Hydraulic control system having accumulator

Abstract

A hydraulic control system for preventing shortage of lubricant and coolant during charging of an accumulator is disclosed. The hydraulic control system is comprised of: a hydraulic pump; an accumulator for storing fluid from the pump; and a constant delivery site which is connected to the pump in parallel with the accumulator, and which requires hydraulic fluid constantly during activation of the hydraulic pump. A pressure level of the fluid discharged from the pump is regulated to a level possible to be delivered to the accumulator, and the fluid resulting from the pressure regulation is delivered to the constant delivery site. Meanwhile, a pressure higher than that required by the constant delivery site is stored in the accumulator. The hydraulic control system is characterized by a fluid increasing means that delivers additional fluid to the constant delivery site together with the fluid resulting from said pressure regulation, when delivering the fluid discharged from the pump to the accumulator.

1 . A hydraulic control system, comprising:
 a hydraulic pump;   an accumulator that stores hydraulic fluid discharged from the hydraulic pump;   a constant delivery site connected to the hydraulic pump in parallel with the accumulator, that requires hydraulic fluid constantly during activation of the hydraulic pump;   wherein the hydraulic fluid resulting from regulating a pressure level of the hydraulic fluid discharged from the hydraulic pump to a level possible to be delivered to the accumulator side is delivered to the constant delivery site; and   wherein the hydraulic pressure higher than the pressure required by the constant delivery site is stored in the accumulator;   the hydraulic control system further comprising:   a fluid increasing means that delivers additional fluid to the constant delivery site together with the hydraulic fluid resulting from said pressure regulation, when delivering the hydraulic fluid discharged from the hydraulic pump to the accumulator.   
     
     
         2 . The hydraulic control system as claimed in  claim 1 , wherein the fluid increasing means comprises:
 a high pressure passage for delivering the hydraulic fluid discharged from the hydraulic pump to the accumulator; and   a flow volume increasing device that is activated by the hydraulic fluid delivered from the high pressure passage to increase a flow volume of the hydraulic fluid being delivered to the constant delivery site.   
     
     
         3 . The hydraulic control system as claimed in  claim 2 , further comprising:
 a constant supply passage for delivering the hydraulic fluid resulting from said pressure regulation to the constant delivery site; and   a bypass passage connecting the high pressure passage with the constant supply passage;
 wherein the flow volume increasing device includes a jet pump disposed on the bypass passage, that is adapted to introduce fluid therein from a reservoir by a negative pressure resulting from spraying the hydraulic fluid flowing through the bypass passage into the flow volume increasing device. 
   
     
     
         4 . The hydraulic control system as claimed in  claim 2 , further comprising:
 a shutoff device that blocks off the flow of the hydraulic fluid to the flow volume increasing device when the hydraulic fluid is not delivered from the hydraulic pump to the accumulator through the high pressure passage.   
     
     
         5 . The hydraulic control system as claimed in  claim 4 , wherein the shutoff device includes:
 a first on/off valve that is disposed on the high pressure passage between the hydraulic pump and a branching point of the bypass passage, and that is opened to deliver the hydraulic fluid to the accumulator; and   a second on/off valve that is disposed on the bypass passage between an outlet of the flow volume increasing device and the constant supply passage, and that is opened to deliver the hydraulic fluid to the constant supply passage.   
     
     
         6 . The hydraulic control system as claimed in  claim 5 ,
 wherein the first on/off valve includes a check valve that is adapted to be opened elastically when the pressure of the hydraulic fluid flowing toward the accumulator exceeds a predetermined opening level, and that is adapted to block the hydraulic fluid flowing backwardly from the accumulator.   
     
     
         7 . The hydraulic control system as claimed in  claim 5 ,
 wherein the second on/off valve includes a check valve that is opened by the hydraulic fluid delivered to the constant supply passage.   
     
     
         8 . The hydraulic control system as claimed in  claim 1 , further comprising:
 an engine that drives the hydraulic pump; and   an electric pump that is driven by a motor to discharge the hydraulic fluid;   wherein the fluid increasing means includes a switching valve that is switched to deliver the hydraulic fluid discharged from the electric pump to the constant delivery site when the hydraulic fluid is being delivered from the hydraulic pump to the accumulator.   
     
     
         9 . The hydraulic control system as claimed in  claim 8 ,
 wherein the switching valve includes a valve that provides communication between the electric pump and the constant delivery site when the hydraulic fluid discharged from the hydraulic pump is regulated to a pressure level possible to be delivered to the accumulator side, and that provides communication between the electric pump and the accumulator side when the hydraulic fluid discharged from the hydraulic pump is regulated to a pressure level lower than the level at which the hydraulic fluid is allowed to be delivered toward the accumulator side.   
     
     
         10 . The hydraulic control system as claimed in  claim 8 , further comprising:
 a deficiency calculation means that calculates a deficit flow quantity of the hydraulic fluid being delivered from the hydraulic pump to the constant delivery site when delivering the hydraulic fluid discharged from the hydraulic pump to the accumulator side; and   an electric pump control means that controls the electric pump based on the deficit flow quantity of the hydraulic fluid calculated by the deficiency calculation means.   
     
     
         11 . The hydraulic control system as claimed in  claim 10 ,
 wherein the electric pump includes an oil pump that is adapted to discharge the hydraulic fluid in accordance with a rotational speed thereof; and   the electric pump control means includes a means that controls a rotational speed of the electric pump or the motor in a manner such that the electric pump is allowed to discharge the hydraulic fluid in an amount to compensate for the deficiency of the hydraulic fluid calculated by the deficiency calculation means.   
     
     
         12 . The hydraulic control system as claimed in  claim 1 , further comprising:
 a fluid coupling having a lock-up clutch that is engaged and disengaged hydraulically; and   a control valve that creates a hydraulic pressure for controlling the lock-up clutch;   wherein the fluid increasing means comprises a flow volume increasing device that is driven by the hydraulic fluid delivered to the lock-up clutch to increase the flow volume of the hydraulic fluid being delivered to the constant delivery site.   
     
     
         13 . The hydraulic control system as claimed in  claim 12 ,
 wherein the flow volume increasing device includes a jet pump, that is disposed between a passage for delivering the hydraulic fluid to the lock-up clutch and the passage for delivering the hydraulic fluid to the constant delivery site, and that is adapted to introduce the fluid therein from a reservoir by a negative pressure resulting from spraying the hydraulic fluid being delivered to the lock-up clutch into the jet pump.   
     
     
         14 . The hydraulic control system as claimed in  claim 13 , further comprising:
 a switching valve, that is disposed before an inlet of the jet pump, and that is opened to allow the hydraulic fluid to be delivered to the jet pump when the pressure level of the hydraulic fluid being delivered to the accumulator side is high, and closed to block the flow of the hydraulic fluid toward the jet pump when the pressure level of the hydraulic fluid being delivered to the accumulator side is low.   
     
     
         15 . The hydraulic control system as claimed in  claim 1 , further comprising:
 a pressure regulator valve that regulates a hydraulic pressure established by the hydraulic pump; and   wherein the hydraulic fluid drained from the pressure regulator valve as a result of regulating the hydraulic pressure is delivered to the constant delivery site.   
     
     
         16 . The hydraulic control system as claimed in  claim 1 ,
 wherein the constant delivery site includes at least any one of a lubrication point and a cooling spot cooled by oil.   
     
     
         17 . The hydraulic control system as claimed in  claim 7 , further comprising:
 a pressure regulator valve that regulates a hydraulic pressure established by the hydraulic pump while outputting a signal pressure in accordance with a pressure regulating level;   wherein the hydraulic fluid drained from the pressure regulator valve as a result of regulating the hydraulic pressure is delivered to the constant delivery site; and   wherein the switching valve includes a valve that is switched by the signal pressure.   
     
     
         18 . The hydraulic control system as claimed in  claim 9 , further comprising:
 a deficiency calculation means that calculates a deficit flow quantity of the hydraulic fluid being delivered from the hydraulic pump to the constant delivery site when delivering the hydraulic fluid discharged from the hydraulic pump to the accumulator side; and   an electric pump control means that controls the electric pump based on the deficit flow quantity of the hydraulic fluid calculated by the deficiency calculation means.   
     
     
         19 . The hydraulic control system as claimed in  claim 18 ,
 wherein the electric pump includes an oil pump that is adapted to discharge the hydraulic fluid in accordance with a rotational speed thereof; and   the electric pump control means includes a means that controls a rotational speed of the electric pump or the motor in a manner such that the electric pump is allowed to discharge the hydraulic fluid in an amount to compensate for the deficiency of the hydraulic fluid calculated by the deficiency calculation means.   
     
     
         20 . The hydraulic control system as claimed in  claim 14 , further comprising:
 a pressure regulator valve that regulates a hydraulic pressure established by the hydraulic pump while outputting a signal pressure in accordance with a pressure regulating level;   wherein the hydraulic fluid drained from the pressure regulator valve as a result of regulating the hydraulic pressure is delivered to the constant delivery site; and   wherein the switching valve includes a valve that is switched by the signal pressure.