Control system for an automatic vehicle transmission
First Claim
1. In an automatic transmission for a motor vehicle, having an accelerator pedal and a brake pedal, said transmission having hydraulically actuatable gear shift elements, a gear select lever having a plurality of selectable forward drive positions, including automatic forward drive (D), a source of first pressurized hydraulic fluid, and a manual control valve, responsive to the position of said select lever, for supplying said first fluid to a selected gear shift element when said lever is in one of said forward drive positions, a control system for selectively interrupting the supply of said first fluid to said selected element comprising a main control valve for controlling the supply of said first fluid from said manual control valve to said selected element, means for providing a second fluid pressure for acting on said main control valve for connecting the supply of said first fluid to said element for engaging said element, and a purging control valve means responsive to the position of said accelerator pedal for venting the second fluid pressure supplied to said main control valve when the accelerator pedal is released, to discontinue said first fluid supply and exhaust the fluid from said element to disengage said element, the improvement comprising means responsive to the position of said brake pedal for controlling said main control valve for permitting said element to disengage only when said brake pedal is depressed.
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Accused Products
Abstract
An automatic transmission for a motor vehicle of the type having a mechanical planetary gear train with hydraulically actuatable gear shift elements has a gear select lever having a plurality of selectable forward drive positions, including automatic forward drive (D). A manual control valve, responsive to the position of the select lever, supplies a first pressurized hydraulic fluid to a selected gear shift element, e.g. a forward gear clutch, when the lever is in one of said forward drive positions. A control system which selectively interrupts the supply of fluid to the selected element comprises a main control valve, and a second fluid pressure acting on the main control valve to connect the supply of the first fluid to the gear shift element for engaging the element. A purging control valve vents the second fluid pressure supplied to the main control valve when the accelerator pedal is released, to discontinue the first fluid supply and exhaust the fluid from the gear shift element to disengage the element. A brake pedal position dependent control acts on the main control valve for permitting the gear shift element to disengage only when the brake pedal is depressed.
16 Citations
9 Claims
- 1. In an automatic transmission for a motor vehicle, having an accelerator pedal and a brake pedal, said transmission having hydraulically actuatable gear shift elements, a gear select lever having a plurality of selectable forward drive positions, including automatic forward drive (D), a source of first pressurized hydraulic fluid, and a manual control valve, responsive to the position of said select lever, for supplying said first fluid to a selected gear shift element when said lever is in one of said forward drive positions, a control system for selectively interrupting the supply of said first fluid to said selected element comprising a main control valve for controlling the supply of said first fluid from said manual control valve to said selected element, means for providing a second fluid pressure for acting on said main control valve for connecting the supply of said first fluid to said element for engaging said element, and a purging control valve means responsive to the position of said accelerator pedal for venting the second fluid pressure supplied to said main control valve when the accelerator pedal is released, to discontinue said first fluid supply and exhaust the fluid from said element to disengage said element, the improvement comprising means responsive to the position of said brake pedal for controlling said main control valve for permitting said element to disengage only when said brake pedal is depressed.
Specification