EP0045492A2 — Fail safe automatic transmission lock up clutch c…

Claim 1

Independent Claim 699 words

In an automatic transmission for an engine driven vehicle, comprising: (a) a gear transmission mechanism, which can provide a plurality of forward speed stages including a highest speed stage and a next to highest speed stage, and which comprises a plurality of hydraulic fluid pressure activated friction engaging mechanisms combinations of which are selectively actuated by selective supply of actuating hydraulic fluid pressures thereto so as to engage said plurality of speed stages, said plurality of hydraulic fluid pressure activated friction engaging mechanisms including a first friction engaging mechanism which is engaged by supply of a first actuating hydraulic fluid pressure thereto when and only when said gear transmission mechanism is providing its said highest speed stage and a second friction engaging mechanism which is engaged by supply of a second actuating hydraulic fluid pressure thereto when said gear transmission mechanism is providing its said next to highest speed stage but which is not engaged when said gear transmission mechanism is providing its said highest speed stage, said second actuating hydraulic fluid pressure not being present when said gear transmission mechanism is providing its said highest speed stage; (b) a torque converter, the interior of which is filled with hydraulic fluid, which comprises a lock up clutch and a first and a second hydraulic fluid channel, said lock up clutch being respectively selectively disengaged or engaged, according as to whether hydraulic fluid pressure is supplied to said first hydraulic fluid channel and is released from said second hydraulic fluid channel, or is supplied to said second hydraulic fluid channel and is released from said first hydraulic fluid channel: a transmission control system, comprising: (e) a source of regulated torque converter hydraulic fluid pressure for filling the inside of said torque converter with hydraulic fluid; (d) a hydraulic fluid pressure control system which controls said gear transmission mechanism by said selective supply of said combinations of said hydraulic fluid pressures including said first actuating hydraulic fluid pressure and said second actuating hydraulic fluid pressure thereto so as selectively to engage various ones of said plurality of speed stages, comprising a governor hydraulic fluid pressure control valve which produces a governor hydraulic fluid pressure which is representative of vehicle speed and which increases with increasing vehicle speed, and a throttle hydraulic fluid pressure control valve which produces a throttle hydraulic fluid pressure which is representative of the load on said engine of said vehicle and which increases with increasing engine load; and (e) a lock up clutch control valve, which has a first switched position and a second switched position, which when in its said first switched position switches said first hydraulic fluid channel so as to supply thereto a supply of said torque converter hydraulic fluid pressure and switches said second hydraulic fluid channel so as to release hydraulic fluid therefrom, and which when in its said second switched position, if the current value of said governor hydraulic fluid pressure is over a first predetermined pressure value, switches said second hydraulic fluid channel so as to supply thereto a supply of said torque converter hydraulic fluid pressure and switches said first hydraulic fluid channel so as to release hydraulic fluid therefrom, said lock up clutch control valve being switched to its said second switched position by supply of either a first control hydraulic fluid pressure or a second control hydraulic fluid pressure thereto, and being always switched to its said first switched position in the simultaneous absence of said first and said second control hydraulic fluid pressures; (f) said first control hydraulic fluid pressure being provided to said lock up clutch control valve when and only when said governor hydraulic fluid pressure is higher than a second predetermined pressure value which is higher than said first predetermined pressure value and also said first actuating hydraulic fluid pressure is present; and (g) said second control hydraulic fluid pressure being provided to said lock up clutch control valve, if the current value of said governor hydraulic fluid pressure is over said first predetermined pressure value, when and only when said throttle hydraulic fluid pressure is lower than a third predetermined pressure value and also said second actuating hydraulic fluid pressure is present.

Claim 2

Dependent Claim 699 words

In an automatic transmission for an engine driven vehicle, comprising: (a) a gear transmission mechanism, which can provide a plurality of forward speed stages including a highest speed stage and a next to highest speed stage, and which comprises a plurality of hydraulic fluid pressure activated friction engaging mechanisms combinations of which are selectively actuated by selective supply of actuating hydraulic fluid pressures thereto so as to engage said plurality of speed stages, said plurality of hydraulic fluid pressure activated friction engaging mechanisms including a first friction engaging mechanism which is engaged by supply of a first actuating hydraulic fluid pressure thereto when and only when said gear transmission mechanism is providing its said highest speed stage and a second friction engaging mechanism which is engaged by supply of a second actuating hydraulic fluid pressure thereto when said gear transmission mechanism is providing its said next to highest speed stage but which is not engaged when said gear transmission mechanism is providing its said highest speed stage, said second actuating hydraulic fluid pressure not being present when said gear transmission mechanism is providing its said highest speed stage; (b) a torque converter, the interior of which is filled with hydraulic fluid, which comprises a lock up clutch and a first and a second hydraulic fluid channel, said lock up clutch being respectively selectively disengaged or engaged, according as to whether hydraulic fluid pressure is supplied to said first hydraulic fluid channel and is released from said second hydraulic fluid channel, or is supplied to said second hydraulic fluid channel and is released from said first hydraulic fluid channel: a transmission control system, comprising: (e) a source of regulated torque converter hydraulic fluid pressure for filling the inside of said torque converter with hydraulic fluid; (d) a hydraulic fluid pressure control system which controls said gear transmission mechanism by said selective supply of said combinations of said hydraulic fluid pressures including said first actuating hydraulic fluid pressure and said second actuating hydraulic fluid pressure thereto so as selectively to engage various ones of said plurality of speed stages, comprising a governor hydraulic fluid pressure control valve which produces a governor hydraulic fluid pressure which is representative of vehicle speed and which increases with increasing vehicle speed, and a throttle hydraulic fluid pressure control valve which produces a throttle hydraulic fluid pressure which is representative of the load on said engine of said vehicle and which increases with increasing engine load; and (e) a lock up clutch control valve, which has a first switched position and a second switched position, which when in its said first switched position switches said first hydraulic fluid channel so as to supply thereto a supply of said torque converter hydraulic fluid pressure and switches said second hydraulic fluid channel so as to release hydraulic fluid therefrom, and which when in its said second switched position, if the current value of said governor hydraulic fluid pressure is over a first predetermined pressure value, switches said second hydraulic fluid channel so as to supply thereto a supply of said torque converter hydraulic fluid pressure and switches said first hydraulic fluid channel so as to release hydraulic fluid therefrom, said lock up clutch control valve being switched to its said second switched position by supply of either a first control hydraulic fluid pressure or a second control hydraulic fluid pressure thereto, and being always switched to its said first switched position in the simultaneous absence of said first and said second control hydraulic fluid pressures; (f) said first control hydraulic fluid pressure being provided to said lock up clutch control valve when and only when said governor hydraulic fluid pressure is higher than a second predetermined pressure value which is higher than said first predetermined pressure value and also said first actuating hydraulic fluid pressure is present; and (g) said second control hydraulic fluid pressure being provided to said lock up clutch control valve, if the current value of said governor hydraulic fluid pressure is over said first predetermined pressure value, when and only when said throttle hydraulic fluid pressure is lower than a third predetermined pressure value and also said second actuating hydraulic fluid pressure is present.

Claim 3

Dependent Claim 119 words

A transmission control system according to claim 1, wherein said lock up .clutch control valve, when in its said second switched position, if and only if the current value of said governor hydraulic fluid pressure is over said first predetermined pressure value, switches said second hydraulic fluid channel so as to supply thereto a supply of said torque converter hydraulic fluid pressure and switches said first hydraulic fluid channel so as to release hydraulic fluid therefrom; and otherwise when in its said second switched position switches said first hydraulic fluid channel so as to supply thereto a supply of said torque converter hydraulic fluid pressure and switches said second hydraulic fluid channel so as to release hydraulic fluid therefrom.

Claim 4

Dependent Claim 67 words

A transmission control system according to claim 1, wherein said second control hydraulic fluid pressure is provided to said lock up Clutch .control valve, when and only when the current value of said governor hydraulic fluid pressure is over said first predetermined pressure value, said throttle hydraulic fluid pressure is lower than a third predetermined pressure value, and also said second actuating hydraulic fluid pressure is present.

Claim 5

Dependent Claim 181 words

A transmission control system according to claim 1, wherein said lock up clutch control valve comprises a housing within which is formed a bore, and a valve spool member and a piston member coaxially fitted within said bore so as to abut against one another by their ends; a first chamber being defined at the end of said piston member remote from said valve spool member, and a second chamber being defined around the meeting ends of said valve spool member and said piston member; said valve spool member being biased in the direction towards said first chamber; and one of said first and said second control hydraulic fluid pressures being supplied to said first chamber, while the other is supplied to said second chamber; said first switched position of said lock up clutch control valve being the state thereof in which said valve spool member is biased towards said first chamber, while said second switched position of said lock up clutch control valve is the state thereof in which said valve spool member is biased away from said first chamber.

Claim 6

Dependent Claim 213 words

A transmission control system according to claim 1, further comprising a first lock up clutch interrupt valve which has a first switched position and a second switched position, which when in its said first switched position switches a supply of said first actuating hydraulic fluid pressure so as to supply said first actuating hydraulic fluid pressure to said lock up clutch control valve as said first control hydraulic fluid pressure, and which when in its said second switched position does not switch said supply of said first actuating hydraulic fluid pressure so as to supply said first actuating hydraulic fluid pressure to said lock up clutch control valve as said first control hydraulic fluid pressure, so that said lock up clutch control valve in this case is not supplied with any such first control hydraulic fluid pressure; said first lock up clutch interrupt valve being supplied with said governor hydraulic fluid pressure by said hydraulic fluid pressure control system, and being switched to its said second switched position when the pressure value of said governor hydraulic fluid pressure is less than said second predetermined pressure value, while being switched to its said first switched position when the pressure value of said governor hydraulic fluid pressure is greater than said second predetermined pressure value.

Claim 7

Dependent Claim 239 words

. A transmission control system according to claim 5, wherein said first lock up clutch interrupt valve comprises a valve element which has a first position and a second position, and a means for biasing said valve element towards its said second position; -said first switched position of said first lock up clutch interrupt valve being the state thereof in which said valve element is in its said first switched position, and said second switched position of said first lock up clutch interrupt valve being the state thereof in which said valve element is in its said second switched position; said governor hydraulic fluid pressure acting on said valve element so as to bias said valve element towards its said first position; said first lock up clutch interrupt valve being further formed with an input port which is supplied with said first actuating hydraulic fluid pressure, when it is present, by said hydraulic fluid pressure control system, and an output port which is communicated with said lock up clutch control valve so that hydraulic fluid pressure present at said output port is supplied to said lock up clutch control valve as said first control hydraulic fluid pressure; said input port being communicated to said output port when said valve element is in its said first position; and said input port being put out of communication with said output port when said valve element is in its said second position.

Claim 8

Dependent Claim 40 words

A transmission control system according to claim 6, wherein said first lock up clutch interrupt valve is further formed with a drain port which is communicated to said output port when said valve element is in its said second position.

Claim 9

Dependent Claim 337 words

A transmission control system according to claim 1, further comprising a second lock up clutch interrupt valve which has a first switched position and a second switched position, which when in its said first switched position switches supply of said second actuating hydraulic fluid pressure so as to supply said second actuating hydraulic fluid pressure towards said lock up clutch control valve as said second control hydraulic fluid pressure, and which when in its said second switched position does not switch said supply of said second actuating hydraulic fluid pressure so as to supply said second actuating hydraulic fluid pressure towards said lock up clutch control valve as said second control hydraulic fluid pressure, so that said lock up clutch control valve in this case is not supplied with any such second control hydraulic fluid pressure; said second lock up clutch interrupt valve being supplied by said hydraulic fluid pressure control system with a third actuating hydraulic fluid pressure, when it is present, and when not so supplied being positively switched to its said second switched position. irrespective of any other control pressures supplied thereto; said second lock up clutch interrupt valve further being supplied with said throttle hydraulic fluid pressure by said hydraulic fluid pressure control system; and, when said second lock up clutch interrupt valve is being supplied with said third actuating hydraulic fluid pressure, said second lock up clutch interrupt valve being switched to its said first switched position when the pressure value of said throttle hydraulic fluid pressure is less than said third predetermined pressure value and being switched to its said second switched position when the pressure value of said throttle hydraulic fluid pressure is greater than said third predetermined pressure value; said supply of said second actuating hydraulic fluid pressure which is being supplied towards said lock up clutch control valve as said second control hydraulic fluid pressure being intercepted, if and only if the current value of said governor hydraulic fluid pressure is not over said first predetermined pressure value.

Claim 10

Dependent Claim 260 words

A transmission control system according to claim 8, wherein said second lock up clutch interrupt valve comprises a valve element which has a first position and a second position, and a means for biasing said valve element towards its said second position; said first switched position of said second lock up clutch interrupt valve being the state thereof in which said valve element is in its said first switched position, and said second switched position of said second lock up clutch interrupt valve being the state thereof in which said valve element is in its said second switched position; said throttle hydraulic fluid pressure acting on said valve element so as to bias said valve element towards its said second position; said second actuating hydraulic fluid pressure, when present, acting on said valve element so as to bias said valve element towards its said first position; said lock up clutch interrupt valve being further formed with an input port which is supplied with said source hydraulic fluid pressure, when it is present, by said hydraulic fluid pressure control system, and an output port which communicates towards said lock up clutch control valve so that hydraulic fluid pressure present at said output port is supplied towards said lock up clutch control valve as said second control hydraulic fluid pressure; said input port being communicated to said output port when said valve element is in its said first position; and said input port being put out of communication with said output port when said valve element is in its said second position.

Claim 11

Dependent Claim 39 words

A transmission control system according to claim 9, said second lock up clutch interrupt valve being further formed with a drain port which is communicated to said output port when said valve element is in its said second position.

Claim 12

Dependent Claim 196 words

A transmission control system according to claim 1, further comprising a fail safe valve which has a first switched position and a second switched position, and which when said lock up clutch control valve is in its said second switched position is communicated via said lock up clutch control valve to said first and said second hydraulic fluid channels; at which time said fail safe valve: when in its said first switched position, switches said first hydraulic fluid channel so as to supply thereto a supply of said torque converter hydraulic fluid pressure and switches said second hydraulic fluid channel so as to release hydraulic fluid therefrom; and, when in its said second switched position, switches said second hydraulic fluid channel so as to supply thereto a supply of said torque converter hydraulic fluid pressure and switches said first hydraulic fluid channel so as to release hydraulic fluid therefrom; said fail safe valve being switched to its said second switched position when governor hydraulic fluid pressure is greater than said first predetermined pressure value, and being switched to its said first switched position when governor hydraulic fluid pressure is less than said first predetermined pressure value.

Claim 13

Dependent Claim 109 words

A transmission control system according to claim 11, wherein further said fail safe valve controls supply of said second control hydraulic fluid pressure to said lock up clutch control valve; said fail safe valve, when in its said first position, interrupting said supply of said second control hydraulic fluid pressure to said lock up clutch control valve, so that at this time said lock up clutch control valve is definitely not supplied with said second control hydraulic fluid pressure; and said fail safe valve, when in its said second position, allowing communication of said supply of said second control hydraulic fluid pressure to said lock up clutch control valve.

Fail safe automatic transmission lock up clutch control system

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