Hydraulic control system for vehicles

Patent metadata

Field	Value
Publication number	US-9989148-B2
Application number	US-201314778269-A
Country	US
Kind code	B2
Filing date	Jun 7, 2013
Priority date	Mar 21, 2013
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

A hydraulic control system for vehicles is provided. A switching valve ( 34 ) that is adapted to provide a communication between an electric oil pump ( 25 ) and a drain passage while inhibiting a delivery of the oil from the electric oil pump ( 25 ) to the control object ( 20 , C) when an output pressure of the mechanical oil pump ( 9 ) is higher than a predetermined level, and to provide a communication between the electric oil pump ( 25 ) and the control object ( 20 , C) through a predetermined oil passage when an output pressure of the mechanical oil pump ( 9 ) is lower than the predetermined level. The electric oil pump ( 25 ) discharges oil before establishing the communication between the electric oil pump ( 25 ) and the control object ( 20 , C) as a result of reduction in the output pressure of the mechanical oil pump ( 9 ) to be lower than the predetermined level.

First claim

The invention claimed is:

1. A hydraulic control system for vehicles, comprising:
a mechanical oil pump that is driven by a prime mover;
an electric oil pump that is driven by an output torque of an electric motor;
a control object that is controlled by an oil delivered from at least one of the mechanical oil pump and the electric oil pump; and
a switching valve that is adapted to provide a communication between the electric oil pump and a drain passage while inhibiting a delivery of the oil from the electric oil pump to the control object when an output pressure of the mechanical oil pump is higher than a predetermined level, and to provide a communication between the electric oil pump and the control object through a predetermined oil passage when an output pressure of the mechanical oil pump is lower than the predetermined level,
wherein the hydraulic control system is configured to discharge the oil from the electric oil pump before establishing the communication between the electric oil pump and the control object as a result of reduction in the output pressure of the mechanical oil pump to be lower than the predetermined level,
wherein the predetermined oil passage includes a first oil passage for delivering the oil delivered to the control object partially to a low pressure site where a required pressure is lower than that of the control object, and
wherein the switching valve is adapted to allow the oil discharged from the electric oil pump to flow toward the control object through the first oil passage while inhibiting a delivery of the oil to flow toward the low pressure site, when the output pressure of the mechanical oil pump falls below the predetermined level so that the communication between the electric oil pump and the control object through the first oil passage is established.

2. The hydraulic control system for vehicles as claimed in claim 1 , further comprising:
a regulator valve that regulates hydraulic pressure applied to the control object, and an output side thereof is connected to the regulator valve;
a first orifice that reduces a flow rate of the oil flowing from the first oil passage to the low pressure site; and
a second oil passage that is connected to the mechanical oil pump and the regulator valve, and that allows the oil to be delivered to the low pressure site when a speed of the prime mover exceeds a predetermined speed.

3. The hydraulic control system for vehicles as claimed in claim 1 , further comprising a second orifice that reduces a flow rate of the oil discharged from the electric oil pump being drained through the drain passage, when the output pressure of the mechanical oil pump is higher than the predetermined level.

4. The hydraulic control system for vehicles as claimed in claim 1 , wherein the predetermined level is higher than a maximum required pressure of the control object.

5. The hydraulic control system for vehicles as claimed in claim 1 , wherein the predetermined level is lower than a maximum pressure level to be established by the electric oil pump.

6. The hydraulic control system for vehicles as claimed in claim 1 , wherein the control object includes an engagement device that is brought into engagement when starting the vehicle.

7. The hydraulic control system for vehicles as claimed in claim 6 , further comprising a second check valve that is disposed on an oil passage connecting the electric oil pump to the switching valve to prevent back flow of the oil toward the electric oil pump.

8. The hydraulic control system for vehicles as claimed in claim 1 , wherein the control object includes a hydraulic actuator adapted to change a speed ratio of a transmission in accordance with hydraulic pressure applied thereto, and to reduce the speed ratio by discharging the oil therefrom.

9. The hydraulic control system for vehicles as claimed in claim 1 , further comprising:
a fluid coupling that transmits a torque hydraulically from the prime mover; and
a lockup clutch that is arranged in parallel to the fluid coupling to directly transmit the torque from the prime mover when brought into engagement;
wherein the control object includes a second linear solenoid valve adapted to control an engagement pressure of the lockup clutch in accordance with an electric current applied thereto.

10. The hydraulic control system for vehicles as claimed in claim 1 , wherein the switching valve is actuated in accordance with an applied signal pressure established by the mechanical oil pump.

11. The hydraulic control system for vehicles as claimed in claim 10 , wherein the switching valve includes a spool valve adapted to switch a connection among the first oil passage and a second oil passage depending on a balance between a load pushing a spool thereof based on the signal pressure and an elastic force counteracting said load.

12. The hydraulic control system for vehicles as claimed in claim 1 , wherein the switching valve is actuated in accordance with an applied signal pressure established by the electric oil pump.

13. The hydraulic control system for vehicles as claimed in claim 1 , wherein the hydraulic control system is configured to control an output pressure of the electric oil pump in accordance with a required pressure of the control object when the output pressure of the mechanical oil pump is lower than the predetermined level.

14. A hydraulic control system for vehicles, comprising:
a mechanical oil pump that is driven by a prime mover;
an electric oil pump that is driven by an output torque of an electric motor;
a control object that is controlled by an oil delivered from at least one of the mechanical oil pump and the electric oil pump;
a switching valve that is adapted to provide a communication between the electric oil pump and a drain passage while inhibiting a delivery of the oil from the electric oil pump to the control object when an output pressure of the mechanical oil pump is higher than a predetermined level, and to provide a communication between the electric oil pump and the control object through a predetermined oil passage when an output pressure of the mechanical oil pump is lower than the predetermined level; and
a control valve that controls hydraulic pressure applied to the control object based on an initial pressure established by the oil discharged from the mechanical oil pump,
wherein the hydraulic control system is configured to discharge the oil from the electric oil pump before establishing the communication between the electric oil pump and the control object as a result of reduction in the output pressure of the mechanical oil pump to be lower than the predetermined level, and
wherein the control valve is adapted to be opened to lower the hydraulic pressure applied to the control object when the hydraulic pressure applied to the control object is higher than the required pressure thereof during delivering the oil from the electric oil pump to the control object.

15. The hydraulic control system for vehicles as claimed in claim 14 , further comprising:
a first check valve that is disposed on an oil passage connecting the mechanical oil pump to the control valve to prevent back flow of the oil toward the mechanical oil pump;
wherein the switching valve is adapted to establish a communication between an oil passage of an input side of the first check valve and an oil passage of an output side of the first check valve when the output pressure of the mechanical oil pump is higher than the predetermined level.

16. The hydraulic control system for vehicles as claimed in claim 14 ,
wherein the switching valve compr

Assignees

• Toyota Motor Co Ltd

Inventors

• Ogata Yusuke
• Nakada Hirofumi

Classifications

• Y10T137/86163

  Parallel · CPC title

• F16H61/143

  using electric control means · CPC title

• F16H61/0021

  Generation or control of line pressure · CPC title

• F16H61/0267 Primary

  Layout of hydraulic control circuits, e.g. arrangement of valves · CPC title

• B60K6/48

  Parallel type · CPC title