Apparatus for controlling hydraulic pressure for clutch

• US 5,168,973 A
• Filed: 04/29/1991
• Issued: 12/08/1992
• Est. Priority Date: 03/25/1987
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Komatsu Seisakusho (Komatsu Ltd.)
• Original Assignee: Kabushiki Kaisha Komatsu Seisakusho (Komatsu Ltd.)
• Inventors: Sato, Takayuki, Asayama, Yoshio, Tsubota, Makio, Okura, Yasunori
• Primary Examiner(s): LORENCE, RICHARD M
• Application Number:
  US07/693,306
• Time in Patent Office: 589 Days
• Field of Search: 192/85 R, 192/109 F, 192/30 W, 192/87.1, 192/87.11, 137/486, 137/625.65, 91/433, 91/459
• US Class Current: 192/85.63
• CPC Class Codes: F16D 2048/0275 Two valves arranged in parallel, e.g. one for coarse and the other for fine control during supplying or draining fluid from the actuation cylinder
• CPC Class Codes: F16D 2500/1026 Hydraulic
• CPC Class Codes: F16D 2500/1112 Heavy vehicle
• CPC Class Codes: F16D 2500/3024 Pressure
• CPC Class Codes: F16D 2500/3025 Fluid flow
• CPC Class Codes: F16D 2500/3026 Stroke
• CPC Class Codes: F16D 2500/5014 Filling the actuator cylinder with fluid
• CPC Class Codes: F16D 2500/7042 Voltage
• CPC Class Codes: F16D 2500/70424 Outputting a clutch engaged-disengaged signal
• CPC Class Codes: F16D 48/062 of a clutch system with a plurality of fluid actuated clutches
• CPC Class Codes: F16D 48/066 Control of fluid pressure, e.g. using an accumulator F16D48/062, F16D48/068 take precedence
• CPC Class Codes: F16H 2059/6807 Status of gear-change operation, e.g. clutch fully engaged
• CPC Class Codes: F16H 2061/0209 with independent solenoid valves modulating the pressure individually for each clutch or brake
• CPC Class Codes: F16H 2061/0288 Relay valve, e.g. valve arranged between shift valve and servo
• CPC Class Codes: F16H 2061/062 for controlling filling of clutches or brake servos, e.g. fill time, fill level or pressure during filling
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: Y10T 137/7759 Responsive to change in rate of fluid flow
• CPC Class Codes: Y10T 137/86622 Motor-operated

Abstract

The present invention provides an apparatus for controlling a hydraulic pressure usable for a clutch wherein the appratus is employed for a transmission mounted on a construction machine or the like in such a manner that it is provided separately for a plurality of clutches 1 and it is controlled individually. The apparatus includes a first valve 3 for allowing a large amount of hydraulic oil to flow in the clutch and a second valve 4 for electronically controlling a clutch pressure so that the termination of filling and the clutch pressure are detected by a simple structural arrangement on the basis of a displacement of a spool 21 for the first valve 3 and a separately disposed piston. In addition, appearing of an overshoot pressure on the termination of filling is prevented by providing a difference in pressue receiving areas on the spool 21 for the first valve.

Claims

1. An apparatus for controlling hydraulic pressure adapted for use with a clutch comprising:

(a) a plurality of clutch pressure control valves corresponding to a plurality of piston cylinders of a plurality of speed-changing clutches, each clutch pressure control valve including;

a pressure control valve having a first spool provided with a solenoid on one end thereof and provided with a first spring on the other end thereof, said pressure control valve switching over an output port thereof to one of a drain port and a pump port connected to a pump in accordance with an instruction current applied to said solenoid and variably changing hydraulic pressure of said output port;

a flow rate detecting valve having a second spool provided on one end thereof with a second spring and an orifice for supplying oil flow through an input port leading to said output port of said pressure control valve and said pump port to a clutch port leading to said piston cylinder of said speed-changing clutch, said one end of said second spool being effected by hydraulic pressure of said clutch port, the other end of said second spool being effected by hydraulic pressure of said input port, said flow rate detecting valve, when opened by a pressure differential across said orifice, effecting hydraulic pressure of said pump port leading to said input port to act directly on said clutch port and, when the oil is filled into said piston cylinder of said speed-changing clutch, closing said pump port and said clutch port; and

(b) control means for controlling, at the time of speed changing, one of said plurality of piston cylinders of said speed-changing clutches connected with one of said plurality of pressure control valves required for said speed change by outputting said instruction current to said solenoid for said required pressure control valve.

2. The apparatus as claimed in claim 1 further including a plurality of filling detecting means corresponding to said plurality of piston cylinders of said speed-changing clutches, each adapted for detecting return of said second spool of said flow rate detecting valve to an initial position after having been displaced towards a direction to contract said second spring to thereby detect the completion of filling of the oil to said speed-changing clutch connected to said flow rate detecting valve having said second spool which has been displaced and detected its return to said initial position, and wherein said control means receives detection signals from said plurality of filling detecting means and detects on the basis of said detection signals the completion of filling of the oil to said piston cylinder of said speed-changing clutch connected to said flow rate detecting valve having said second spool which has been displaced and detected its return to said initial position.

3. The apparatus as claimed in claim 2, wherein said filling detecting means comprises a piston member, provided on the side where said second spring of said second spool is disposed, and detecting means for detecting displacement of said piston member so as to detect the completion of filling of the oil to said speed-changing clutch connected to said flow rate detecting valve having said second spool which has been displaced and detected its return to said initial position.

4. The apparatus as claimed in claim 3, wherein said detecting means comprises a member disposed at a position opposite to said one end of said second spool on which said second spring is disposed, and contact and noncontact detecting means for detecting contacting of said piston member with said member and parting of the former away from the latter.

5. The apparatus as claimed in claim 4, wherein said member comprises an electrically conductive housing cover disposed on a valve housing enclosing said pressure control valve and said flow rate detecting valve with an electrical insulating member interposed therebetween, and wherein said contact and noncontact detecting means is such that contacting of said piston member with said member and parting of the former away from the latter are represented in the form of an electric ON or OFF signal.

6. The apparatus as claimed in claim 5, wherein said contact and noncontact detecting means comprises voltage apply means for applying a predetermined intensity of voltage to said housing cover and voltage detecting means for detecting a voltage appearing on said housing cover when said piston member comes in contact with said housing cover and the former is parted away from the latter.

7. The apparatus as claimed in claim 2, wherein said filling detecting means comprises an electromagnetic pick-up disposed on said one end of said second spool of said flow rate detecting valve and outputs a voltage change signal corresponding to the displacement of said second spool of said flow rate detecting valve.

8. The apparatus as claimed in claim 1 further including a plurality of piston members and a plurality of clutch engagement detecting means corresponding to said plurality of piston cylinders of said speed-changing clutches, each piston member being disposed at a position where hydraulic pressure same to the hydraulic pressure of said clutch port acts, said piston member being effected by the hydraulic pressure of said clutch port in one direction and being forced by a predetermined resilient force of a spring in the other direction and each clutch engagement detecting means being adapted for detecting engagement of said speed-changing clutch on the basis of the displacement of said piston member, and wherein said control means detects a double engagement of speed-changing clutches on the basis of detection outputs of said plurality of clutch engagement detecting means.

9. The apparatus as claimed in claim 8, wherein said piston member is so set that said predetermined resilient force of said spring is appreciably larger than an initial pressure for the clutch on the completion of filling of the oil.

10. The apparatus as claimed in claim 8, wherein said clutch engagement detecting means comprises a member disposed at a position opposed to an end of said piston member and contact and noncontact detecting means for detecting contacting of said piston member with said member and parting of the former away from the latter.

11. The apparatus as claimed in claim 10, wherein said member comprises an electrically conductive housing cover disposed on a valve housing enclosing said pressure control valve and said flow rate detecting valve with an electrical insulating member interposed therebetween, and wherein said contact and noncontact detecting means is such that contacting of said piston member with said member and parting of the former away from the latter are represented in the form of an electric ON or OFF signal.

12. The apparatus as claimed in claim 11, wherein said contact and noncontact detecting means comprises voltage apply means for applying a predetermined intensity of voltage to said housing cover and voltage detecting means for detecting a voltage appearing on said housing cover when said piston member comes in contact with said housing cover and the former is parted away from the latter.

13. The apparatus as claimed in claim 1, wherein said second spool of said flow rate detecting valve is such that a pressure receiving area of said second spool located on the side where said flow rate detecting valve functions in the direction of closing is determined larger than that located in the side where said flow rate detecting valve functions in the direction of opening.