Discharge port (26) as arc-recessed discharge portion is formed by cutting on bottom surface (13a) of pump accommodating portion (13) of variable displacement pump. On mounting surface (1b) of housing body (1), first low pressure chamber (281) is formed at position overlapping with discharge port (26) in radial direction of pump structure (14) formed by driving shaft (3), rotor (4) and vanes (5) Drain hole (28b) communicating with low pressure portion located outside housing body (1) is formed on bottom surface (28a) of first low pressure chamber (281) along direction of rotation axis (O1) of pump structure (14). Low pressure portion has pressure that is hydraulic pressure of oil discharged from discharge port (26) or less. Oil from discharge port (26), having higher pressure than first low pressure chamber (281), flows into first low pressure chamber (281) by pressure difference between discharge port (26) and first low pressure chamber (281).

The present invention relates to an arrangement for detecting a delivery volume and/or a delivery flow, with a discontinuously operating pump (1), at least one outlet line (3) and/or one inlet line (2, 2-1, 2-2) and a passive valve (5, 5-1, 5-2), which is arranged in the outlet line (3) or the inlet line (2, 2-1, 2-2) and which has a valve seat (15-1, 15-2) and a valve head (16-1, 16-2), the valve (5, 5-1, 5-2) being closed in a first position of the valve head (16-1, 16-2) and being open in a second position of the valve head (16-1, 16-2) of the valve (5, 5-1, 5-2). The arrangement according to the invention is defined by a sensor (8, 8-1, 8-2), by means of which values can be detected which indicate whether the valve head (16-1, 16-2) is in the first or the second position, and by a computing unit (9) which is coupled to the sensor (8, 8-1, 8-2) and by means of which the volume delivered by the pump (1) and/or the delivery flow of the pump (1) can be calculated on the basis of the detected values of the sensor (8, 8-1, 8-2). The invention relates furthermore, to an extraction system for a plant protective with such an arrangement and to a method for detecting a delivery volume and/or a delivery flow of a discontinuously operating pump, which method can be carried out by this arrangement.

A motor-driven fluid pump has a positive displacement rotary pumping element with an offset circular cam carried outwardly of the element, the cam being rotated with the pumping element by contact with pistons carried radially by the pumping element. Ends of the pistons are spherical and bear directly on the cam's inner surface. During breaking in of each pump, the piston ends wear a single concave groove in the inner surface of the cam, which helps to stabilize the pistons. The pump maintains a constant mass flow rate for a given input command by adjusting for fluid type, measured fluid operating temperature, and changing motor speed. The pump also maintains a constant flow output for its life by adjusting for internal wear; it also predicts its remaining life by comparing its current motor speed for a given flow against the maximum allowable motor speed.

A motor-driven fluid pump has a positive displacement rotary pumping element with an offset circular cam carried outwardly of the element, the cam being rotated with the pumping element by contact with pistons carried radially by the pumping element. Ends of the pistons are spherical and bear directly on the cam's inner surface. During breaking in of each pump, the piston ends wear a single concave groove in the inner surface of the cam, which helps to stabilize the pistons. The pump maintains a constant mass flow rate for a given input command by adjusting for fluid type, measured fluid operating temperature, and changing motor speed. The pump also maintains a constant flow output for its life by adjusting for internal wear; it also predicts its remaining life by comparing its current motor speed for a given flow against the maximum allowable motor speed.

An example crescent seal assembly comprises: an outer crescent of a gear pump; an inner crescent of the gear pump mating with the outer crescent such that an exterior peripheral surface of the inner crescent interfaces with an interior peripheral surface of the outer crescent, forming: (i) a spring cavity, (ii) a first check valve cavity, and (iii) a second check valve cavity therebetween; a spring disposed in the at least one spring cavity; a first check pin disposed in the first check valve cavity; and a second check pin disposed in the second check valve cavity.

An example crescent seal assembly comprises: an outer crescent of a gear pump; an inner crescent of the gear pump mating with the outer crescent such that an exterior peripheral surface of the inner crescent interfaces with an interior peripheral surface of the outer crescent, forming: (i) a spring cavity, (ii) a first check valve cavity, and (iii) a second check valve cavity therebetween; a spring disposed in the at least one spring cavity; a first check pin disposed in the first check valve cavity; and a second check pin disposed in the second check valve cavity.

A hydrostatic transmission system includes a hydraulic motor and at least one proportional control valve and at least one pump connected to the hydraulic motor to provide fluid to operate the hydraulic motor. The at least one pump includes at least one fluid driver having a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from the pump inlet to the pump outlet. The hydrostatic transmission system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover and concurrently establishes an opening of the at least one proportional control valve to adjust at least one of a flow and a pressure in the hydrostatic transmission system to an operational set point.

A hydrostatic transmission system includes a hydraulic motor and at least one proportional control valve and at least one pump connected to the hydraulic motor to provide fluid to operate the hydraulic motor. The at least one pump includes at least one fluid driver having a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from the pump inlet to the pump outlet. The hydrostatic transmission system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover and concurrently establishes an opening of the at least one proportional control valve to adjust at least one of a flow and a pressure in the hydrostatic transmission system to an operational set point.

Variable capacity vane pump 1 supplying working fluid to power steering device of vehicle has pump housing 2 formed from bottomed cylindrical-shaped front housing 5 and rear housing 6 closing the front housing, pump element 3 accommodated in pump housing, communicating with inlet passage 23 and with outlet passage 30 and sucking and discharging working fluid, and flow amount control valve 33 controlling an amount of working fluid discharged by pump element. Pressure-sensitive valve 50, which changes a flow passage cross-sectional area of the outlet passage so that the discharge amount of the pump element is increased with increase in load pressure of power steering device, is set at some midpoint of the outlet passage and at bottom wall portion 5b of front housing. It is therefore possible to suppress increase in size of device while reducing energy loss when variable capacity vane pump is mounted in power steering device.

Variable capacity vane pump 1 supplying working fluid to power steering device of vehicle has pump housing 2 formed from bottomed cylindrical-shaped front housing 5 and rear housing 6 closing the front housing, pump element 3 accommodated in pump housing, communicating with inlet passage 23 and with outlet passage 30 and sucking and discharging working fluid, and flow amount control valve 33 controlling an amount of working fluid discharged by pump element. Pressure-sensitive valve 50, which changes a flow passage cross-sectional area of the outlet passage so that the discharge amount of the pump element is increased with increase in load pressure of power steering device, is set at some midpoint of the outlet passage and at bottom wall portion 5b of front housing. It is therefore possible to suppress increase in size of device while reducing energy loss when variable capacity vane pump is mounted in power steering device.