Abstract: A variable displacement oil pump for an internal combustion engine includes a pump element to vary inside volumes of pumping chambers to suck and discharge an oil, a varying mechanism to vary a pumping volume variation quantity of the pumping chambers, with movement of a movable member such as a cam ring, an urging mechanism to urge the movable member in a direction to increase the pumping volume variation quantity, first and second control oil chambers to urge the movable member to vary the pumping volume to variation quantity, and a control mechanism, such as a pilot valve, to control the supply/drainage of the oil to or from the second control oil chamber. An operation oil pressure of the movable member is set higher than an operation oil pressure of the control mechanism in a higher pressure region.

Abstract: Variable displacement oil pump for supplying oil to an internal combustion engine. Included is a cam ring having an inner peripheral section for accommodating the pump element thereinside, and an outer peripheral section having a swinging movement fulcrum. A control device for changeover controlling supply of a discharge pressure to first and second pressure chambers so the cam ring is swingingly movable to change an eccentricity amount of the cam ring relative to an axis of the rotor, wherein the first pressure receiving surface is set larger in pressure receiving area than the second pressure receiving surface, wherein a part of each of the first and second pressure chambers is disposed overlapping with the discharge region in a radial direction of the rotor, and wherein the first and second pressure chambers are disposed nearer to the swinging movement fulcrum than to the axis of the cam ring.

Abstract: Variable displacement oil pump for supplying oil to an internal combustion engine. Included is a cam ring having an inner peripheral section for accommodating the pump element thereinside, and an outer peripheral section having a swinging movement fulcrum. A control device for changeover controlling supply of a discharge pressure to first and second pressure chambers so the cam ring is swingingly movable to change an eccentricity amount of the cam ring relative to an axis of the rotor, wherein the first pressure receiving surface is set larger in pressure receiving area than the second pressure receiving surface, wherein a part of each of the first and second pressure chambers is disposed overlapping with the discharge region in a radial direction of the rotor, and wherein the first and second pressure chambers are disposed nearer to the swinging movement fulcrum than to the axis of the cam ring.

Abstract: A variable displacement oil pump for an automotive engine. The oil pump includes a cam ring accommodating thereinside a pump element having a rotor. The cam ring is swingingly movably accommodated in a housing and biased in a direction to increase an eccentricity amount of the cam ring relative to the axis of the rotor by a biasing member. First and second pressure chambers are defined inside the housing by the outer peripheral section of the cam ring. The first pressure chamber is supplied with a discharge pressure to be applied to the cam ring to oppose to a biasing force of the biasing member. The second pressure chamber is supplied with the discharge pressure to be applied to the cam ring to assist the biasing force of the biasing member. Additionally, a control device is provided for controlling supply of the discharge pressure to the second pressure chamber.

Abstract: A variable displacement pump includes: an urging mechanism which includes two spring members; an electromagnetic switching valve which is arranged to connect the second control chamber and the discharge portion in an energized state, and to connect the second control chamber and the low pressure chamber in a deenergized state; and a control valve which is actuated by the pressure of the discharge portion, and which is arranged to decrease the pressure within the second control chamber when the pressure of the discharge portion becomes equal to or greater than a predetermined pressure.

Abstract: Variable displacement oil pump includes a: rotor; vanes; cam ring; housing; biasing member biasing the cam ring in a direction enlarging an eccentricity between centers of the rotor and inner circumferential surface of the cam ring; a contact surface to contact with a cam ring outer circumferential surface via a biasing force applied to the cam ring by the biasing member; a control chamber separately formed by the contact surface and a swing fulcrum of the cam ring on a cam ring outer circumference when the contact surface contacts the cam ring outer circumferential surface, and causing the cam ring to swing against the biasing force of the biasing member by a pressure from a discharge portion to the control chamber; and a choking portion formed on the outer circumferential surface of the cam ring to maintain a pressure of the control chamber even when the cam ring swings.

Abstract: A variable displacement oil pump includes a rotor; a plurality of vanes; a cam ring; a housing; a biasing member configured to biases the cam ring in a direction that enlarges an eccentricity between a rotation center of the rotor and a center of inner circumferential surface of the cam ring; a contact surface configured to become in contact with an outer circumferential surface of the cam ring by means of a biasing force applied to the cam ring by the biasing member; a control chamber separately formed by the contact surface and a swing fulcrum of the cam ring on an outer circumference of the cam ring when the contact surface is in contact with the outer circumferential surface of the cam ring, and configured to cause the cam ring to swing against the biasing force of the biasing member by a pressure introduced from a discharge portion to the control chamber; and a choking portion formed on the outer circumferential surface of the cam ring so as to maintain a pressure of the control chamber even when the cam

Abstract: A variable displacement oil pump for an automotive engine. The oil pump includes a cam ring accommodating thereinside a pump element having a rotor. The cam ring is swingingly movably accommodated in a housing and biased in a direction to increase an eccentricity amount of the cam ring relative to the axis of the rotor by a biasing member. First and second pressure chambers are defined inside the housing by the outer peripheral section of the cam ring. The first pressure chamber is supplied with a discharge pressure to be applied to the cam ring to oppose to a biasing force of the biasing member. The second pressure chamber is supplied with the discharge pressure to be applied to the cam ring to assist the biasing force of the biasing member. Additionally, a control device is provided for controlling supply of the discharge pressure to the second pressure chamber.

Abstract: A variable displacement oil pump for an automotive engine. The oil pump includes a cam ring accommodating thereinside a pump element having a rotor. The cam ring is swingingly movably accommodated in a housing and biased in a direction to increase an eccentricity amount of the cam ring relative to the axis of the rotor by a biasing member. First and second pressure chambers are defined inside the housing by the outer peripheral section of the cam ring. The first pressure chamber is supplied with a discharge pressure to be applied to the cam ring to oppose to a biasing force of the biasing member. The second pressure chamber is supplied with the discharge pressure to be applied to the cam ring to assist the biasing force of the biasing member. Additionally, a control device is provided for controlling supply of the discharge pressure to the second pressure chamber.