and left-hand travelling ~ of a travelling frame, a selector valve mechanism to selectively provide a low-speed driving condition where fluids from the pumps are supplied respectively to the motors, or a high-speed driving condition where fluids from the pumps are serially supplied in the form of a combined flow to the motors, and counter balance valves to act on the motors.
In such a conventional drive arrangement, the counter balance valves have been disposed adjacent the corresponding pressurized-fluid-driven-motors respectively by usual means, and the selector valve mechanism has been disposed upstream with respect to the counter balance valves. In such an arrangement, in a condition where the selector valve mechanism is operated to provide a low-speed driving condition or a parallel connection condition where fluids from the pumps are supplied respectively to the motors, when the control valve is set to the neutral position to stop the travelling of the vehicle body, small amounts of fluids are returned to the respective counter balance valves. However, in a condition where the selector valve mechanism is operated to provide a high-speed driving condition or a series connection condition, when the control valve is set ~o the neutral position, large amounts of fluid are returned to the respective counter balance valves. Namely, when in the high-speed driving condition, the control valve is set to the neutral ~ I~A
position to stop the travelling of the vehicle body, the serially connected motors serve`as pumps by the inertia of the travelling vehicle body, thereby to gen`erate in the return lines back pres-sure higher than that genèrated in the parallel connection. This presents a problem that such a high back pressure exerts a bad in-fluence upon the piping system and the counter balance valves The present invention is proposed in view of the defect in the prior art above-mentioned and has an object to provide im-provements in a drive arrangement for the travelling system of 1~ a working vehicle, in which provision is made for counter balance valves having a small capacity to be used thereby to reduce the manufacturing cost of the drive arrangement.
Accordingly, the present invention provides a drive system for working vehicle comprising: pressurized-fluid-driven-motors adapted to be respectively mounted to right- and left-hand travelling means of a travelling frame; two pumps adapted to be mounted to a swivel base for driving said motors; a rotary joint adapted for connecting the travelling frame to the swivel base; a driving status selector valve mechanism having parallel ports and series ports to selectively provide a low-speed driving status where rlui~s from said pumps are supplied respectively in parallel to said motors or a high-speed driving status where fluids from said pumps are serially supplied in the form of a combined flow to said motors; and a counter balance valves (Va) (Vb) to act on said motors, said counter balance valves being disposed upstream with respect to said driving status selector mechanism, and said counter balance valves and said driving status selector valve mechanism both being disposed downstream of said rotary ~olnt .
In a drive arrangement for the travelling system of a w~rking vehicle of the present invention, even if the driving con-dition selector valve mechanism is operated to provide the high-'~
.
~:2~1P~
speed driving condition where the both pumps and the both motors are connected in series, fluids from the pumps combine with each other after having passed through the counter balance 1~
20.
- 2a.-valves This means fluids having only a low pressure flow in thecounter balance valves. When a travelling control valve is set to the neutral position to stop the travelling of the vehicle body, the serially connected motors are driven and serve as pumps of the series type by the inertia of the vehicle body, so that a high back pressure is generated. However, since such a high back pressure acts on the counter balance valves through branch lines in the driving condition selector valve mechanism, it means each of the counter balance valves is subjected to a small back pres-sure.
As thus discussed hereinbefore, although there is gener-ated back pressure from the motors when the vehicle body has stopped travelling, such a peculiar arrangement of the counter balance valves permits the counter balance valves to be subjected to reduced back pressure, regardless of the serial or parallel driving condition provided by the selector valve mechanism. There-fore, it becomes possible to use respective counter balance valves having a small capacity corresponding to the capacity of each motor, thus enabling to reduce the manufacturing cost of the drive arrangement. Further, the selector valve mechanism and the count-er balance valves are both mounted downstream of the rotary joint connecting the frame to the swivel base. This permits the size of the joint to be reduced.
Although the means by which the desired object is achiev-ed is simple, it is to be understood that the present invention will bring notable advantages in view of the industrial utility.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:-Fig. 1 is a general side view of a working vehicle equipped with a working vehicle drive arrangement in accordance with the present invention: and .;^~
.,, Fig. 2 i5 a pressurized 1uid circuit in an embodiment of working vehicle travelling drive system in accordance with the present invention.
In Fig. 1, a working vehicle is constituted by a tra-velling frame 2 equipped with right- and left-hand crawler tra-velling means la and lb, a swivel base 3 mounted to the travelling frame 2, a prime mover 4 and steering means 5 mounted to the swivel base 3, and an excavator 6 and a doser 7 mounted on the swivel base 3 and the travelling frame 2, respectively.
lQ As shown in Fig. 2, a drive arrangement of the travelling elements la and lb comprises: pressurized-fluid-driven-motors Ma and Mb respectively mounted to the right- and left-hand crawler traveIling elements la and lb; two pumps Pa and Pb mounted to the`swivel base 3, the pumps Pa and Pb connected to the motors Ma and Mb by lines passing through a rotary joint 8 located at the swivelling center of the swivel base 3; three-position selector valves V2 and V3 in the lines for the motors Ma and Mb to selectively provide a neutral stop, forward travel, or a rear-ward travel; a driving-condition selector valve mechanism Vl having parallel p~rts a for supplying respective fluids from the pumps Pa and Pb to the motors Ma and Mb respectively, thereby to provide a low-speed driving condition, and series ports _ for serially supplying fluids from the pumps Pa and Pb to the motors Ma and Mb in the form of a joined flow, thereby to provide a high-speed driving condition, the driving condition selector valve mechanism Vl being disposed downstream with respect to the rotary joint 8; and counter balance valves Va and Vb respectively disposed on the lines for the motors Ma and Mb between the rotary joint 8 and the driving condition selector valve mechanism Vl.
When the travelling frame 2 is stopped with the selector valves y2 and V3 set to the neutral positions, the " .
t;~
counter balance valves Va and Vb are adapted to return the fluids to the supply lines, with the back pressure generated in the return lines by the dynamic inertia of the travelling frame 2 be-ing utilized as pilot pressure, thereby to prevent the travelling frame 2 from being suddenly stopped or an undesirable action from being exerted onthè piping system.
As thus discussed hereinbefore, since the counter balance valves Va and Vb are disposed upstream with respect to the driv-ing condition selector valve mechanism Vl, it is possible to use the counter balance valves Va and Vb having a relatively small capacity. That is, if the counter balance valves Va and Vb are disposed downstream with respect to the selector valve mechanism Vl, such an arrangement requires to use the counter balance valves Va and Vb having a capacity sufficiently large to return fluids from the pumps Pa and Pb in the form of a combined flow at the time when the selector valve mechanism Vl is operated to provide the high-speed driving condition.
On the contrary, when the balance valves Va and Vb are disposed upstream with respect to the selector valve mechanism Vl, even if the selector valve mechanism Vl is operated to provide the high-speed driving condition, it is possible to branch the combined flow and cause the branched flows to act on the counter balance valves Va and Vb, whereby small-capacity counter balance valves may be advantageously used.
The valves Va-and Vb have unidirectional valves 9 to permit only the inflow of fluid to the motors Ma and Mb. In this connection, the three-position selector valves V2 and V3 have communicating lines 10 for returning fluids with back pressure generated by the motors Ma and Mb when the three-position selector 3C valves V2 and V3 are set to the neutral position.
As shown in Fig. 2 since the driving condition selector val~e mechanism Vl and the counter balance valves Va & Vb are disposed downstream from the rotary joint at the side of the tra-velling frame 2, it is not necessary to dispose at the rotary joint 8 joint flow lines having a large diameter, thereby advan-tageously to reduce the size of the rotary joint 8. Thus, the count:er balance valves Va & Vb, or the driving condition selector valve mechansim Vl and the counter balance valves Va & Vb may be disposed at the side of the swivel base 3.
It is to be understood that the drive arrangement sys-tem of a working vehicle in accordance with the present invention may be applied to a crane truck of the swivel type or the like.
In a working vehicle, there has been known a travelling drive system comprising two pumps mounted to a swivel base adapted to drive pressurized-fluid-driven-motors respectively ~/e~ 7e~ f5 mounted to the right- and left-hand travelling ~ of a travelling frame, a selector valve mechanism to selectively provide a low-speed driving condition where fluids from the pumps are supplied respectively to the motors, or a high-speed driving condition where fluids from the pumps are serially supplied in the form of a combined flow to the motors, and counter balance valves to act on the motors.
In such a conventional drive arrangement, the counter balance valves have been disposed adjacent the corresponding pressurized-fluid-driven-motors respectively by usual means, and the selector valve mechanism has been disposed upstream with respect to the counter balance valves. In such an arrangement, in a condition where the selector valve mechanism is operated to provide a low-speed driving condition or a parallel connection condition where fluids from the pumps are supplied respectively to the motors, when the control valve is set to the neutral position to stop the travelling of the vehicle body, small amounts of fluids are returned to the respective counter balance valves. However, in a condition where the selector valve mechanism is operated to provide a high-speed driving condition or a series connection condition, when the control valve is set ~o the neutral position, large amounts of fluid are returned to the respective counter balance valves. Namely, when in the high-speed driving condition, the control valve is set to the neutral ~ I~A
position to stop the travelling of the vehicle body, the serially connected motors serve`as pumps by the inertia of the travelling vehicle body, thereby to gen`erate in the return lines back pres-sure higher than that genèrated in the parallel connection. This presents a problem that such a high back pressure exerts a bad in-fluence upon the piping system and the counter balance valves The present invention is proposed in view of the defect in the prior art above-mentioned and has an object to provide im-provements in a drive arrangement for the travelling system of 1~ a working vehicle, in which provision is made for counter balance valves having a small capacity to be used thereby to reduce the manufacturing cost of the drive arrangement.
Accordingly, the present invention provides a drive system for working vehicle comprising: pressurized-fluid-driven-motors adapted to be respectively mounted to right- and left-hand travelling means of a travelling frame; two pumps adapted to be mounted to a swivel base for driving said motors; a rotary joint adapted for connecting the travelling frame to the swivel base; a driving status selector valve mechanism having parallel ports and series ports to selectively provide a low-speed driving status where rlui~s from said pumps are supplied respectively in parallel to said motors or a high-speed driving status where fluids from said pumps are serially supplied in the form of a combined flow to said motors; and a counter balance valves (Va) (Vb) to act on said motors, said counter balance valves being disposed upstream with respect to said driving status selector mechanism, and said counter balance valves and said driving status selector valve mechanism both being disposed downstream of said rotary ~olnt .
In a drive arrangement for the travelling system of a w~rking vehicle of the present invention, even if the driving con-dition selector valve mechanism is operated to provide the high-'~
.
~:2~1P~
speed driving condition where the both pumps and the both motors are connected in series, fluids from the pumps combine with each other after having passed through the counter balance 1~
20.
- 2a.-valves This means fluids having only a low pressure flow in thecounter balance valves. When a travelling control valve is set to the neutral position to stop the travelling of the vehicle body, the serially connected motors are driven and serve as pumps of the series type by the inertia of the vehicle body, so that a high back pressure is generated. However, since such a high back pressure acts on the counter balance valves through branch lines in the driving condition selector valve mechanism, it means each of the counter balance valves is subjected to a small back pres-sure.
As thus discussed hereinbefore, although there is gener-ated back pressure from the motors when the vehicle body has stopped travelling, such a peculiar arrangement of the counter balance valves permits the counter balance valves to be subjected to reduced back pressure, regardless of the serial or parallel driving condition provided by the selector valve mechanism. There-fore, it becomes possible to use respective counter balance valves having a small capacity corresponding to the capacity of each motor, thus enabling to reduce the manufacturing cost of the drive arrangement. Further, the selector valve mechanism and the count-er balance valves are both mounted downstream of the rotary joint connecting the frame to the swivel base. This permits the size of the joint to be reduced.
Although the means by which the desired object is achiev-ed is simple, it is to be understood that the present invention will bring notable advantages in view of the industrial utility.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:-Fig. 1 is a general side view of a working vehicle equipped with a working vehicle drive arrangement in accordance with the present invention: and .;^~
.,, Fig. 2 i5 a pressurized 1uid circuit in an embodiment of working vehicle travelling drive system in accordance with the present invention.
In Fig. 1, a working vehicle is constituted by a tra-velling frame 2 equipped with right- and left-hand crawler tra-velling means la and lb, a swivel base 3 mounted to the travelling frame 2, a prime mover 4 and steering means 5 mounted to the swivel base 3, and an excavator 6 and a doser 7 mounted on the swivel base 3 and the travelling frame 2, respectively.
lQ As shown in Fig. 2, a drive arrangement of the travelling elements la and lb comprises: pressurized-fluid-driven-motors Ma and Mb respectively mounted to the right- and left-hand crawler traveIling elements la and lb; two pumps Pa and Pb mounted to the`swivel base 3, the pumps Pa and Pb connected to the motors Ma and Mb by lines passing through a rotary joint 8 located at the swivelling center of the swivel base 3; three-position selector valves V2 and V3 in the lines for the motors Ma and Mb to selectively provide a neutral stop, forward travel, or a rear-ward travel; a driving-condition selector valve mechanism Vl having parallel p~rts a for supplying respective fluids from the pumps Pa and Pb to the motors Ma and Mb respectively, thereby to provide a low-speed driving condition, and series ports _ for serially supplying fluids from the pumps Pa and Pb to the motors Ma and Mb in the form of a joined flow, thereby to provide a high-speed driving condition, the driving condition selector valve mechanism Vl being disposed downstream with respect to the rotary joint 8; and counter balance valves Va and Vb respectively disposed on the lines for the motors Ma and Mb between the rotary joint 8 and the driving condition selector valve mechanism Vl.
When the travelling frame 2 is stopped with the selector valves y2 and V3 set to the neutral positions, the " .
t;~
counter balance valves Va and Vb are adapted to return the fluids to the supply lines, with the back pressure generated in the return lines by the dynamic inertia of the travelling frame 2 be-ing utilized as pilot pressure, thereby to prevent the travelling frame 2 from being suddenly stopped or an undesirable action from being exerted onthè piping system.
As thus discussed hereinbefore, since the counter balance valves Va and Vb are disposed upstream with respect to the driv-ing condition selector valve mechanism Vl, it is possible to use the counter balance valves Va and Vb having a relatively small capacity. That is, if the counter balance valves Va and Vb are disposed downstream with respect to the selector valve mechanism Vl, such an arrangement requires to use the counter balance valves Va and Vb having a capacity sufficiently large to return fluids from the pumps Pa and Pb in the form of a combined flow at the time when the selector valve mechanism Vl is operated to provide the high-speed driving condition.
On the contrary, when the balance valves Va and Vb are disposed upstream with respect to the selector valve mechanism Vl, even if the selector valve mechanism Vl is operated to provide the high-speed driving condition, it is possible to branch the combined flow and cause the branched flows to act on the counter balance valves Va and Vb, whereby small-capacity counter balance valves may be advantageously used.
The valves Va-and Vb have unidirectional valves 9 to permit only the inflow of fluid to the motors Ma and Mb. In this connection, the three-position selector valves V2 and V3 have communicating lines 10 for returning fluids with back pressure generated by the motors Ma and Mb when the three-position selector 3C valves V2 and V3 are set to the neutral position.
As shown in Fig. 2 since the driving condition selector val~e mechanism Vl and the counter balance valves Va & Vb are disposed downstream from the rotary joint at the side of the tra-velling frame 2, it is not necessary to dispose at the rotary joint 8 joint flow lines having a large diameter, thereby advan-tageously to reduce the size of the rotary joint 8. Thus, the count:er balance valves Va & Vb, or the driving condition selector valve mechansim Vl and the counter balance valves Va & Vb may be disposed at the side of the swivel base 3.
It is to be understood that the drive arrangement sys-tem of a working vehicle in accordance with the present invention may be applied to a crane truck of the swivel type or the like.
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A drive system for working vehicle comprising:
pressurized-fluid-driven-motors adapted to be respectively mounted to right- and left-hand travelling means of a travelling frame;
two pumps adapted to be mounted to a swivel base for driving said motors; a rotary joint adapted for connecting the travelling frame to the swivel base; a driving status selector valve mechanism having parallel ports and series ports to selectively provide a low-speed driving status where fluids from said pumps are supplied respectively in parallel to said motors or a high-speed driving status where fluids from said pumps are serially supplied in the form of a combined flow to said motors; and counter balance valves (Va) (Vb) to act on said motors, said counter balance valves being disposed upstream with respect to said driving status selector mechanism, and said counter balance valves and said driving status selector valve mechanism both being disposed downstream of said rotary joint.
pressurized-fluid-driven-motors adapted to be respectively mounted to right- and left-hand travelling means of a travelling frame;
two pumps adapted to be mounted to a swivel base for driving said motors; a rotary joint adapted for connecting the travelling frame to the swivel base; a driving status selector valve mechanism having parallel ports and series ports to selectively provide a low-speed driving status where fluids from said pumps are supplied respectively in parallel to said motors or a high-speed driving status where fluids from said pumps are serially supplied in the form of a combined flow to said motors; and counter balance valves (Va) (Vb) to act on said motors, said counter balance valves being disposed upstream with respect to said driving status selector mechanism, and said counter balance valves and said driving status selector valve mechanism both being disposed downstream of said rotary joint.
2. A drive system as set forth in claim 1, further comprising three-position selector valves to selectively provide each of said motors with a neutral stop position, a forward travel position or a rearward travel position, said three-position selector valves being disposed between said pumps and said counter balance valves.
3. A drive system as in claim 2, wherein said three-position selector valves include lines for returning fluids with back pressure generated by said motors when said three-position selector valves are in said neutral stop position.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000361599A CA1166119A (en) | 1980-10-06 | 1980-10-06 | Drive system for travelling a working vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000361599A CA1166119A (en) | 1980-10-06 | 1980-10-06 | Drive system for travelling a working vehicle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1166119A true CA1166119A (en) | 1984-04-24 |
Family
ID=4118070
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000361599A Expired CA1166119A (en) | 1980-10-06 | 1980-10-06 | Drive system for travelling a working vehicle |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1166119A (en) |
-
1980
- 1980-10-06 CA CA000361599A patent/CA1166119A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |