Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
278 words
A hydraulic control device for an automatic automotive transmission system in which a speed stage is selected from a plurality of speed stages by removing pressure from a first hydraulic engagement element provided in a path of power transmission and supplying pressure to a second hydraulic engagement element provided in another path of power transmission, comprising: an oil ejection passage connected to a port of an oil chamber of said first hydraulic engagement element; an oil ejection control valve having an inlet port connected to said oil ejection passage, an outlet port connected to an oil reservoir, a valve member, spring means urging said valve member to a position to substantially close a communication between said inlet port and said outlet port, a first pressure input port for applying pressure to a first pressure receiving surface of said valve member to move said valve member in a direction to open a communication between said inlet port and said outlet port against a biasing force of said spring means, and a second pressure input port for applying pressure to a second pressure receiving surface of said valve member to move said valve member in a direction to open a communication between said inlet port and said outlet port against a biasing force of said spring means; an ejection pressure oil passage connected between a port of an oil chamber of said first hydraulic engagement element and said first pressure input port of said oil ejection control valve; and a supply pressure oil passage connected between a port of an oil chamber of said second hydraulic engagement element and said second pressure input port of said oil ejection control valve.
Claim 2
Dependent Claim
278 words
A hydraulic control device for an automatic automotive transmission system in which a speed stage is selected from a plurality of speed stages by removing pressure from a first hydraulic engagement element provided in a path of power transmission and supplying pressure to a second hydraulic engagement element provided in another path of power transmission, comprising: an oil ejection passage connected to a port of an oil chamber of said first hydraulic engagement element; an oil ejection control valve having an inlet port connected to said oil ejection passage, an outlet port connected to an oil reservoir, a valve member, spring means urging said valve member to a position to substantially close a communication between said inlet port and said outlet port, a first pressure input port for applying pressure to a first pressure receiving surface of said valve member to move said valve member in a direction to open a communication between said inlet port and said outlet port against a biasing force of said spring means, and a second pressure input port for applying pressure to a second pressure receiving surface of said valve member to move said valve member in a direction to open a communication between said inlet port and said outlet port against a biasing force of said spring means; an ejection pressure oil passage connected between a port of an oil chamber of said first hydraulic engagement element and said first pressure input port of said oil ejection control valve; and a supply pressure oil passage connected between a port of an oil chamber of said second hydraulic engagement element and said second pressure input port of said oil ejection control valve.
Claim 3
Dependent Claim
46 words
A hydraulic control device for an automatic automotive transmission system according to claim 1, wherein said first hydraulic engagement element is a hydraulic engagement element for a higher speed stage while said second hydraulic engagement element is a hydraulic engagement element for a lower speed stage.
Claim 4
Dependent Claim
29 words
A hydraulic control device for an automatic automotive transmission system according to claim 2, wherein said higher speed stage and said lower speed stage are two adjacent speed stages.
Claim 5
Dependent Claim
41 words
A hydraulic control device for an automatic automotive transmission system according to claim 2, wherein said higher speed stage and said lower speed stage are two speed stages which are separated from each other at least by one intermediate speed stage.
Claim 6
Dependent Claim
84 words
A hydraulic control device for an automatic automotive transmission system according to claim 4, wherein said oil ejection control valve is further provided with a third pressure input port for applying supply pressure for a hydraulic engagement element for establishing said intermediate speed stage to a third pressure receiving surface of said valve member so as to move said valve member in a direction to open a communication between said inlet port and said outlet port against a biasing force of said spring means.
Claim 7
Dependent Claim
46 words
A hydraulic control device for an automatic automotive transmission system according to claim 1, wherein said first hydraulic engagement element is a hydraulic engagement element for a lower speed stage while said second hydraulic engagement element is a hydraulic engagement element for a higher speed stage.
Claim 8
Dependent Claim
130 words
A hydraulic control device for an automatic automotive transmission system according to claim 6, further comprising: a switch valve interposed in said ejection pressure oil passage, and having an output port connected to said first pressure input port of said oil ejection control valve, a first input port connected to said port of said oil chamber of said first hydraulic engagement element, and a second input port connected to said port of said oil chamber of said second hydraulic engagement element; and means for switching over said switch valve according to a load condition of an engine of the vehicle so that said first pressure receiving surface receives said ejection pressure when the load condition of said engine is lighter than a prescribed level, and otherwise receives said supply pressure.