JPH05340432A - Speed difference sensitive coupling - Google Patents

Abstract

PURPOSE:To prevent a cam surface from being worn away by keeping off an oil film break in a sliding part between the cam surface and a piston, in a speed difference sensitive coupling. CONSTITUTION:A center line H of a cam surface 31 in a housing member 4 and a piston turning shaft P1 of a drive piston 50 are installed after being offset as far as a distance (e), and two sliding points S1, S2 between the cam surface 31 and the drive piston 50 are also offset as far as another distance E to both piston turning shafts P1 and P2, through which the drive piston 50 is rotated and each oil film is formed in both these sliding points S1 and S2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation difference sensitive joint which is applied to, for example, a drive system of a vehicle and which obtains a joint transmission torque according to a relative rotation difference between drive input / output members.

[0002]

2. Description of the Related Art As a conventional rotation difference sensitive joint, there is one disclosed in JP-A-63-285334.

In this structure, a housing member and a rotor member are coaxially rotatably arranged, and a piston is provided radially on the rotor member so as to slide on a cam surface formed on the inner surface of the housing member. It is adapted to reciprocate in the radial direction by sliding on the cam surface. The outflow of the fluid discharged when the piston moves toward the center of the rotor member is regulated by the orifice, and the piston is pressed against the cam surface by the fluid pressure generated at this time, so that the housing member and the rotor member are separated from each other. Torque is transmitted.

In particular, as shown in FIG. 7, as means for preventing wear of the sliding portion of the cam surface, the cam surface is formed by two arcs having different radii, and the sliding portion with the piston is relative to the central axis of the piston. It is shown to be two points in opposite positions but at different distances from this axis. In this case, the rotational moment due to the sliding friction between the two sliding parts is made uneven, and the piston is rotated, and the oil scraping action due to this rotation causes an oil film on the sliding part between the cam surface and the piston. And the abrasion of the cam surface was prevented by the lubricating action of oil.

[0005]

However, in the one shown in FIG. 7 of JP-A-63-285334, one sliding portion has one cam sliding direction of the oil by the cam surface and the other of the oil by the piston. Although the scraping direction is the same and the oil film formed is thicker than when the piston is not rotating, the lubricating effect of the oil is increased, but on the other sliding part, the scraping direction of the oil by the cam surface and the scraping direction of the oil by the piston are opposite. As a result, the oil film formed becomes thinner than when the piston is not rotating, and the lubricating action of oil is reduced. Therefore, there is a problem that the wear of the cam surface is accelerated.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent an oil film from running out at a sliding portion between a piston and a cam surface and reduce wear of the cam surface.

[0007]

In order to achieve the above-mentioned object, the rotation-difference sensitive joint according to claim 1 comprises a housing member and a rotor member which are coaxially and relatively rotatably arranged.
The cam surface provided on the inner surface of the housing member and the rotor member are radially arranged in the radial direction of the rotor member, and in the radial direction while sliding on the cam surface by relative rotation with the housing member. A reciprocating cylindrical piston, a fluid chamber provided in the rotor member, the volume of which changes with the reciprocating movement of the piston, and an orifice for restricting the outflow of fluid discharged by the reduction of the fluid chamber. In the rotation difference sensitive joint that converts the fluid pressure generated by the outflow regulation by the orifice into the transmission torque between the housing member and the rotor member, the sliding portion with the cam surface of the piston is connected in the reciprocating direction of the piston. The rotor member is provided offset to either side of the central axis in the axial direction of the rotor member.

In order to achieve the above object, in the rotation difference sensitive joint according to claim 2, the offset direction of the sliding portion of the piston located symmetrically with respect to the rotation axis of the rotor member is made different. The rotation difference sensitive joint according to claim 1 characterized.

[0009]

According to the rotation difference sensitive joint of claim 1, when a relative rotation difference occurs between the housing member and the rotor member, pistons radially arranged on the rotor member reciprocate in the radial direction while sliding on the cam surface. Move. The fluid discharged due to the contraction of the fluid chamber due to the reciprocating movement of the piston is regulated to flow out by the orifice to generate a fluid pressure, which is converted into a transmission torque between the housing member and the rotor member. At this time, since the sliding part between the piston and the cam surface is offset to either the axial direction of the rotor member, the piston rotates, and the oil scraping direction of the cam surface and the oil scraping direction of the piston match. As a result, the oil film formed on the sliding portion becomes thicker and the lubricating action increases.

According to a second aspect of the present invention, in addition to the action of the first aspect of the invention, the offset of the sliding portion between the housing member, the rotor member and the cam surface of the piston located symmetrically with respect to the rotation axis is provided. Since the directions are made different, the force of pushing one piston in the axial direction of the rotor member cancels out the force of pushing the other piston in the symmetrical position in the axial direction of the rotor member, and as a result, The rotor member and the housing member are positioned.

[0011]

Embodiments of the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a schematic view showing a relationship between a cam surface and a piston of a control type rotational differential sensing joint which is an embodiment of the present invention,
FIG. 2 is a cross-sectional view showing a transfer in which a control type differential rotation sensitive joint which is an embodiment of the present invention is applied as a torque distribution device, and FIG. 3 is a schematic view showing a vehicle drive system and a control system to which this embodiment is applied. FIG. 4 is a graph showing the relationship between the relative transmission difference between the rotor member and the housing member and the joint transmission torque in this control type rotation difference sensitive joint.

As shown in FIG. 3, in the vehicle drive system of this embodiment, the driving force generated by the engine 76 is transmitted to the transfer 53 via the transmission 74 and the transmission output gear 93, and a part of the driving force is transmitted. The left rear wheel 9 is transferred from the transfer 53 through the transfer gear 94, the propeller shaft 81, and the rear differential 82.
2, transmitted to the right rear wheel 88. On the other hand, the remaining driving force is transmitted from the transfer 53 to the left front wheel 76 and the right front wheel 84 via the front differential 32.

The front differential 32 is built in a transfer case 38, and a control type rotation difference sensitive joint (rotation difference sensitive joint) 25 having a torque distribution function is provided on the left front wheel 76 side. Therefore, when a relative rotation difference occurs between the front and rear wheels, the joint transmission torque generated in the control-type rotation difference sensitive joint 25 becomes the driving force distributed to the front wheels. Although the control type rotational difference sensitive joint 25 is provided only at the left side gear position, the left front wheel 76 and the right front wheel 8 are transmitted due to the torque equal distribution transmission action by the differential 32.
The same torque is transmitted to 4.

Further, the joint transmission torque characteristic of the control type rotational difference sensitive joint 25 can be changed by driving the motor actuator 62.
Are controlled by the controller 78.

The controller 78 includes signals from a right front wheel speed sensor, a left front wheel speed sensor, a right rear wheel speed sensor, a right rear wheel speed sensor, a left rear wheel speed sensor, a lateral G sensor, an accelerator opening sensor, and an engine speed signal, which are not shown. , ABS control signal, etc. are input,
These signals are used as input information, and change control of the joint transmission torque characteristic is performed according to the rotational speed difference of each wheel, accelerator opening degree, etc., and release control is performed during ABS operation.

As shown in FIG. 2, the transfer case 38 is rotatably supported by the transfer housing 54, and the ring gear 28 meshing with the transmission output gear 93 (not shown) is fixed to the outer peripheral flange portion with bolts 29. It is connected to a transfer gear 94 (not shown).

The front differential 32 is a pinion shaft 3 supported by a transfer case 38.
4, a pinion 36 rotatably supported by the pinion shaft 34, and a pair of side gears 46 and 48 meshing with the pinion 36.

The side gear 48 is spline-coupled to the left front wheel shaft 42 via the control type rotation difference sensitive joint 25, and the side gear 46 is spline-coupled to the right front wheel shaft 44.

The motor actuator 62 is fixed to the transfer housing 54, and is provided with a fork 66 provided on the motor shaft 64, an outer sleeve 68 in contact with the fork 66, and a bearing 58 on the outer sleeve 68. Inner sleeve 56 and cross rod 72 fixed to the inner sleeve 56
The position of the spool 69 fixed to the other end of the push rod 52 is changed by the push rod 52 disposed at the axial center position of the left front wheel shaft 42 and having one end fixed to the cross rod 72. is there. The motor actuator 62 and the motor shaft 64 are drawn with their cross sections changed by 90 °.

The control type rotational differential responsive joint 25 includes a housing member 4 integrally formed with a side gear 48 and a cam surface 31 on an inner surface thereof, a rotor member 2 splined to a left front wheel shaft 42, and Housing member 4
Of the drive piston (piston) 50 radially arranged to reciprocate in the cylinder hole 41 provided in the rotor member 2 while slidingly contacting the cam surface 31 due to a relative rotation difference between the drive piston 50 and the rotor member 2. A cylinder chamber (fluid chamber) 60, the volume of which changes with the reciprocating movement of the rotor chamber, a spool chamber 70 provided at the axial center position of the rotor member 2, and an orifice 8 for communicating the spool chamber 70 with the cylinder chamber 60. It has a discharge passage 71, a spool 69 provided in the spool chamber 70 so as to be axially strokeable, and changing the opening area of the orifice 8, and an accumulator chamber 90 formed at an end position of the spool 69.
Further, the cup seal 5 is provided on the outer periphery of the drive piston 50 so that oil does not leak from the sliding surface with the cylinder hole 41.
1 is provided.

A regulator oil passage 80 is formed in the rotor member 2 to connect the accumulator chamber 90 and the cylinder chamber 60 via a one-way valve 81. The accumulator chamber 90 is formed by a cylindrical insertion hole 16 provided coaxially with the rotor member 2 and an accumulator piston 6 that slides in the insertion hole 16.

As shown in FIG. 1, the relationship between the cam surface 31 and the drive piston 50 is the piston center axis P1 of the drive piston 50 shown on the upper side in the figure with respect to the cam surface center line H of the housing member 4. The piston center axis P2 of the drive piston 50 shown in the lower side in the figure at a position symmetrical with respect to the rotation axis R of the drive piston 50 and the rotor member 2 is provided by being offset by e. It is provided by being offset from H by e in a direction opposite to the central axis P1. Therefore, the sliding portion S1 between the upper drive piston 50 and the cam surface 31 in the figure is
Is offset by E on the left side in the figure with respect to the piston center axis P1, and the sliding portion S2 between the drive piston 50 and the cam surface 31 on the lower side in the figure is by E on the right side in the figure with respect to the piston rotation axis P2. It is just offset.

Next, the operation will be described.

For example, when the vehicle turns, since the loci of the front wheels and the rear wheels are different, a difference in rotation occurs between the front and rear wheels, and a relative difference in rotation occurs between the housing member 4 and the rotor member 2.
When a relative rotation difference occurs between the housing member 4 and the rotor member 2, the drive piston 50 that strokes in the axial direction
The fluid pressure is generated in the cylinder chamber 60 by restricting the outflow of the oil discharged from the spool chamber 70 to the accumulator chamber 90 through the discharge passage 71 from the cylinder chamber 60 by the orifice 8. The oil discharged to the accumulator chamber 90 returns to the cylinder chamber 60 through the regulator oil passage 80 when the drive piston 50 makes a radial stroke due to the pressure applied by the accumulator piston 6.

At this time, the pressing force with which one drive piston 50 is pressed against the cam surface 31 is obtained.

When the phase angle between the rotor member 2 and the housing member 4 is θ and the function of the piston stroke determined by the cam surface is R (θ), the piston stroke speed VP (m / sec) at the rotation difference n (rpm). ) Is

[0028]

[Equation 1]

It becomes Assuming that the diameter of the drive piston is D, the diameter of the orifice is d, and the flow coefficient is c, the flow velocity VO at the orifice is

[0030]

[Equation 2]

Therefore, assuming that the fluid density is γ, the in-cylinder oil pressure p (Pa) is calculated from Bernoulli's theorem.

[0032]

[Equation 3]

Therefore, the hydraulic pressure force P (N) is

[0034]

[Equation 4]

It becomes Drive piston 5 by this force
0 comes into pressure contact with the cam surface 31, and a joint transmission torque corresponding to the relative rotation difference between the housing member 4 and the rotor member 2 is generated.

That is, the joint transmission torque is proportional to the square of the relative rotation difference between the housing member 4 and the rotor member 2, and is inversely proportional to the square of the opening area of the orifice 8. Therefore, as shown in the characteristic curve in FIG. 3, the joint transfer torque characteristic becomes a quadratic function curve having a gain according to the opening area of the orifice 8, and the gain is high on the fully closed side of the orifice 8 and low gain on the fully open side. Is decided. When the vehicle is traveling, the motor actuator 62 determines the axial position of the spool 69 that determines the opening area of the orifice 8 so that a desired joint transmission torque can be obtained according to a control signal from the controller 78.

In this embodiment, the drive piston 5
Since the sliding portion S1 between 0 and the cam surface 31 is offset by E with respect to the piston central axis P1, a rotational moment acts on the drive piston 50 to rotate it. That is,
The oil scraping direction of the cam surface 31 in the sliding portions S1 and S2 coincides with the scraping direction of the oil by the drive piston 50, so that an oil film is easily formed. Therefore, the lubricating effect of oil is increased, and wear of the cam surface 31 can be prevented. Further, the drive piston 50 itself also constantly moves the sliding portion due to the rotation, and wear can be reduced, so that the surface erosion phenomenon due to surface peeling or oil film breakage can be prevented.

When positioning is performed at another contact portion between the housing member 4 and the rotor member 2, driving loss occurs due to sliding friction at this portion, but as in the present embodiment.
The offset direction of the drive piston 50 symmetrical with respect to the rotation axis of the rotor member 2 is made different, and the thrust force in the right direction in FIG. By positioning the rotor member 2 and the housing member 4 so as to cancel out the thrust forces acting on the lower drive piston 50 and the cam surface 31 in the drawing in the left direction in the drawing,
Positioning between both members is accurately performed without causing drive loss, and highly accurate orifice opening characteristics, that is, transmission torque characteristics can be obtained.

[0039]

As described above, in the rotation difference responsive joint according to claim 1, when the housing member and the rotor member rotate relative to each other, the piston is rotated to prevent wear of the cam surface and the piston sliding portion. ..

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, since the positioning can be performed by the cam surface and the piston, as compared with the case where the positioning is performed by the rotor member and the other parts of the housing member, the driving is performed. Positioning between both members can be accurately performed without causing loss.

[Brief description of drawings]

FIG. 1 is a schematic view showing a relationship between a cam surface and a piston of a control type rotational difference sensitive joint which is an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a transfer to which the control type rotation difference sensitive joint according to the embodiment of the present invention is applied as a torque distribution device.

FIG. 3 is a schematic diagram showing an engine drive system and a control system to which this embodiment is applied.

FIG. 4 is a characteristic diagram showing a relationship between a relative rotation difference between a rotor member and a housing member of the control type rotation difference sensitive joint and a joint transmission torque.

[Explanation of symbols]

2 ... Rotor member, 4 ... Housing member, 8 ... Orifice, 25 ... Control type rotation differential joint (rotational differential joint),
31 ... Cam surface, 50 ... Drive piston (piston),
60 ... Cylinder chamber (fluid chamber), P1, P2 ... Piston rotation shaft (center axis of piston reciprocating direction), S1, S2 ... Sliding part, E ... Offset.

Claims (2)

[Claims] 1. A housing member and a rotor member coaxially rotatably arranged, a cam surface provided on an inner surface of the housing member, a rotor member provided on the rotor member, and radially arranged in a radial direction of the rotor member. And a cylindrical piston that reciprocates in the radial direction while sliding on the cam surface due to relative rotation with the housing member, and a fluid chamber that is provided in the rotor member and that changes in volume as the piston reciprocates And an orifice for restricting the outflow of the fluid discharged by the reduction of the fluid chamber, and a rotational difference sensing device for converting the fluid pressure generated by the outflow restriction by the orifice into the transmission torque between the housing member and the rotor member. In the joint, the sliding portion of the piston with the cam surface is arranged in the axial direction of the rotor member with respect to the central axis of the reciprocating direction of the piston. Rotation difference sensitive coupling being characterized in that disposed offset to shift or the other side. 2. The rotation difference sensitive joint according to claim 1, wherein the offset direction of the sliding portion of the piston located symmetrically with respect to the rotation axis of the rotor member is made different.