Hydraulic control unit for a hydraulic power transmission

摘要

A hydraulic control unit provided with oil pumps includes a first oil discharging outlet and a second oil discharging outlet, a high pressure route connected with the first oil discharging outlet, a medium pressure route with an oil pressure therein being lower than that in the high pressure route, a low pressure route with an oil pressure therein being lower than that in the medium pressure route, and a connection mode switching mechanism for selectively connecting a second oil discharging outlet with the high pressure route, the medium pressure route or the low pressure route. The connection mode switching mechanism includes a changeover valve selectively connecting the second oil discharging outlet with the medium pressure route or the low pressure route; and a changeover valve controlling device connecting the second oil discharging outlet with any of the medium pressure route and the low pressure route. The hydraulic control unit can minimize drive loss of an oil pump.