JPH0341225A - Power transmission for vehicle - Google Patents

Abstract

PURPOSE:To create 2WD condition in tight corner and 4WD in the other places by detecting hydraulic oil temperature and steering angle, comparing them with specified values by a control means, and controlling a valve means for draining hydraulic oil from a hydraulic oil pump according to the compared results. CONSTITUTION:Specified values t0 and theta0 for oil temperature and steering angle are set in a control unit, respectively. When a value theta is input, signals for the oil temperature and the steering angle are also compared with each other, respectively. When t < t0 and theta > theta0, a solenoid coil 44 is energized by a control signal from the control unit. A needle valve 40 is moved rightwards against a spring 42 to open a relief hole 84. Thus, when the oil temperature is less than a specified limit and the steering angle exceeds it, a vehicle is judged to be positioned at a tight corner and 2WD running condition is created. Accordingly, the production of tight-corner braking trouble at low temperatures can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power transmission device for a vehicle having a hydraulic power transmission joint.

[Prior art] Four-wheel drive (4-wheel drive) in which the front and rear wheels are driven by the same engine
In 4WD (4WD) cars, there is a slight difference in the effective radius of the front and rear tires, and when turning, the front wheels have a larger turning radius than the rear wheels, so the front and rear wheels are forced to drive in order to turn faster. Torsional torque is generated between the shafts, resulting in the same state as braking, resulting in the so-called tight corner braking phenomenon, which deteriorates driving performance.
Tire wear occurs.

For this reason, for example, in JP-A-61-249828, the oil temperature of the hydraulic pump is detected by an oil temperature sensor, and when the oil temperature is below a certain value, the orifice is opened to avoid the tight corner braking phenomenon. Something like this has been proposed.

[Problems to be Solved by the Invention] However, in such conventional power transmission devices, when the oil temperature is below a certain value, that is, when the temperature is low, the viscosity of the hydraulic oil is high, and the difference in rotational speed between the front and rear wheels increases. Even if the torque is small, the torque will be large, so the orifice is opened to avoid the tight corner braking phenomenon, but even if it is not a tight corner and you originally want to drive in 4WD, the
Since the vehicle runs in D, there is a problem in that running performance and steering stability deteriorate.

The present invention has been made in view of these conventional problems.
It is an object of the present invention to provide a power transmission device for a vehicle that improves all-terrain performance and maneuverability by setting the drive state to WD.

[Means for Solving the Problem] In order to achieve the above object, the present invention provides a hydraulic pump driven by a rotational speed difference between a first rotating member and a second rotating member that are relatively rotatable. , a hydraulic power transmission joint having a variable orifice mechanism provided in a discharge path of the hydraulic pump, and a valve means for releasing hydraulic oil from the hydraulic pump in response to an external signal; and an oil temperature for detecting the temperature of the hydraulic oil. The control means includes a control means for inputting an oil temperature signal and a steering angle signal from a detection means and a steering angle detection means for detecting a steering angle and comparing them with respective predetermined values, and controlling the valve means based on the comparison results.

[Function] In the present invention, when the oil temperature is less than a predetermined value and the steering angle exceeds a predetermined value, it is determined that the corner is in a tight corner and the 2WD is set. When the steering angle is less than a predetermined value even if it is less than a predetermined value, it is determined that the vehicle is in a corner other than a tight corner, and 4WD is set.

Therefore, it is possible to prevent the tight corner braking phenomenon from occurring when cornering is tight, and it is possible to improve running performance and maneuverability of the wheels when the vehicle is not cornering in tight corners.

[Example] Embodiments of the present invention will be described below based on the drawings.

1 to 5 are diagrams showing one embodiment of the present invention, which is applied to a vehicle based on a rear wheel drive vehicle.

First, to explain the configuration, in Fig. 1, the top is the front drive shaft (first rotating member) which is the output shaft (
The rotor 1 is rotatably supported by the casings 2 and 3 via bearings 4.5.

A driven sprocket 7 is rotatably supported on the rotor 1 via a needle bearing 6, and a chain 9 is installed between the driven sprocket 7 and the drive sprocket 8. In addition, 10 is an output flange, 11 is a nut, 12.13 is an oil seal, ↓4 is a stop ring, and 15 is a thrust washer.

A plurality of plunger chambers 16 are formed in the rotor 1 in the axial direction, and a plurality of plungers 17 that reciprocate in the axial direction are housed in the plunger chamber 6. A cam surface 18A is formed on the inner surface of a cam housing (second rotating member) 18 fixed to the driven sprocket 7, and the plunger 17 is in sliding contact with the cam surface 18A. Note that the plunger 17 and the plunger chamber 16 collectively constitute a hydraulic pump.

19 is a suction passage communicating with the plunger chamber 16, and a suction valve 20 is interposed in the suction passage 19. That is,
The suction valve 20 is provided coaxially with the plunger chamber 16 and at the bottom. 21 is a return spring that holds the suction valve 20, and a plug 22 that holds this return spring 2 is held by the return spring 23 of the plunger 17.

Reference numeral 24 denotes a discharge passage that opens in the side wall of the plunger chamber 16 and is formed toward the center of the mouthpiece 1. A discharge valve 25 is interposed in the discharge passage 24 via a return spring 26.

Further, 81 is a needle valve (variable orifice mechanism) movably housed in the housing hole 82 of the plug 31, and 83 is an orifice whose opening area is variable by the needle valve 82.

Further, a main passage 27 is formed in the center of the rotor 1, and the main passage 27 is connected to the discharge passage 24 through the relief hole 84.
The high pressure chamber 29 communicates with the high pressure chamber 29 .

Further, the main passage 27 communicates with the suction passage 19 via a passage 30 formed in the rotor 1.

Further, 31 is a plug that holds the return spring 26, 32 is a piston, and 33 is a spring that holds the piston 32. Also, 34°35 is an oil seal,
36 is a stop ring, and 37 is a thrust washer.

Reference numeral 38 denotes a valve means for opening and closing the relief hole 84, and the valve means 38 is composed of a non-magnetic cylindrical body 39 and a needle valve 40 housed within the cylindrical body 39 and made of a movable magnetic material. The needle valve 40 has a communication hole 41 formed therein and is biased by a return spring 42 .

A magnetic frame 43 is fixed to the casing 3 and forms a magnetic circuit. The magnetic frame 43 is held in a non-contact state by the non-magnetic cylinder 39 inside the rear end of the needle valve 40, and has a solenoid coil 44 inside. is stored. In addition, 46
is a cover provided on the magnetic frame 43.

Next, FIG. 2 shows the arrangement of the joints.

In FIG. 2, 51 is an engine, 52 is a transmission, and 53 is a transfer.

A main shaft 54 is rotatably supported within the transfer 53 by the casings 2 and 3 via bearings 55 and 56, and the main shaft 54 is provided with a drive sprocket 8. A driven sprocket 7 connected to a drive sprocket 8 by a chain 9 is rotatably supported by the rotor 1 via a needle bearing 6. The rotor 1 incorporates the joint 57 described above.

In addition, 58 is the right front wheel, 59 is the left front wheel, 60 is the right rear wheel, 6
1 is the left rear wheel, 62 is the front wheel side differential gear device,
63 is a rear wheel side differential gear device, 64 is a front wheel side propeller shaft, and 65 is a rear wheel side propeller shaft.

91 is an oil temperature sensor, and the oil temperature sensor 91 is provided inside the casing 3. Let the temperature detected by the oil temperature sensor 91 be the temperature of the hydraulic oil in the joint 57.

The oil temperature signal detected by the oil temperature sensor 91 is manually input to a control unit 92 as a control means, as shown in FIG. Further, a steering angle signal from a steering angle sensor 93 that detects the steering angle of the steering wheel is input to the control unit 92.

The control unit 92 compares the oil temperature signal and the steering angle signal with predetermined values, and sends a control signal to the solenoid coil 44 based on the comparison result.

Next, the effect will be explained.

FIG. 4 shows a control routine for controlling the joint.

In FIG. 4, first, in step S1, initial values, that is, a predetermined value to of the oil temperature and a predetermined value θ0 of the steering angle are set in the control unit 92, respectively. Next, in step S2, the oil temperature signal t and the steering angle signal θ are respectively input. Then, in step S3, t and to are compared, and then in step S4, θ and 00 are compared.

When t<to, θ>θ0, the solenoid coil 44 is turned on by a control signal from the control unit 92 in step S5.

When the solenoid coil 44 is turned on, the needle valve 40 moves to the right against the return spring 42 to open the relief hole 84.

Therefore, it becomes a free state as shown in E of FIG.

In this way, when the oil temperature is less than the predetermined value to and the steering angle exceeds the predetermined value θ0, it is determined that the vehicle is in a tight corner and the vehicle is in a 2WD driving state. This makes it possible to prevent tight corner braking from occurring at low temperatures.

Next, when t≧to in step S3, the solenoid coil 44 is turned off in step S6. Further, when θ≦00 in step S4, the solenoid coil 44 is turned off in step S6.

When t≧to, there is almost no change in the torque characteristics,
It can be determined that there is a corner other than a tight corner, and
This is because even when t<to and θ≦00, it can be determined that the corner is other than a tight corner.

When the solenoid coil 44 is turned off, as shown in FIG. 5, the normal characteristic as shown in A is maintained until the discharge pressure P1 is reached. Note that when the discharge pressure P reaches Pl, the orifice 83 is closed to the needle pulp 81 and becomes locked (see B), and when the discharge pressure P reaches P2, the needle pulp 4o constituting the valve means 38 is closed. It moves to the right against the return spring 42 to open the relief hole 84, resulting in a relief characteristic (see C1).

In this way, at low temperatures, 4W outside of tight corners
D running state can be achieved, and running performance and steering stability can be improved.

[Effects of the Invention] As explained above, 2WD is used when entering a tight corner where the oil temperature is less than a predetermined value and the steering angle exceeds a predetermined value, and 4WD is used outside of a tight corner, thereby preventing the occurrence of tight corner braking during tight corners. This makes it possible to improve the drivability and maneuverability of the wheels outside of tight corners.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a view showing the arrangement of the joint, FIG. 3 is a view showing the control unit, FIG. 4 is a flowchart showing the control routine, and FIG. It is a graph showing torque characteristics. In the figure, 1... Rotor (first rotating member), 2.3... Casing, 4.5... Bearing, 6... Needle bearing, 7... Driven sprocket, 8... Drive sprocket, 9... Chain, 10... Output flange, 11... Nut, 12.13... Oil seal, 14... Stop ring, 15... Thrust washer, 16... Plan Jar chamber, 17... Plunger 18... Cam housing (second rotating member) 18A.
...Cam surface, 19...Suction path, 20...Suction valve, 21...Return spring, 22...Plug, 23...Return spring, 24...Discharge path, 25... Discharge valve, 26... Return spring, 27... Main passage, 29... High pressure chamber, 30... Passage, 31... Plug, 32... Piston, 33... Return spring, 34 .35... Oil seal, 36... Stop ring, 37... Thrust washer, 38... Valve means, 39... Cylindrical body, 40... Needle valve, 41... Communication hole, 42... Return spring, 43... Magnetic frame, 44... Solenoid coil, 46... Cover 51... Engine, 52... Transmission, 53... Transfer 54... Main shaft, 55.56...Bearing, 57...Joint, 58...Right front wheel, 59...Left front wheel, 60...Right rear wheel, 61-...Left rear wheel, 62...Front wheel Side differential gear device, 63...
- Rear wheel side differential gear device, 64... Front wheel side propeller shaft, 65... Rear wheel side propeller shaft, 81... Needle valve (variable orifice mechanism) 82
... Storage hole, 83 ... Orifice, 84 ... Relief hole, 9↓ ... Oil temperature sensor (oil temperature detection means), 92 ... Control unit (control means), 93 ... Steering Angle sensor (steering angle detection means).

Claims (1)

[Claims] A hydraulic pump driven by a rotational speed difference between a first rotating member and a second rotating member that are relatively rotatable, a variable orifice mechanism provided in a discharge path of the hydraulic pump, and a hydraulic pump driven by an external signal. a hydraulic power transmission joint having a valve means for releasing hydraulic oil from the hydraulic oil; an oil temperature signal and a steering angle signal from an oil temperature detection means for detecting the temperature of the hydraulic oil and a steering angle detection means for detecting a steering angle; 1. A power transmission device for a vehicle, comprising: a control means that compares an input with each predetermined value and controls the valve means based on the comparison result.