Hydraulic pressure supply device for industrial vehicle

Abstract

A hydraulic pressure supply device for an industrial vehicle has a first hydraulic pump (1) and a second hydraulic pump (2) that are driven by an engine (E); a first hydraulic circuit (L1) for leading, as clutch control pressure, pressurized oil, which is supplied by the first hydraulic pump (1), to a transmission control device (3) after regulating the pressurized oil by a pressure regulation valve (21), leading as torque converter operation oil the pressurized oil, which has passed through the pressure regulation valve (21), to a torque converter (4), and further leading the pressurized oil, which has passed through the torque converter (4), to an oil cooler (23) ; a safety valve (22) connected to that part of the first hydraulic circuit (L1) which is between the pressure regulation valve (21) and the torque converter (4) and, if the pressure on the entrance side of the torque converter (4) is not lower than a predetermined value (P22), releasing that pressurized oil on the torque converter entrance side to a tank; a second hydraulic circuit (L2) for dividing pressurized oil from the second hydraulic pump (2) to a circuit portion that is downstream of the pressure regulation valve (21) and upstream of the safety valve (22) and to a circuit portion that is downstream of the torque converter (4) and upstream of the oil cooler (23); and a flow control section (24) for changing the proportion of the rate of flow in the second hydraulic circuit (L2) so that the proportion to a circuit part that is downstream of the torque converter (4) and upstream of the oil cooler (23) increases as the pressure at the entrance of the torque converter (4) increases.

Description

technical field [0001] The present invention relates to a hydraulic supply device for industrial vehicles. Background technique [0002] Conventionally, in industrial vehicles such as wheel loaders equipped with a hydraulic torque converter (hereinafter referred to as a torque converter), a device is known in which pressure oil from a hydraulic pump is used as working oil to guide hydraulic pressure. The torque converter is guided to a clutch control control valve of the transmission as a clutch control pressure (for example, refer to Patent Document 1). In the device described in Patent Document 1, a pressure regulating valve is provided in order to make the clutch control pressure supplied to the control valve a predetermined set pressure. The torque converter, and then guide the pressure oil that has passed through the torque converter to the oil cooler. Between the pressure regulating valve and the torque converter, a safety valve is interposed to limit the inlet press...

AI Technical Summary

Problems solved by technology

However, in the device described in the aforementioned Patent Document 1, simply increasing the pump discharge rate increases the oil temperature due to an increase in the amount of oil passing through the safety valve, so the increase in oil temperature cannot be effectively suppressed.

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