Variable capacity oil pump

Abstract

A variable capacity oil pump controlling a pump discharge pressure to a two-stage characteristic includes: an electromagnetic switching valve formed to enable a switching between a state in which oil is discharged from a second control oil chamber and a state in which oil is introduced into the second control oil chamber; a pilot valve controlled by a discharge pressure by oil and a biasing force by a control spring and configured to supply a hydraulic pressure to a first control oil chamber in accordance with oil, to interrupt the supply of the hydraulic pressure, and to supply or exhaust the hydraulic pressure to or from second control oil chamber; and an intermediate passage. Oil exhausted from the first and second control oil chambers is not introduced into an inside of a control spring housing chamber in which a control spring of the pilot valve is arranged.

1 . A variable capacity oil pump comprising:
 a pump constituting member which operatively discharges a working oil sucked from a suction section through a discharge section, with a volume of a plurality of pump chambers varied by a rotational drive through an internal combustion engine;   a movable member which is operatively moved to modify a volume variation quantity of the plurality of pump chambers according to a movement of the movable member;   a biasing mechanism which is installed in a state in which a set load is provided to bias the movable member in a direction in which the volume variation quantity of the plurality of pump chambers is increased;   a first control oil chamber configured to act a force in a direction in which the volume variation quantity of the plurality of pump chambers is decreased upon the movable member in response to a supply of the working oil into the first control oil chamber;   a second control oil chamber configured to act a force in a direction in which the volume variation quantity of the plurality of pump chambers is increased upon the movable member in response to a supply of the working oil into the second control oil chamber;   a switching mechanism formed to enable a switching between a state in which the working oil from the second control oil chamber is exhausted and another state in which the working oil is introduced into the second control oil chamber; and   a control mechanism configured to take a state in which the working oil within the first control oil chamber is exhausted and another state in which the working oil whose pressure is decreased than a discharge pressure from the discharge section is introduced into the first control oil chamber and to perform a pressure regulation for the working oil while applying the pressure to the working oil within the first control oil chamber by introducing the working oil into the first control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the state in which the working oil is exhausted from the second control oil chamber, and to take a further another state in which the working oil whose pressure is decreased than the discharge pressure from the discharge section is introduced into the second control oil chamber and a still further another state in which an introduction of the working oil into the second control oil chamber via the switching mechanism is interrupted and the working oil within the second control oil chamber is exhausted and to perform the pressure so regulation for the working oil while reducing the pressure to the working oil within the second control oil chamber by exhausting the working oil within the second control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the other state in which the working oil is introduced into the second control oil chamber, wherein the control mechanism is controlled by a hydraulic pressure of the working oil and a biasing force of a biasing member and the working oil is not introduced into a location of the control mechanism at which the biasing member is arranged.   
     
     
         2 . The variable capacity oil pump as claimed in  claim 1 , wherein the control mechanism includes: a valve body having an introduction port through which the hydraulic pressure of the working oil discharged from the discharge section is introduced, a first control port communicated with the first control oil chamber, a second control port communicated with the second control oil chamber, and a drain port communicated with a connection port and a low pressure section connected to the switching mechanism; a spool valve slidably housed in an axial one end side of the valve body to switch between a communication state of the introduction port and the connection port with respect to the first control oil chamber and a communication state of the connection port and the drain port with respect to the second control oil chamber; and a control spring which is the biasing member and housed in the axial other end side of the valve body to blase the spool valve toward the axial one end of the valve body according to its biasing force smaller than that of the biasing mechanism. 
     
     
         3 . The variable capacity oil pump as claimed in  claim 2 , wherein the spool valve includes large-diameter land sections which slide together with the valve body and disposed at both axial ends of the spool valve and a small diameter section is formed between each of the land sections and the connection port is appropriately communicated with the first control oil chamber and the connection port and the drain port are appropriately communicated with the second control oil chamber, via an outer periphery of the small diameter section. 
     
     
         4 . The variable capacity oil pump as claimed in  claim 3 , wherein the introduction port is disposed on the axial one end of the valve body and a pressure receiving surface upon which the hydraulic pressure of the working oil is acted is formed on the spool valve at an axial end section of the introduction port side of the spool valve. 
     
     
         5 . The variable capacity oil pump as claimed in  claim 4 , wherein the first control port, the second control port, and the drain port are formed in a peripheral wall of the valve body to be penetrated through the peripheral wall of the valve body. 
     
     
         6 . The variable capacity oil pump as claimed in  claim 5 , wherein the spool valve is formed in a solid manner. 
     
     
         7 . The variable capacity oil pump as claimed in  claim 5 , wherein a cylindrical convex section whose diameter is smaller than each of the land sections is projected at an end surface side of each of the land sections at the control spring side thereof and the one end side of the control spring is held by the convex section. 
     
     
         8 . The variable capacity oil pump as claimed in  claim 7 , wherein the control spring is supported on an inner peripheral wall of the valve body. 
     
     
         9 . The variable capacity oil pump as claimed in  claim 5 , wherein a cylindrical recess section whose diameter is smaller than each of the land sections is recessed toward the introduction port side at one end surface of each of the land sections and the one end side of the control spring is held by the recess section. 
     
     
         10 . The variable capacity oil pump as claimed in  claim 5 , wherein a tubular member in a bottomed cylindrical shape is arranged at an end section of the valve body at the control spring side thereon and the other end side of the control spring is held on the inner peripheral surface of the tubular member. 
     
     
         11 . The variable capacity oil pump as claimed in  claim 3 , wherein, in a case of a state in which the working oil is simultaneously exhausted from the first and second control oil chambers, the working oil is exhausted via the switching mechanism after passing through an outer periphery of the small diameter section. 
     
     
         12 . The variable capacity oil pump as claimed in  claim 1 , wherein the switching mechanism is an electrically switching controlled electromagnetic control valve. 
     
     
         13 . The variable capacity oil pump as claimed in  claim 12 , wherein the electromagnetic control valve takes a non-power receiving state when the working oil is introduced into the second control oil chamber and takes a power receiving state when the working oil is exhausted from the second control oil chamber. 
     
     
         14 . The variable capacity oil pump as claimed in  claim 13 , wherein the electromagnetic control valve carries out the switching between the supply and the exhaust of the working oil with respect to the second control oil chamber through a ball valve. 
     
     
         15 . The variable capacity oil pump as claimed in  claim 1 , wherein the working oil discharged from the discharge section is used in a form of a lubricating oil which lubricates a constituting member that the internal combustion engine internally has. 
     
     
         16 . The variable capacity oil pump as claimed in  claim 1 , wherein the working oil discharged from the discharge section is used for an oil jet from which the working oil is supplied to a driving source of a variably operated valve system and a piston of the internal combustion engine. 
     
     
         17 . A variable capacity oil pump comprising:
 a rotor configured to be drivingly rotated by an internal combustion engine;   a plurality of vanes movable out and into an outer peripheral section of the rotor;   a cam ring configured to partition an inner peripheral side of the cam ring into a plurality of pump chambers while accommodating the rotor and the vanes into an inner peripheral side of the cam ring, to move to vary an eccentricity quantity with respect to an axial center of the rotor, and thereby to vary a volume variation quantity of the plurality of pump chambers;   a suction section which is open to a suction region of the plurality of pump chambers in which a volume is increased in association with a rotation of the rotor;   a discharge section which is open to a discharge region of the plurality of pump chambers in which the volume is decreased in association with the rotation of the rotor;   a biasing mechanism disposed to have a set load and to bias the cam ring in a direction in which the eccentricity quantity becomes large;   a first control oil chamber configured to act a force in a direction in which the eccentricity quantity becomes small upon the cam ring in response to a supply of the working oil into the first control oil chamber;   a second control oil chamber configured to act a force in a direction in which the eccentricity quantity becomes large upon the cam ring in response to a supply of the working oil into the second control oil chamber;   a switching mechanism formed to enable a switching between a state in which the working oil from the second control oil chamber is exhausted and a state in which the working oil is introduced into the second control oil chamber; and   a control mechanism configured to take a state in which the working oil within the first control oil chamber is exhausted and another state in which the working oil whose pressure is decreased than a discharge pressure from the discharge section is introduced into the first control oil chamber and to perform a pressure regulation for the working oil while applying the pressure to the working oil within the first control oil chamber by introducing the working oil into the first control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the state in which the working oil is exhausted from the second control oil chamber, and to take a further another state in which the working oil whose pressure is decreased than the discharge pressure from the discharge section is introduced into the second control oil chamber and a still further another state in which an introduction of the working oil into the second control oil chamber via the switching mechanism is interrupted and the working oil within the second control oil chamber is exhausted and to perform the pressure regulation for the working oil while reducing the pressure to the working oil within the second control oil chamber by exhausting the working oil within the second control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the other state in which the working oil is introduced into the second control oil chamber, wherein the control mechanism is controlled by a hydraulic pressure of the working oil and a biasing force of a biasing member and the working oil is not introduced into a location of the control mechanism at which the biasing member is arranged.   
     
     
         18 . The variable capacity oil pump as claimed in  claim 17 , wherein the first and second control oil chambers are disposed on an outer peripheral side of the cam ring and are defined by a swing fulcrum installed on the outer peripheral side of the cam ring.