Differential unit with means for mixing air into the hydraulic actuator

• US 5,709,627 A
• Filed: 03/27/1996
• Issued: 01/20/1998
• Est. Priority Date: 03/28/1995
• Status: Expired due to Fees

• Current Assignee: Tochigi Fuji Sangyo Kabushiki Kaisha (Melrose Industries Plc)
• Original Assignee: Tochigi Fuji Sangyo Kabushiki Kaisha (Melrose Industries Plc)
• Inventors: Teraoka, Masao
• Primary Examiner(s): TA, KHOI QUANG
• Application Number:
  US08/623,325
• Time in Patent Office: 664 Days
• Field of Search: 475/86, 475/88, 475/84, 475/116, 475/117, 475/231, 475/233, 475/237, 475/238, 477/35, 184/6.23, 184/6.4
• US Class Current: 475/86
• CPC Class Codes: B60K 23/04 for differential gearing
• CPC Class Codes: F16H 2048/204 Control of arrangements for suppressing differential actions
• CPC Class Codes: F16H 2048/205 using the steering as a control parameter
• CPC Class Codes: F16H 2200/2071 using three freewheel mechanism
• CPC Class Codes: F16H 48/08 comprising bevel gears
• CPC Class Codes: F16H 48/22 using friction clutches or brakes
• CPC Class Codes: F16H 48/27 using internally-actuatable fluid pressure, e.g. internal pump types
• CPC Class Codes: F16H 48/30 using externally-actuatable means
• CPC Class Codes: F16H 48/32 using fluid pressure actuators
• CPC Class Codes: F16H 48/40 characterised by features of the rotating cases

Abstract

A differential unit having a speed-sensitive-type differential limiting function is capable of moderating the differential limiting force to maintain the controllability and stability of a vehicle. The differential unit according to the present invention includes a differential case to be rotated by drive force of an engine, a differential mechanism for distributing rotations of the differential case to a pair of output shafts, a frictional clutch for limiting the differential of the differential mechanism, a hydraulic actuator for clutching the frictional clutch, an oil pump which receives differential torque of the differential mechanism so as to be driven to operate the hydraulic actuator, control valves for introducing air to the oil suction portion of the oil pump, and a controller for opening or closing the control valve to correspond to a condition under which a vehicle is driven.

Claims

1. A differential unit comprising:

a differential case to be rotated by drive force of an engine;

a differential mechanism for distributing rotations of said differential case to a pair of output shares;

a frictional clutch for limiting the differential of said differential mechanism;

a hydraulic actuator for clutching said frictional clutch;

an oil pump which receives differential torque of said differential mechanism so as to be driven to operate said hydraulic actuator;

a control valve for introducing air to an oil suction portion of said oil pump; and

a controller for opening or closing said control valve to correspond to a condition under which a vehicle is driven.

2. A differential unit according to claim 1, wherein said control valve is able to adjust the quantity of air to be introduced into the oil suction portion of said oil pump.

3. A differential unit according to claim 1, wherein said differential mechanism is a bevel-gear-type differential mechanism having a pinion gear rotatively supported at a position adjacent to said differential case and a pair of output side-gears engaged to said pinion gear,

said frictional clutch is a multiple disc clutch disposed between said side gear and said differential case,

said oil pump is disposed between said side gear and said differential case, and

said hydraulic actuator is disposed between said side gear and said oil pump.

5. A differential unit according to claim 1, further comprising oil-temperature detection means for detecting the temperature of oil which passes through said oil pump, wherein

said controller opens or closes said control valve in accordance with the temperature detected by said oil-temperature detection means.

4. A differential unit comprising:

a differential case to be rotated by the drive force of an engine;

a differential mechanism for distributing rotations of said differential case to a pair of output shafts;

a frictional clutch for limiting the differential of said differential mechanism;

a hydraulic actuator for clutching said frictional clutch;

an oil pump which receives differential torque of said differential mechanism so as to be driven to operate said hydraulic actuator; and

an adjustment valve which receives pilot pressure from said oil pump to be opened in a case where the discharge pressure from said oil pump exceeds a predetermined level so as to introduce air into the oil suction portion of said oil pump.