Interrelated power delivery controls – including engine control – Transmission control – Engine starting interlock
Reexamination Certificate
1999-11-10
2001-04-10
Marmor, Charles A. (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Engine starting interlock
C477S125000, C091S459000
Reexamination Certificate
active
06213912
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates generally to hydraulic controls for a variable output hydraulic device such as a transmission or hydraulic flow system on a vehicle, and more specifically, to a simple circuit for inhibiting initial high speed or high volume operation of such a system upon start up of the vehicle.
2) Related Art
Utility vehicles such as skid steer loaders often include a hydraulically driven transmission having low speed and high speed operation. Valves on the transmission are electronically controlled to select speed, and a switch or other transmission speed select control at the operator console connected to the valve solenoid of one of the valves allows the operator to choose either the low speed or high speed range. In many systems, if the operator shuts down the vehicle with the select control in a high speed position, the high speed operation selection will carry over after the next start up unless the operator manually moves the select control.
It is often desirable to have vehicle operation after start up commence in the low speed range rather than the high speed range. Assuring that the low speed range is selected regardless of the position of the selection control can require complicated mechanical or electrical interlocks or interlock circuitry. Arrangements that only allow vehicle starting only if the low speed is manually selected can be complex and expensive and can be confusing to the operator.
Other hydraulic systems on the vehicle may have electrohydraulic valves or similar control devices for providing a variable hydraulic output. In many applications it is desirable to inhibit high flow or volume output upon vehicle start up.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved system for returning a transmission to a low speed range after vehicle shut down. It is a further object to provide such an improved system which has a manual operator control and which obviates need for the operator to move the control to the low speed range at start up.
It is a further object of the present invention to provide an improved system for returning a transmission to the low speed range which is very simple and inexpensive in construction and which has an easy to understand operation. It is a further object to provide such a system which has a simple manually operated control and which assures initial vehicle operation in the low speed range unless the operator moves the control after start up of the vehicle.
It is still another object of the present invention to provide an improved system for a hydraulic system having an electronically operated valve or other fluid control device with a manually controlled switch for varying device output between a low volume operation and a higher volume operation, wherein after shut down of the system, the low volume operation will be initially provided upon start up regardless of the switch position on powering up. It is a further object to provide such a system wherein the switch must be operated after powering up to select the high volume operation.
A vehicle speed control system constructed in accordance with the teachings of the present invention includes a high speed/low speed selection switch and a speed control relay connected to a voltage source through a switched power line. The speed selection switch includes an input connected to the power line via the speed control relay. One output on the speed control switch is connected to an electrohydraulic valve which controls the speed range on a vehicle. The state of the electrohydraulic valve is dependent both on the switch position and on the state of the relay. The relay is deactivated when the power line is switched off and changes back to an activated state to allow high speed operation only if the speed selection switch is in or is placed in the low speed position after the vehicle power line is switched on. If the selection switch is in the high speed position when the power line is on, the speed control relay will remain inactivated until the selection switch is moved to the low speed position. Thereafter, movement of the selection switch to the high speed position with the switched power line on and the speed control relay activated activates the electrohydraulic valve to place the vehicle in the high speed condition.
A system with a control switch and relay similar to that of the speed control system may also be utilized with a variable flow hydraulic system which provides additional hydraulic flow to auxiliary equipment powered by the vehicle. A control switch includes off, run and on positions and is connected to flow control relay and to a switched power line. In the off position of the switch, or when the power line is off, the relay deactivates to provide low hydraulic flow. Thereafter, to bootstrap the relay to the on position and select the high hydraulic flow, the switch must first be moved to the on position before being released to the run position.
The control system is relatively simple and inexpensive and prevents high speed vehicle operation or high volume hydraulic fluid flow until the operator manually changes the selection switch, even if the switch is in the high speed or high volume position when the vehicle is powered up. Complicated and expensive interlock linkages or circuits are eliminated, and system operation is easy and straightforward.
These and other objects, features and advantages of the present invention will become apparent to one skilled in the art upon reading the following detailed description in view of the drawings.
REFERENCES:
patent: 3574288 (1971-04-01), Barth
patent: 3748929 (1973-07-01), Green
patent: 4542721 (1985-09-01), Williams
patent: 4981052 (1991-01-01), Gierer
patent: 5078104 (1992-01-01), Peterson, Jr.
patent: 5314038 (1994-05-01), Peterson, Jr.
patent: 5513551 (1996-05-01), Morishita
patent: 5778330 (1998-07-01), McKee
patent: 5809441 (1998-09-01), McKee
patent: 6145312 (2000-11-01), Hauser et al.
Deere & Company
Marmor Charles A.
Pang Roger
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