Variable-flow rate oil pump

Abstract

A variable-flow rate oil pump includes: a main oil pump; a subsidiary oil pump; a control valve provided with a spool valve body; a main discharge oil passage; a subsidiary discharge oil passage merging with the main discharge oil passage; a main relief oil passage branching from the main discharge oil passage; a subsidiary relief oil passage branching from the subsidiary discharge oil passage; and a check valve permitting a flow only in one direction from the upstream side to the downstream side of the subsidiary discharge oil passage. The control valve is positioned at respective intermediate points of the main relief oil passage and the subsidiary relief oil passage, and the control valve is positioned on the upstream side of the check valve in the subsidiary discharge oil passage, and an engine speed at which the subsidiary discharge oil passage.

1 . A variable-flow rate oil pump, comprising: a main oil pump; a subsidiary oil pump; a control valve provided with a spool valve body; a main discharge oil passage extending from the main oil pump; a subsidiary discharge oil passage extending from the subsidiary oil pump and merging with the main discharge oil passage; a main relief oil passage branching from the main discharge oil passage; a subsidiary relief oil passage branching from the subsidiary discharge oil passage; and a check valve permitting a flow only in one direction from an upstream side to a downstream side of the subsidiary discharge oil passage, wherein
 the control valve is positioned at respectively intermediate points of the main relief oil passage and the subsidiary relief oil passage; the control valve is positioned on the upstream side of the check valve in the subsidiary discharge oil passage; and an engine speed at which the subsidiary discharge oil passage is shut off by the check valve is set to be lower than an engine speed at which the subsidiary discharge oil passage is shut off by the spool valve body.   
     
     
         2 . The variable-flow rate oil pump according to  claim 1 , wherein an engine speed at which oil is relieved from the subsidiary relief oil passage by movement of the spool valve body is set to be lower than the engine speed at which the subsidiary discharge oil passage is shut off by the check valve. 
     
     
         3 . A variable-flow rate oil pump, comprising: a main oil pump; a subsidiary oil pump; a control valve provided with a spool valve body; a main discharge oil passage extending from the main oil pump; a subsidiary discharge oil passage extending from the subsidiary oil pump and merging with the main discharge oil passage; a main relief oil passage branching from the main discharge oil passage; a subsidiary relief oil passage branching from the subsidiary discharge oil passage; and a check valve permitting a flow only in one direction from an upstream side to a downstream side of the subsidiary discharge oil passage, wherein
 the control valve is positioned at respective intermediate points of the main relief oil passage and the subsidiary relief oil passage; the control valve is positioned on the upstream side of the check valve in the subsidiary discharge oil passage; the subsidiary discharge oil passage is shut off by the check valve before the subsidiary discharge oil passage is shut off due to movement of the spool valve body to the rear side; and relief of oil in the subsidiary relief oil passage is performed before the subsidiary discharge oil passage is shut off by the check valve.   
     
     
         4 . The variable-flow rate oil pump according to  claim 1 , wherein a main relief inflow port, a main relief expulsion port, a subsidiary inflow port, a subsidiary outflow port, a subsidiary relief inflow port, and a subsidiary relief expulsion port are provided from the front side in a valve chamber of the control valve; the subsidiary inflow port is provided at the same position as the subsidiary outflow port in the axial direction; the subsidiary relief inflow port is provided at the same position as the subsidiary relief expulsion port in the axial direction; a small-diameter valve chamber is provided at the front end of the valve chamber; in the spool valve body, a pressure receiving valve section, a first large-diameter valve section, a second large-diameter valve section and a third large-diameter valve section are formed successively from the front side to the rear side in the axial direction; the first large-diameter valve section shuts off and enables communication between the main relief inflow port and the main relief expulsion port; the third large-diameter valve section is configured so as to shut off and enable communication between the subsidiary relief inflow port and the subsidiary relief expulsion port; the pressure receiving valve section is inserted into the small-diameter valve chamber, and an operation outflow/inflow port is formed at the front end of the small-diameter valve chamber; the operation outflow/inflow port communicates with an operating oil passage that branches from the main relief oil passage; an operating valve and an expulsion oil passage are provided at an intermediate point of the operating oil passage; and the operating valve is configured so as to switch between either one of communication between the operating oil passage and the main relief oil passage and communication between the operating oil passage and the expulsion oil passage. 
     
     
         5 . The variable-flow rate oil pump according to  claim 4 , wherein a length in the axial direction of the first large-diameter valve section of the spool valve body is smaller than a maximum interval in the axial direction between the main relief expulsion port and the subsidiary outflow port. 
     
     
         6 . The variable-flow rate oil pump according to  claim 4 , wherein a length in the axial direction of the first large-diameter valve section of the spool valve body is equal to or greater than a maximum interval in the axial direction between the main relief expulsion port and the subsidiary outflow port. 
     
     
         7 . The variable-flow rate oil pump according to  claim 3 , wherein a main relief inflow port, a main relief expulsion port, a subsidiary inflow port, a subsidiary outflow port, a subsidiary relief inflow port, and a subsidiary relief expulsion port are provided from the front side in a valve chamber of the control valve; the subsidiary inflow port is provided at the same position as the subsidiary outflow port in the axial direction; the subsidiary relief inflow port is provided at the same position as the subsidiary relief expulsion port in the axial direction; a small-diameter valve chamber is provided at the front end of the valve chamber;
 in the spool valve body, a pressure receiving valve section, a first large-diameter valve section, a second large-diameter valve section and a third large-diameter valve section are formed successively from the front side to the rear side in the axial direction; the first large-diameter valve section shuts off and enables communication between the main relief inflow port and the main relief expulsion port; the third large-diameter valve section is configured so as to shut off and enable communication between the subsidiary relief inflow port and the subsidiary relief expulsion port; the pressure receiving valve section is inserted into the small-diameter valve chamber, and an operation outflow/inflow port is formed at the front end of the small-diameter valve chamber; the operation outflow/inflow port communicates with an operating oil passage that branches from the main relief oil passage; an operating valve and an expulsion oil passage are provided at an intermediate point of the operating oil passage; and the operating valve is configured so as to switch between either one of communication between the operating oil passage and the main relief oil passage and communication between the operating oil passage and the expulsion oil passage.   
     
     
         8 . The variable-flow rate oil pump according to  claim 7 , wherein a length in the axial direction of the first large-diameter valve section of the spool valve body is smaller than a maximum interval in the axial direction between the main relief expulsion port and the subsidiary outflow port. 
     
     
         9 . The variable-flow rate oil pump according to  claim 7 , wherein a length in the axial direction of the first large-diameter valve section of the spool valve body is equal to or greater than a maximum interval in the axial direction between the main relief expulsion port and the subsidiary outflow port.