Hydraulic regulating system for a vehicle transmission
AssigneeVolvo Lastvagnar AB
InventorSverker Alfredsson
Life of this patent
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Abstract
Hydraulic control system for a vehicle transmission connected to an output shaft from a hydraulic torque converter (1) with a hydraulically operated disc clutch for locking the torque converter and which has two hydraulically operated disc clutches for shifting. The control system has a low pressure circuit (30) with a low-pressure pump feeding fluid through the torque converter, and a high pressure circuit (34) with a high-pressure pump (35), which feeds fluid via valves (38) to the disc clutches. The high-pressure pump has variable displacement, which is regulated by the operating pressure of the disc clutch of the torque converter, so that the high-pressure pump is set to a lower displacement when this last-mentioned clutch is engaged than when it is disengaged.
Claims5
Hydraulic control system for a vehicle transmission (20), connected to an output shaft (6) from a hydraulic torque converter (1) with a hydraulically operated friction clutch (7) for locking up the torque converter and which has at least two hydraulically operated clutch units (14,15) for shifting between the various gear speeds of the transmission, comprising a first hydraulic pump (31), which feeds, via a counterbalance valve (45), oil at low pressure to the torque converter, and a second hydraulic pump (35) which feeds, via regulator valve means (38), oil at high pressure to first, second and third piston-cylinder devices (10,9;
- 24,23;
- 26,25), each operating an individual one of said friction clutch and clutch units, characterized in that the second pump (35) is a high-pressure pump with variable displacement, which is controlled by a pressure-regulator valve (39), and that means (43, 44) are arranged to control the pressure-regulator valve to set the variable pump at maximum displacement when the friction clutch (7) is disengaged, and to a lower displacement when the friction clutch is engaged.
Dependencies are inferred from the claim text.