Hydraulic controlling system for lockup clutches

Claim 2

A hydraulic control system for a lockup clutch comprising: an oil pressure supply source; regulator means for providing a secondary oil pressure; a fluid coupling hydraulically transmitting an engine power to an automatic transmission; a lockup clutch disposed in the fluid coupling, the lockup clutch defining an apply chamber and a release chamber; a lockup control valve for controlling an amount of engagement of the lockup clutch by a pressure differential between oil pressure in the apply chamber and oil pressure in the release chamber, the lockup control valve having a spool biased by a constant pressure means with first, second, third and fourth oil chambers being formed by the spool; a solenoid valve disposed in an oil path between the first oil chamber and the oil pressure supply source; the second oil chamber connecting the release chamber to the secondary oil pressure and an exhaust port; the third oil chamber connecting the apply chamber to the secondary oil pressure; the fourth oil chamber being connected to the secondary oil pressure; and each of the second and fourth oil chambers having a pressure-receiving face, the second chamber pressure-receiving face and the fourth chamber pressure-receiving face having identical surface areas and respectively acting in a direction of the constant pressure means and a direction opposite thereto.

Claim 3

A hydraulic control system for a lockup clutch as claimed in claim 1, wherein the constant pressure means is at least one of a spring and oil pressure from the oil pressure supply source.

Claim 4

A hydraulic control system for a lockup clutch as claimed in claim 1, wherein the constant pressure means is a spring disposed in the fourth oil chamber.

Claim 5

A hydraulic control system as claimed in claim 1, wherein the pressure-receiving faces are arranged to maintain a constant pressure differential across the lockup clutch so that, during slip control, action of the second chamber pressure-receiving face in the direction of constant pressure means less engagement of the lockup clutch and action of the fourth chamber pressure-receiving face in the direction opposite of the constant pressure means causes more engagement of the lockup clutch.

Claim 6

A hydraulic control system as claimed in claim 4, wherein the secondary oil pressure provides oil under equal pressure to the second and fourth chambers.

Claim 7

A hydraulic control system as claimed in claim 1, wherein each of the second and fourth oil chambers have an additional pressure-receiving face, the fourth chamber additional pressure-receiving face and the second chamber additional pressure-receiving face having identical surface areas and respectively acting in the direction of the constant pressure means and the direction opposite thereto.

Claim 8

A hydraulic control system for a lockup clutch comprising: an oil pressure supply source; regulator means for supplying secondary oil pressure; a fluid coupling for hydraulically transmitting an engine power to an automatic transmission; a lockup clutch disposed in the fluid coupling, the lockup clutch defining an apply chamber and a release chamber; a lockup control valve for controlling an amount of engagement of the lockup clutch by a pressure differential between oil pressure in the apply chamber and oil pressure in the release chamber, the lockup control valve having a spool biased by a constant pressure means with first, second and third oil chambers being formed by the spool; a solenoid valve disposed in an oil path between the first oil chamber and the oil pressure supply source; the second oil chamber connecting the release chamber to the secondary oil pressure and an exhaust port; the third oil chamber being connected to the secondary oil pressure; and each of the second and third oil chambers having a pressure-receiving face, the second chamber pressure-receiving face and the third chamber pressure-receiving face having identical surface areas and respectively acting in a direction of the constant pressure means and a direction opposite thereto during slip control.

Claim 9

A hydraulic control system for a lockup clutch comprising: an oil pressure supply source; regulator means for supplying secondary oil pressure; a fluid coupling for hydraulically transmitting an engine power to an automatic transmission; a lockup clutch disposed in the fluid coupling, the lockup clutch defining an apply chamber and a release chamber; a lockup control valve for controlling an amount of engagement of the lockup clutch by a pressure differential between oil pressure in the apply chamber and oil pressure in the release chamber, the lockup control valve having a spool biased by a constant pressure means with first, second and third oil chambers being formed by the spool; a solenoid valve disposed in an oil path between the first oil chamber and the oil pressure supply source; the second oil chamber connecting the release chamber to the secondary oil pressure and an exhaust port; the third oil chamber being connected to the secondary oil pressure; and each of the second and third oil chambers having a pressure-receiving face, the second chamber pressure-receiving face and the third chamber pressure-receiving face having identical surface areas and respectively acting in a direction of the constant pressure means and a direction opposite thereto during slip control.

Claim 10

A hydraulic control system for a lockup clutch as claimed in claim 7, wherein the constant pressure means is at least one of a spring and oil pressure from the oil pressure supply source.

Claim 11

A hydraulic control system for a lockup clutch as claimed in claim 7, wherein the constant pressure is a spring disposed in the first oil chamber.

Claim 12

A hydraulic control system as claimed in claim 7, wherein each of the second and third oil chambers have an additional pressure-receiving face, the third chamber additional pressure-receiving face and the second chamber additional pressure-receiving face having identical surface areas and respectively acting in the direction of the constant pressure means and the direction opposite thereto.

Claim 13

A hydraulic control system as defined in claim 7 wherein the apply chamber defined by the lockup clutch is directly coupled to the secondary oil pressure.

Claim 14

A hydraulic control system for a lockup clutch comprising: an oil pressure supply source; regulator means for supplying secondary oil pressure; a fluid coupling for hydraulically transmitting an engine power to an automatic transmission; a lockup clutch disposed in the fluid coupling, the lockup clutch defining an apply chamber and a release chamber; a lockup control valve for controlling an amount of engagement of the lockup clutch by a pressure differential between oil pressure in the apply chamber and oil pressure in the release chamber, the lockup control valve having a spool biased by a constant pressure means with first, second and third oil chambers being formed by the spool; a solenoid valve disposed in an oil path between the first oil chamber and the oil pressure supply source; the second oil chamber connecting the release chamber to the secondary oil pressure and an exhaust port; the third oil chamber being connected to the secondary oil pressure; and each of the second and third oil chambers having a pressure-receiving face, the second chamber pressure-receiving face and the third chamber pressure-receiving face having identical surface areas and respectively acting in a direction of the constant pressure means and a direction opposite thereto, wherein the pressure-receiving faces are arranged to maintain a constant pressure differential across the lockup clutch so that, during slip control, action of the second chamber pressure-receiving face in the direction of constant pressure means causes less engagement of the lockup clutch and action of the third chamber pressure-receiving face in the direction opposite of the constant pressure means causes more engagement of the lockup clutch.

Claim 15

A hydraulic control system for a lockup clutch comprising: an oil pressure supply source; regulator means for supplying secondary oil pressure; a fluid coupling for hydraulically transmitting an engine power to an automatic transmission; a lockup clutch disposed in the fluid coupling, the lockup clutch defining an apply chamber and a release chamber; a lockup control valve for controlling an amount of engagement of the lockup clutch by a pressure differential between oil pressure in the apply chamber and oil pressure in the release chamber, the lockup control valve having a spool biased by a constant pressure means with first, second and third oil chambers being formed by the spool; a solenoid valve disposed in an oil path between the first oil chamber and the oil pressure supply source; the second oil chamber connecting the release chamber to the secondary oil pressure and an exhaust port; the third oil chamber being connected to the secondary oil pressure; and each of the second and third oil chambers having a pressure-receiving face, the second chamber pressure-receiving face and the third chamber pressure-receiving face having identical surface areas and respectively acting in a direction of the constant pressure means and a direction opposite thereto, wherein the pressure-receiving faces are arranged to maintain a constant pressure differential across the lockup clutch so that, during slip control, action of the second chamber pressure-receiving face in the direction of constant pressure means causes less engagement of the lockup clutch and action of the third chamber pressure-receiving face in the direction opposite of the constant pressure means causes more engagement of the lockup clutch.

Claim 16

A hydraulic control system as claimed in claim 12, wherein the secondary oil pressure provides oil under equal pressure to the second and third chambers.