JPH0544743A - Hydraulic power transmission device - Google Patents

Abstract

PURPOSE:To set a device free during cornering and prevent a tight corner braking phenomenon from occurring as well as to make improvements in fuel consumption and derivability, in a hydraulic power transmission device used with a pair of hydraulic power transmission couplings. CONSTITUTION:A pair of hydraulic power transmission couplings 21 are installed in each space among three shafts relatively rotatable with one another, and torque conformed to each rotational speed difference between the first and second shafts as well as the first and the third shafts is transmitted, while a spool valve 70, opening pressure in a high pressure chamber 72, is installed in each of paired valve elements 45, 46, and when respective positional relations of these valve elements 45 and 46 are reversed, they are constituted so as to be opened in having the spool valve 70 operated onto a cam face 71 installed these opposed valve elements 45 and 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic power transmission device using a pair of hydraulic power transmission joints.

[0002]

2. Description of the Related Art A four-wheel drive vehicle equipped with a conventional power transmission device is shown in FIG. In FIG. 13, 1 and 2 are front wheels, and 3,
Reference numeral 4 is a rear wheel, and a viscous joint 5 is arranged between the front wheels 1 and 2 and the rear wheels 3 and 4. Reference numerals 6 and 7 are differential devices for the front wheels 1 and 2 and the rear wheels 3 and 4, and these differential devices 6 and 7 are respectively provided with viscous joints 8 and 9 for limiting the differential between the left and right wheels. ing. In addition, 10 is an engine.

In this case, since the conventional differential devices 6 and 7 between the left and right wheels are provided, there is a problem that the cost becomes high. As a solution to this, for example, as shown in FIG. 14, there is one in which the differential device 6 is eliminated and independent viscous joints 11 and 12 are provided for the left and right wheels, respectively.

[0004]

However, in both of the conventional examples as described above, the torque characteristics of the viscous joint are, as shown in FIG. Braking phenomenon is likely to occur, and large torque is transmitted even with a slight differential during normal driving, resulting in large drive loss, poor fuel economy of the vehicle, and large on rough roads with high differential. Since the torque cannot be transmitted, there is a problem that the running performance is deteriorated.

The present invention has been made in view of the above-mentioned conventional problems, and it is made free during cornering of a paved road to prevent the occurrence of a tight corner braking phenomenon, and the fuel consumption and the running performance are improved. It is an object of the present invention to provide a hydraulic power transmission device capable of improving the above.

[0006]

In order to achieve the above object, the present invention is provided between three shafts that can rotate relative to each other, is connected to a first shaft, and has two or more ridges on both inner side surfaces. A housing having a pair of cam surfaces having a plurality of cam surfaces; and a plurality of plunger chambers facing the cam surfaces, the plurality of plunger chambers being connected to the second or third shaft and rotatably and oppositely housed in the housing. And a pair of rotors formed in the axial direction, and housed in each of the plurality of plunger chambers so as to be reciprocally movable under the pressure of the return spring and A plurality of plungers that are driven by the cam surface when the shafts rotate relative to each other; suction and discharge holes that open to one end surface of the rotor that does not house the plunger and that communicate with the plunger chamber;
A plurality of suction ports that are rotatably slidably in contact with the end surface of the rotor and that are positioned so as to be rotatable by a predetermined angle with respect to the housing, and that act as suction valves and discharge valves depending on the positional relationship with the suction and discharge holes; A pair of valve bodies having discharge ports formed on the surface, a high pressure chamber formed by communicating the discharge ports of the valve bodies, an orifice provided between the high pressure chamber side and a low pressure chamber in the housing, and the pair of A thrust bearing is provided between the opposite back surfaces of the valve body of
And transmitting torque according to the rotational speed difference between the second and first and third shafts, and to each of the pair of valve bodies,
A switching valve that releases the pressure in the high-pressure chamber is provided, and when the positional relationship of the valve elements is reversed, the switching valve is operated and opened on the cam surface provided on the opposing valve elements. is there.

[0007]

In the present invention, the hydraulic power transmission joints that operate independently on the left and right sides are housed in the housing to transmit torque according to the differential rotation between the housing and the left and right wheels. That is, when the plunger is pushed by the pair of cam surfaces formed on both inner side surfaces of the housing and the pushed oil passes through the orifice, the hydraulic pressure in the plunger chamber increases due to the resistance of the orifice, and the reaction force is applied to the plunger. Occur. Torque is generated by rotating the housing having the cam surface against the plunger reaction force. This torque becomes proportional to the square of the differential rotation.

Because of such torque characteristics,
With a low differential, torque is small, a tight corner braking phenomenon does not occur, and only a small torque is transmitted during normal running with a small differential, so driving loss is small and fuel consumption can be improved. Further, since the torque is large when the differential is high, the running performance on a bad road can be improved.

On the other hand, during turning of the vehicle on the paved road, there is the following relationship among the tire rotation Nin on the inner wheel side, the tire rotation Nout on the outer wheel side, and the housing (differential case) rotation NS. Nin <NS <Nout Therefore, when the housing is considered as a reference, the left and right wheels and the housing are in opposite directions of differential rotation.

When the differential direction is reversed and the phase of the valve element is reversed, the switching valve (spool valve) moves along the cam surface formed on the valve element facing the valve and opens. Speak
Oil escapes from the high pressure valve. In this way, the free state can be obtained. That is, since the transmission torque can be made almost "0" during the cornering on the paved road, the cornering characteristic becomes equal to 2WD, and the occurrence of the tight corner braking phenomenon can be prevented.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 12 are views showing an embodiment of the present invention. As shown in FIG. 3, in the case of an FR vehicle, the hydraulic power transmission device 21 according to the present invention has axle shafts (second or third shafts) 24, 25 of the front wheels 22, 23 and a rear wheel 2.
It is provided between the three shafts of a propeller shaft (first shaft) 29 connected to the differential device 28 of 6, 27.

Further, in the case of an FF vehicle, as shown in FIG. 4, it is provided between the three axles of the axle shafts 30 and 31 of the rear wheels 26 and 27 and the propeller shaft 29. Next, the internal structure of the hydraulic power transmission device 21 is shown in FIGS. 1 and 2. 1 and 2, reference numeral 32 denotes a differential case (housing) connected to a propeller shaft 29 which is a first shaft. The differential case 32 has a pair of cam surfaces 33 having two or more ridges on both inner side surfaces. 34 are formed respectively.

Reference numerals 35 and 36 denote a pair of rotors connected to the axle shafts 24, 25 or 30, 31 which are the second or third shafts, and the rotors 35 and 36 are rotatably housed in the differential case 32. Axle shaft 2
It rotates together with 4, 25, or 30, 31. The rotors 35 and 36 include a plurality of plunger chambers 3 in the axial direction.
7, 38 are formed, and a plurality of plungers 39, 40 are provided in the plunger chambers 37, 38 with the return spring 4
It is slidably accommodated via 1, 42. Further, the rotors 35, 36 are formed with a plurality of suction / discharge holes 43, 44 so as to communicate with the plunger chambers 37, 38.

45 and 46 are suction ports 47 and 4 on the surface.
8, a pair of rotary valves (valve bodies) in which suction passages 49, 50 and discharge ports 51, 52 are formed, and the discharge ports 51, 5 are provided on the back surfaces of the rotary valves 45, 46.
Communication grooves 53, 54 are formed so as to communicate with each of the two. Rolling wheels 55 and 56 are provided in close contact with the back surface.

Then, the communication grooves 53, 54 and the suction port 4
One or a plurality of orifices (flow resistance generating means) 57 and 58 are formed between the nozzles 7 and 48. One orifice may be formed between each of the discharge ports 51 and 52 and the low pressure chamber in the differential case 32. Further, the rotary valves 45 and 46 have positioning projections 60 that engage with the notches 59 formed in the inner circumference of the differential case 32, respectively.

The rotary valves 45 and 46 constitute a timing member that determines the opening / closing timing of the intake / discharge holes 43 and 44, and the notch 59 and the projection 60 establish the phase relationship between the cam surfaces 33 and 34 and the rotary valves 45 and 46. It constitutes a positioning mechanism for regulation. When the plungers 39 and 40 are in the suction stroke, the suction ports 47 and 48 of the rotary valves 45 and 46 and the suction and discharge holes 43 of the rotors 35 and 36,
44 is in a positional relationship so that the orifices 57, 58,
Suction ports 47, 48, suction passages 49, 50, rotor 3
Oil can be sucked into the plunger chambers 37, 38 through the suction / discharge holes 43, 44 of the valves 5, 36.

When the plungers 39 and 40 are in the discharge stroke, the relationship is the reverse of the suction stroke, and the rotor 3
The intake / discharge holes 43 and 44 of the rotary valves 4 and 5 are
5, 46 discharge ports 51, 52 through the communication groove 53,
It leads to 54. Rotary valve 45 and rotary valve 4
6, a needle bearing (thrust bearing) 61 is interposed, and the friction torque on the needle bearing 61 side is set to be smaller than the friction torque between the rotors 35 and 36 and the rotary valves 45 and 46. There is. Therefore, when the direction of the differential rotation is changed, the rotary valves 45 and 46 move to the rotors 35 and 3.
After rotating together with 6, the protrusion 59 for positioning the rotary valves 45, 46 rotates until it contacts the notch 60 of the differential case 32, and then rotates together with the differential case 32. As a result, the intake / discharge holes 43, 44 are forcibly opened / closed at a predetermined timing even during normal rotation or reverse rotation.

Incidentally, 63 and 64 are accumulator pistons, 65 and 66 are oil seals, and 67 is a separate plate. Here, in the rotary valves 45 and 46,
A spool hole 69 is formed, and a spool valve 70, which is a switching valve for opening the high pressure chamber, is inserted into the spool hole 69. A cam surface 71 for controlling the entrance and exit of the spool valve 70 is formed on the opposing rotary valves 45 and 46. The rotary valve 45, 46 has a discharge port 5
A high-pressure chamber 72 communicating with 1, 52 is formed.
Is closed by the spool valve 70 in the torque transmission state,
The differential direction of the left and right wheels is reversed and the rotary valve 45,
The spool valve 70 is adapted to open when the phase of 46 is reversed.

As shown in FIG. 5, the spool valve 70 has a large diameter portion 73, a small diameter portion 74 and a stepped pressure receiving surface 75,
Since the pressure from the high-pressure chamber 72 is constantly applied to the stepped pressure receiving surface 75, a force is applied in the leftward direction indicated by the arrow G as shown in FIG. Therefore, the spool valve 70 can move along the cam surfaces 71 of the opposing rotary valves 45 and 46 without a spring or the like. In addition, 7
6 is a blind cover.

Next, the operation will be described. When there is no rotation difference between the differential case 32 and the rotors 35 and 36, the plungers 39 and 40 do not operate and torque is not transmitted. At this time, the plungers 39 and 40 are pressed against the cam surfaces 33 and 34 by the return springs 41 and 42.

Next, the differential case 32 and the rotors 35 and 36
When there is a difference in rotation between the pistons 39 and 40 in the discharge stroke, the cam surfaces 33 and 34 of the differential case 32 push the plungers 39 and 40 in the axial direction. At this time, the suction / discharge holes 43, 4
Since 4 communicates with the discharge ports 51, 52, the plungers 39, 40 push the oil in the plunger chambers 37, 38 from the suction / discharge holes 43, 44 to the discharge ports 51, 52 of the rotary valves 45, 46.

The oil pushed out to the discharge ports 51 and 52 is supplied to the suction ports 47 and 48 through the communication grooves 53 and 54 and the orifices 57 and 58. At this time, the hydraulic pressures of the communication grooves 53, 54, the discharge ports 51, 52 and the plunger chambers 37, 38 rise due to the resistance of the orifices 57, 58, and a reaction force is generated in the plungers 39, 40. A torque is generated by rotating the differential case 32 against the plunger reaction force, and the differential case 32 is rotated.
Torque is transmitted between the rotor and the rotors 35 and 36. Since the discharge ports 51 and 52 are communicated with each other through the communication grooves 53 and 54, the hydraulic pressures of all the plunger chambers 37 and 38 in the discharge stroke are equal.

Further, when the differential case 32 rotates, a suction stroke occurs, and the suction and discharge passages 43 and 44 are connected to the suction port 4
In order to communicate with 7, 48, the oil in the suction passages 49, 50 is
The plunger 3 is sucked into the plunger chambers 37 and 38 through the suction ports 47 and 48 and the suction and discharge holes 43 and 44.
9 and 40 return along the cam surfaces 33 and 34 of the differential case 32.

As shown in B of FIG. 12, the torque T has a torque characteristic that increases with the square of the differential rotation speed ΔN. Therefore, when the differential is low, the torque is small, the tight corner braking phenomenon does not occur, and during normal driving, a large differential torque is transmitted even with a slight differential, so that the drive loss is small and the fuel efficiency of the vehicle is improved. it can.

Since the torque is large when the differential is high,
It is possible to improve running performance on rough roads. On the other hand, as shown in FIGS. 7 and 8, the tire rotation Nin on the inner wheel side and the tire rotation Nou on the outer wheel side during the turning of the vehicle on the pavement.
There is the following relationship between t and the differential case rotation NS.

Nin <NS <Nout Therefore, when the differential case 32 is considered as a reference, the left and right wheels and the differential case 32 are rotated in opposite directions.
As shown in A of FIG. 9, when the rotational directions D of the rotary valves 45 and 46 with respect to the differential case 32 are the same, as shown in A of FIG. 10 and A of FIG. It abuts the valves 45 and 46 and is closed. Therefore, there is no escape of oil from the high pressure chamber 72, and torque is transmitted (see FIG. 11, A).

As shown in FIG. 9B, when the rotational directions E of the rotary valves 45 and 46 with respect to the differential case 32 are reversed, the spool valve 70 is relatively moved as shown in FIG. 10B and FIG. 11B. The rotary valves 45 and 46 move along the cam surfaces 71 of the rotary valves 45 and 46 to be in the open state. Therefore, as shown by the arrow F, the oil escapes from the high-pressure chamber 72 and becomes free (see FIGS. 11 and B).

As described above, the corner is free during cornering on the pavement, so that the occurrence of the tight corner braking phenomenon can be prevented. Further, when the vehicle travels on a bad road, the tire slip is large, so that the rotation of the differential case 32 is faster than the rotation of the left and right wheels, and the differential directions of the left and right wheels are in phase. Therefore, a normal torque transmission state is achieved, and high running performance can be exhibited.

[0029]

As described above, according to the present invention, it is possible to maintain the free state during the cornering of the pavement, prevent the occurrence of the tight corner braking phenomenon, and improve the fuel consumption. You can Further, when traveling on a rough road with a high differential, a large torque can be transmitted to improve the running performance.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship between a rotary valve and a housing during forward / reverse rotation.

FIG. 3 is a diagram showing an example in which this device is installed in an FR vehicle.

FIG. 4 is a diagram showing an example in which this device is installed in an FF vehicle.

FIG. 5 is a diagram showing a spool valve.

FIG. 6 is a diagram showing pressure applied to a spool valve.

FIG. 7 is a diagram showing a turning distance when the vehicle turns.

FIG. 8 is a diagram showing a turning distance when the vehicle turns.

FIG. 9 is an explanatory diagram of a rotation direction

FIG. 10 is an explanatory diagram of a torque transmission state and a free state.

FIG. 11 is an explanatory diagram of a torque transmission state and a free state.

FIG. 12 is a graph showing torque characteristics.

FIG. 13 is a diagram showing a conventional example.

FIG. 14 is a diagram showing another conventional example.

[Explanation of symbols]

 21: Hydraulic power transmission device 22, 23: Front wheel 24, 25: Axle shaft 26, 27: Rear wheel 28: Differential device 29: Propeller shaft 30, 31: Axle shaft 32: Differential case (housing) 33, 34: Cam Surface 35, 36: Rotor 37, 38: Plunger chamber 39, 40: Plunger 41, 42: Return spring 43, 44: Suction / discharge hole 45, 46: Rotary valve 47, 48: Suction port 49, 50: Suction path 51, 52: Discharge port 53, 54: Communication groove 55, 56: Rolling wheel 57, 58: Orifice 59: Notch 60: Protrusion 61: Needle bearing (thrust bearing) 63, 64: Accumulator piston 65, 66: Oil seal 67: Separate plate 69: Spool hole 70: Spool valve 7 : Cam face 72: high-pressure chamber 73: large-diameter portion 74: small-diameter portion 75: stepped pressure receiving surface 76: blind lid

Claims (2)

[Claims] 1. A shaft is provided between three shafts that can rotate relative to each other,
A housing connected to the first shaft and having a pair of cam surfaces having two or more peaks on both inner side surfaces; a housing connected to the second or third shaft and rotatably in the housing; A pair of rotors housed opposite to each other and axially formed with a plurality of plunger chambers facing the cam surface; each of the plurality of plunger chambers is reciprocally movable by receiving a pressing force of a return spring. A plurality of plungers that are housed and that are driven by the cam surface during relative rotation between the first and second or first and third shafts; and one end surface of the rotor that does not house the plunger. A suction / discharge hole communicating with the plunger chamber; rotatably slidably contacting an end face of the rotor and rotatably positioned by a predetermined angle with respect to the housing, and a position with respect to the suction / discharge hole A plurality of suction ports that act as suction valves and discharge valves by a pair of valves, a pair of valve bodies having discharge ports formed on the surface, a high-pressure chamber formed by communicating the discharge ports of the valve bodies, and the high-pressure chamber side. An orifice provided between the low-pressure chamber in the housing and a back surface of the pair of valve bodies facing each other is provided with a thrust bearing, which corresponds to the difference in rotational speed between the first and second shafts or the first and third shafts. A switching valve that transmits torque and releases the pressure in the high-pressure chamber is provided on each of the pair of valve bodies, and when the positional relationship of the valve bodies is reversed, the cam surfaces on the opposing valve bodies are A hydraulic power transmission device characterized in that the switching valve is operated to open. 2. The hydraulic power transmission device according to claim 1, wherein the switching valve has a spool shape, and a stepped pressure receiving surface for generating a load in the opening direction by the pressure of the high pressure chamber is formed.