Pressurized fluid supply system for automatic power transmission for automotive vehicle

• US 5,222,418 A
• Filed: 07/19/1991
• Issued: 06/29/1993
• Est. Priority Date: 07/21/1990
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Murota, Kazuya
• Primary Examiner(s): Braun, Leslie A.
• Assistant Examiner(s): HENN, DAVID
• Application Number:
  US07/733,123
• Time in Patent Office: 711 Days
• Field of Search: 74/467, 74/867, 475/159, 184/6.12
• US Class Current: 475/159
• CPC Class Codes: F16H 2061/0037 characterised by controlled fluid supply to lubrication circuits of the gearing see also lubrication control F16H57/0446
• CPC Class Codes: F16H 57/0434 relating to lubrication supply, e.g. pumps arrangement of pumps F16H57/0441; Pressure control grooves with pumping effect for supplying lubricant F16H57/0428; generation and variation of line pressure for transmission control F16H61/0021
• CPC Class Codes: F16H 59/72 dependent on oil characteristics, e.g. temperature, viscosity
• CPC Class Codes: F16H 61/0025 Supply of control fluid; Pumps therefore
• CPC Class Codes: Y10T 74/19991 Lubrication

Abstract

A novel hydraulic system for an automotive automatic power transmission improves efficiency of working fluid supply for controlling transmission operation and for lubricating transmission components. The hydraulic system employs independently fabricated lubrication circuit for lubricating transmission components and a hydraulic control circuit for controlling operation of transmission components. The hydraulic system employs a first fluid pump connected to the hydraulic control circuit for supplying working fluid thereto, and a second fluid pump connected to the lubrication circuit for supplying working fluid thereto, and operative independently of the first fluid pump.

Claims

1. A hydraulic system for an automatic power transmission including a torque converter and a transmission mechanism, comprising:

a lubrication circuit for lubricating components of said transmission mechanism;

a hydraulic control circuit for controlling operation of said automatic transmission;

first pressurized fluid source means for supplying pressurized fluid to said hydraulic control circuit;

second pressurized fluid source means, driven independently of said first pressurized fluid source means, for supplying pressurized fluid to said lubrication circuit; and

vale means for normally allowing independent supply of fluid pressure from said first and second fluid pressure source means to an associated lubrication circuit and a hydraulic control circuit, respectively, said valve means being responsive to one of said first and second fluid pressure source means when it assumes a state in which it does not supply pressurized fluid to the associated circuit, for establishing fluid communication between the other of said first and second fluid source means and that circuit which is associated with said one of said first and second fluid pressure source means.

2. A hydraulic system for an automatic power transmission including a torque converter and a transmission mechanism, comprising:

a lubrication circuit for lubricating components of said transmission mechanism;

a hydraulic control circuit for controlling operation of said automatic transmission;

first pressurized fluid source means for supplying pressurized fluid to said hydraulic control circuit;

second pressurized fluid source means, operative independently of said first pressurized fluid source means, for supplying pressurized fluid to said lubrication circuit; and

flow control means, provided in a fluid path for recirculating working fluid through said hydraulic control circuit to said torque converter, for adjusting the flow rate of the fluid recirculating to said torque converter depending upon the load of said torque converter.

3. The hydraulic system as set forth in claim 2, wherein said flow control means is a temperature-responsive flow control means for increasing the flow rate of the fluid flowing therethrough, in accordance with the increase in fluid temperature.

4. A hydraulic system for an automatic power transmission including a torque converter and a transmission mechanism, comprising:

a lubrication circuit for lubricating components of said transmission mechanism;

a hydraulic control circuit for controlling operation of said automatic transmission;

first pressurized fluid source means for supplying pressurized fluid to said hydraulic control circuit; and

second pressurized fluid source means driven independently of said first pressurized fluid source means, for supplying pressurized fluid to said lubrication circuit;

wherein one of said first and second pressurized fluid source means is associated with an input shaft of said automatic transmission to be driven by driving torque transmitted therethrough, and the other of said first and second pressurized fluid source means is associated with an output shaft of said automatic transmission to be driven by driving torque transmitted therethrough; and

valve means, adapted to cooperate with said the other of said first and second pressurized fluid source means, for switching the fluid flow direction across said the other pressurized fluid source means when it is driven in a reverse direction.

5. A hydraulic circuit system for an automatic power transmission unit for an automotive vehicle, said automatic power transmission unit incorporating a torque converter, a transmission casing, and a power transmission mechanism accommodated within said transmission casing and including a gear train shiftable for establishing one of a plurality of transmission speed ratios between input and output shafts of the power transmission mechanism, said hydraulic circuit system comprising:

a control circuit for supplying a control pressure to said power transmission mechanism in order to establish a desired one of said transmission speed ratios;

a lubrication circuit for supplying lubricating fluid for lubrication of said gear train, said lubrication circuit being fabricated independently of said control circuit;

first pressurized fluid source means, mounted on said transmission casing and driven by driving torque transmitted across said automatic transmission, for supplying said control pressure to said control circuit; and

second pressurized fluid source means, mounted on said transmission casing and driven by driving torque transmitted across said automatic transmission and driven independently of said first fluid source means, for supplying said lubricating fluid for said lubrication circuit;

wherein one of said first and second pressurized fluid source means is coupled with said input shaft to be driven by the input torque transmitted therethrough, and the other of said first and second pressurized fluid source means is coupled with said output shaft to be driven by the output torque transmitted therethrough, and

wherein said first and second pressurized fluid source means are connected to a common working fluid reservoir means, and said the other of said first and second fluid source means is connected to said common working fluid reservoir means via a pair of paths, one of which is adapted to suck the working fluid therein and the other of which is adapted to recirculate part of the working fluid to a suction side of said the other of said first and second fluid source means, said pair of paths being communicated across a valve means for preventing surge flow of working fluid thereacross, and said pair of paths switching functions of sucking and recirculating the working fluid depending upon the driving direction of said output shaft.

6. The hydraulic circuit system as set forth in claim 5, further comprising a lubricating fluid supply switching valve, disposed between said lubrication circuit and a return path for recirculating control pressure path through said control circuit to said working fluid reservoir means, said lubricating fluid supply switching valve being responsive to the pressure level of said lubricating fluid supplied from said second pressurized fluid source means, for blocking fluid communication therebetween while said lubricating fluid pressure level is higher than a predetermined pressure level, and for establishing fluid communication therebetween while the lubricating fluid pressure level is lower than said predetermined pressure level.

7. The hydraulic circuit system as set forth in claim 6, further comprising fail-safe circuit means for establishing communication between said second pressurized fluid source means and said control circuit, said fail-safe circuit means being normally placed in an inactive state for blocking fluid communication between said second pressurized fluid source means and said control circuit and responsive to failure of one of said first and second pressurized fluid source means for establishing fluid communication between said control circuit and said pressurized fluid source means.

8. The hydraulic circuit system as set forth in claim 7, wherein said automatic power transmission is coupled with a differential gear unit for forming an automatic transaxle, said second pressurized fluid source means comprising an gear pump formed by an output gear which is driven by said output shaft, and an idler gear which is mounted on a counter shaft of said differential gear unit.

9. A hydraulic circuit system for an automatic power transmission unit for an automotive vehicle, said automatic power transmission unit incorporating a torque converter, a transmission casing, and a power transmission mechanism accommodated within said transmission casing and including a gear train shiftable for establishing one of a plurality of transmission speed ratios between input and output shafts of the power transmission mechanism, said hydraulic circuit system comprising:

a control circuit for supplying a control pressure to said power transmission mechanism in order to establish a desired one of said transmission speed ratios;

a lubrication circuit for supplying lubricating fluid for lubrication of said gear train, said lubrication circuit being fabricated independently of said control circuit;

first pressurized fluid source means, mounted on said transmission casing and driven by driving torque transmitted across said automatic transmission, for supplying said control pressure to said control circuit;

second pressurized fluid source means, mounted on said transmission casing and driven by driving torque transmitted across said automatic transmission and driven independently of said first fluid source means, for supplying said lubricating fluid for said lubrication circuit; and

fail-safe circuit means for establishing at least one of communications between said first pressurized fluid source means and said lubrication circuit, and between said second pressurized fluid source means and said control circuit, said fail-safe circuit means being normally placed in an inactive state and responsive to failure of one of said first and second pressurized fluid source means, for establishing fluid communication between the normally operating pressurized fluid source means and one of said lubrication circuit and said control circuit associated with the faulty pressurized fluid source means.

10. A hydraulic circuit system for an automatic power transmission unit for an automotive vehicle, said automatic power transmission unit incorporating a torque converter, a transmission casing and a power transmission mechanism accommodated within said transmission casing and including a gear train shiftable for establishing one of a plurality of transmission speed ratios between input and output shafts of the power transmission mechanism, said hydraulic circuit system comprising:

a control circuit for supplying a control pressure to said power transmission mechanism in order to establish a desired one of said transmission speed ratios;

a lubrication circuit for supplying lubricating fluid for lubrication of said gear train, said lubrication circuit being fabricated independently of said control circuit;

first pressurized fluid source means, mounted on said transmission casing and driven by driving torque transmitted across said automatic transmission, for supplying said control pressure to said control circuit;

second pressurized fluid source means, mounted on said transmission casing and driven by driving torque transmitted across said automatic transmission and operable independently of said first fluid source means, for supplying said lubricating fluid for said lubrication circuit; and

flow control means, disposed in a fluid path connecting said control circuit and a working fluid source means, for recirculating the working fluid from said control circuit to said working fluid source means, said flow control means being adapted to adjust the fluid flow rate recirculating to said working fluid source depending upon the operational load on said torque converter, utilizing working fluid in said fluid source means for operation.

11. The hydraulic circuit system as set forth in claim 10, wherein said flow control means includes means for adjusting the fluid recirculation rate by detecting the operational load on said torque converter.

12. The hydraulic circuit system as set forth in claim 11, wherein said adjusting means is adapted to detect fluid temperature as a parameter representative of the operational load on said torque converter.

13. A hydraulic system for an automatic power transmission with a torque converter, comprising:

first circuit means, connected to a first load, for supplying a first fluid pressure to said first load so that said first load performs a predetermined first function for the automatic power transmission;

second circuit means, connected to a second load of the automatic power transmission, for supplying a second fluid pressure to said second load so that said second load performs a predetermined second function for said automatic power transmission;

first pressurized fluid source means for supplying pressurized fluid to said first circuit means; and

second pressurized fluid source means, operative independently of said first pressurized fluid source, for supplying pressurized fluid to said second circuit means, said second pressurized fluid source means being operative in a first mode for supplying fluid pressure in a first direction, and a second mode for supplying fluid pressure in a second direction opposite to said first direction or for stopping supply of fluid pressure; and

means, responsive to said second pressurized fluid source means operating in said first mode, for blocking fluid communication between said first and second circuit means so that pressurized fluid is supplied to said second circuit means from said second pressurized fluid source means, and responsive to said second pressurized fluid source means operating in said second mode, for establishing fluid communication between said first circuit means and said second circuit means in order to supply fluid pressure in said first circuit means to said second circuit means in order to supply fluid pressure in said first circuit means to said second circuit means.