Hydraulic control unit

Patent metadata

Field	Value
Publication number	US-9523425-B2
Application number	US-201214405199-A
Country	US
Kind code	B2
Filing date	Jun 8, 2012
Priority date	Jun 8, 2012
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

A hydraulic control unit is provided. A valve is comprised of a piston having a valve element, a cylinder holding the piston while allowing to reciprocate axially, a positive pressure chamber formed on one side of the piston to which pressure to open the valve is applied, a back pressure chamber formed on the other side of the piston to which the pressure to close the valve is applied, and a connection passage for differentiating pressures in the positive pressure chamber and the back pressure chamber. A pilot valve selectively connects the back pressure chamber with a site where the pressure is lower than that of the back pressure chamber. Hydraulic pressure lower than that applied to positive pressure chamber is applied to a low pressure section. The hydraulic control unit comprises a means to deliver the fluid from the low pressure section to the back pressure chamber if an opening motion of the valve is slower than a predetermined reference value, by opening the pilot valve to connect the back pressure chamber with the low pressure section.

First claim

The invention claimed is:

1. A hydraulic control unit, comprising:
a valve comprising a piston integrated with a valve element, a cylinder holding the piston while allowing to reciprocate axially, a positive pressure chamber which is formed on one side of the piston and to which hydraulic pressure to open the valve is applied, a back pressure chamber which is formed on the other side of the piston and to which the hydraulic pressure to close the valve is applied, and a connection passage having a function to differentiate hydraulic pressures in the positive pressure chamber and the back pressure chamber;
a pilot valve that selectively connects the back pressure chamber with a site where the pressure is lower than that of the back pressure chamber;
a low pressure section to which the hydraulic pressure lower than that applied to positive pressure chamber is applied; and
a controller configured to deliver hydraulic fluid from the low pressure section to the back pressure chamber through a bypass passage if an opening motion of the valve is slower than a predetermined reference value, by opening the pilot valve to allow the hydraulic fluid to be drained from the back pressure chamber to the site where the pressure is lower than that of the back pressure chamber.

2. The hydraulic control unit as claimed in claim 1 , further comprising:
a prime mover; and
wherein said controller is further configured to deliver the hydraulic fluid from the low pressure section to the back pressure chamber through the bypass passage if the prime mover is started, by opening the pilot valve to allow the hydraulic fluid to be drained from the back pressure chamber to the site where the pressure is lower than that of the back pressure chamber.

3. The hydraulic control unit as claimed in claim 1 ,
wherein the pilot valve is adapted to selectively connect a pilot port of the back pressure chamber to the site where the pressure is lower;
wherein
the bypass passage directly connects the back pressure chamber to the low pressure section, and a cross-sectional area thereof is larger than that of a portion of the connection passage to differentiate the hydraulic pressures,
wherein the hydraulic control unit further comprises a switching valve that is disposed on the bypass passage to selectively connect the bypass passage with the low pressure section; and

wherein said controller is further configured to connect the bypass passage with the low pressure section to deliver the hydraulic fluid from the low pressure section to the back pressure chamber if the opening motion of the valve is slower than the predetermined reference value, by opening pilot valve while operating the switching valve to allow the hydraulic fluid to be drained from the back pressure chamber to the site where the pressure is lower than that of the back pressure chamber.

4. The hydraulic control unit as claimed in claim 1 ,
wherein the positive pressure chamber is comprised of an input port to which the fluid to open the valve is delivered, and an output port which is closed by the valve element; and
wherein the switching valve is disposed between a hydraulic chamber of a pulley of a belt-driven continuously variable transmission and a hydraulic source, and the output port is connected with the hydraulic chamber.

5. The hydraulic control unit as claimed in claim 2 ,
wherein the pilot valve is adapted to selectively connect a pilot port of the back pressure chamber to the site where the pressure is lower;
wherein
the bypass passage directly connects the back pressure chamber to the low pressure section, and a cross-sectional area thereof is larger than that of a portion of the connection passage to differentiate the hydraulic pressures,
wherein the hydraulic control unit further comprises a switching valve that is disposed on the bypass passage to selectively connect the bypass passage with the low pressure section; and

wherein said controller is further configured to connect the bypass passage with the low pressure section to deliver the hydraulic fluid from the low pressure section to the back pressure chamber if the opening motion of the valve is slower than the predetermined reference value, by opening pilot valve while operating the switching valve to allow the hydraulic fluid to be drained from the back pressure chamber to the site where the pressure is lower than that of the back pressure chamber.

6. The hydraulic control unit as claimed in claim 2 ,
wherein the positive pressure chamber is comprised of an input port to which the fluid to open the valve is delivered, and an output port which is closed by the valve element; and
wherein the switching valve is disposed between a hydraulic chamber of a pulley of a belt-driven continuously variable transmission and a hydraulic source, and the output port is connected with the hydraulic chamber.

7. The hydraulic control unit as claimed in claim 3 ,
wherein the positive pressure chamber is comprised of an input port to which the fluid to open the valve is delivered, and an output port which is closed by the valve element; and
wherein the switching valve is disposed between a hydraulic chamber of a pulley of a belt-driven continuously variable transmission and a hydraulic source, and the output port is connected with the hydraulic chamber.

8. The hydraulic control unit as claimed in claim 5 ,
wherein the positive pressure chamber is comprised of an input port to which the fluid to open the valve is delivered, and an output port which is closed by the valve element; and
wherein the switching valve is disposed between a hydraulic chamber of a pulley of a belt-driven continuously variable transmission and a hydraulic source, and the output port is connected with the hydraulic chamber.

Assignees

• Inagaki Takafumi
• Hattori Yuji
• Inagawa Tomokazu
• Kimura Kenta
• Nagasato Yu
• Toyota Motor Co Ltd

Inventors

• Inagaki Takafumi
• Hattori Yuji
• Inagawa Tomokazu
• Kimura Kenta
• Nagasato Yu

Classifications

• B60Y2400/72

  Continous variable transmissions [CVT] · CPC title

• Y10T137/7761

  Electrically actuated valve · CPC title

• F16H61/66272

  characterised by means for controlling the torque transmitting capability of the gearing · CPC title

• F16H2061/145

  for controlling slip, e.g. approaching target slip value · CPC title

• F16H61/143

  using electric control means · CPC title