JPH0434102Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a four-wheel drive vehicle (hereinafter referred to as 4WD vehicle) in which the front wheels and rear wheels are connected by a propulsion shaft. This invention relates to a power switching dog clutch that cuts off power transmission when activated.

(Prior Art) A one-way clutch that prevents the braking force of the front wheels from being transmitted to the rear wheels during braking has already been put into practical use.

(Problem to be solved by the invention) As the above-mentioned device, it is possible to install a simple dog clutch that is inexpensive and can be installed on the propulsion shaft from the front wheels to the rear wheels, but in the conventional dog clutch, the meshing surfaces of the dog teeth that mesh with each other are Since the surface was parallel to the axial direction, a very high operating force sufficient to overcome the meshing force of the dog teeth was required to interrupt the power transmission.

Therefore, the purpose of this invention is to use the deceleration force that acts on the propulsion shaft when the brake is activated during transmission of forward driving force to easily interrupt the operation with a low operating force, and to create a tolerance rotation speed that allows both dog teeth to engage. The purpose of the present invention is to provide a dog clutch for power switching that can be used for power switching.

(Means for Solving the Problems) In order to solve the above problems and achieve the purpose, the present invention provides a power switching dog clutch 10 that cuts off power transmission when the brake is applied to the propulsion shaft that connects the front wheels and the rear wheels. In a 4WD vehicle equipped with a dog piece 4 fixed to one of the input/output shafts 1 and 2, a hub 5 provided on the other side so as to be slidable in the axial direction, and the sliding of the hub 5 in the axial direction restricted. or an electric actuator 97 for releasing, and one side surface on the rotation transmission side and the opposite side thereof when forward driving force is transmitted between the dog teeth 42..., 52... provided on the dog piece 4 and the hub 5 respectively and meshing with each other. The other side surface is formed into a tapered surface with an angle that intersects the axis, and the angle of intersection with the axis of the tapered surface on the rotation transmission side is the angle of intersection with the axis of the tapered surface on the opposite side to the rotation transmission side. It is characterized by being equipped with a power switching dog clutch 10 formed smaller.

(Function) During transmission of forward driving force, the dog teeth 42..., 52 provided on the dog piece 4 and the hub 5, respectively.
Since the other side surface opposite to the rotation transmission side in ... is a tapered surface 43..., 53..., the meshing with the dog tooth tapered surface 43... of the fixed dog piece 4 is caused by the deceleration force during brake operation. The dog tooth tapered surfaces 53 of the hub 5 receive the thrust force, and the hub 5 is urged in a direction away from the dog piece 4.

When such a brake is activated, each dog tooth taper surface 43
Since the hub 5 can be moved using the thrust force generated between ..., 53..., the electric actuator 97
The dog clutch 10 can be easily disconnected with a low operating force.

The rotation transmission side of both dog teeth 42..., 52... is also made into a tapered surface 44..., 54, and this tapered surface 44
..., 54... is made smaller than the taper angle θ ₂ that intersects with the axis of the other tapered surface 43..., 53... _, so both dog teeth 42
. . , 52 . . . can be engaged with each other by increasing the rotational speed tolerance.

(Example) Examples will be described below based on the accompanying drawings.

In Figure 1, 1 is the input shaft, 2 is the output shaft, and 3 is the input shaft.
is a clutch case, and a flange joint 32 is fixed with a nut 12 by engaging splines 11 and 33 on the front outer periphery of the input shaft 1, which is positioned at the front of the clutch case 3 with a bearing 31. The outer periphery of the front end of the output shaft 2, which is positioned at the rear by a bearing 34, is fitted into the circular recess 13 at the rear of the input shaft 1 via a bearing 35 so as to be relatively rotatable.

Here, as shown in FIG. 9, the rotational driving force from the engine 101 is input to the differential device 103 of the front wheel drive system 102, and a propulsion shaft 104 that extends rearward from the engine 101 and transmits the rotational driving force is connected. The input shaft 1 is connected to the input shaft 1 by a flange joint 32, and the output shaft 2 is connected to a differential device 106 using a viscous coupling spring of a rear wheel drive system 105 at the rear, and the input shaft 1 constitutes a propulsion shaft in such a 4WD vehicle.
A power switching dog clutch 10 according to the present invention is disposed between the output shaft 2 and the output shaft 2.

As shown in FIG. 1, the dog clutch 10 consists of a dog piece 4, a hub 5, a ball 6, a sleeve 8, etc.
The dog piece 4 is fitted with splines 21 and 41 on the front outer periphery of the output shaft 2 in the clutch case 3 and fixed with a nut 22, and the hub 5 is fixed with a nut 22 on the front outer periphery of the input shaft 1 in the clutch case 3. 15 and 51 are fitted together and can freely slide in the axial direction, and the rotation direction is provided integrally with the shaft. On both opposing surfaces of the dog piece 4 and the hub 5, there are a large number of dog teeth 42..., 52... that protrude in the axial direction and can freely engage with each other.
are provided at equal intervals in the circumferential direction, and the dog teeth 42, 52 are arranged as shown in FIG.
The side surface opposite to the rotation transmission side is formed into a tapered surface 43, 53 that intersects the axis at a relatively large angle, and the side surface on the rotation transmission side also has a tapered surface that intersects the axis at a slightly small angle. 44, 54.

In particular, during the transmission of forward driving force in the direction of arrow F due to the engagement of each tapered surface 44..., 54... on the rotation transmission side, braking is performed by distributing the brakes stronger on the front wheels than on the rear wheels in order to ensure stability. As a result of the brake distribution, a decelerating force is first applied to the input shaft 1 side in the direction of arrow B, which is opposite to the rotational direction F, so that each of the tapered surfaces 43..., 53... on the side opposite to the rotation transmission side meshes with each other. Therefore, due to the engagement of each tapered surface 43..., 53..., the hub 5
A moving force is generated in the thrust direction.

Below, the tapered surface 43 on the side opposite to the rotation transmission side,
53 is called a deceleration side tapered surface, and conversely, the rotation transmission side tapered surfaces 44 and 54 are called acceleration side tapered surfaces.

The front part of the hub 5 is formed into a small diameter part 55 and extends slidably onto the outer circumference of the intermediate part of the input shaft 1, and the rear part of the small diameter part 55 has, for example, three guides arranged at equal intervals in the circumferential direction. Holes 56 are formed through the holes 56 radially, and similar guide holes 57 are formed through the front part of the small diameter portion 55, and the balls 6, 7, . are stored in each. Furthermore, an annular engagement groove 16 into which the rear balls 6 are pushed is formed in a portion of the outer periphery of the intermediate portion of the input shaft 1 that is continuous with the front end of the spline 15.

Furthermore, a sleeve 8 is provided on the outer circumferential side of the small diameter portion 55 of the hub 5.
is arranged to be slidable in the axial direction, and each of the rear balls 6 can be freely pushed into the engagement groove 16 on the outer periphery of the input shaft 1 on the inner periphery of the rear intermediate portion of the sleeve 8.
An annular protrusion 8 that is slidable on the outer periphery of the small diameter portion 55
6 is formed. Further, the inner periphery of the front part of the sleeve 8 serves as a guide surface 87 that comes into sliding contact with each of the front balls 7 rolling on the outer periphery of the intermediate part of the input shaft 1.
When the sleeve 8 moves forward, the rear inner periphery also serves as a guide surface 88 for each of the balls 6 at the rear.

On the other hand, the clutch case 3 is provided with an operating device 9 for the dog clutch 10 described above. That is, a shift fork 91 equipped with bifurcated fork claws 92, 92 that engage with an annular groove 82 provided on the outer periphery of the sleeve 8 is connected to a shift rod 94 by a spring pin 93.
The shift rod 94 is slidably installed in the clutch case 3 in the axial direction parallel to the input/output shafts 1 and 2 arranged on the same axis.
Also, a return spring 9 is provided on the outer periphery of the shift rod 94 between the front part inside the clutch case 3 and the shift fork 91 to bias the dog clutch 10 in the connection direction.
5 is compressed, and a connecting pin 96 is attached to the front end of the shift rod 94 that protrudes forward from the clutch case 3.
A movable portion 98 of a solenoid 97, which is an electric actuator, is coupled at.

When the solenoid 97 is energized in conjunction with the brake operation, the magnetic force causes the movable portion 98 to move the shift rod 94 forward from the illustrated state against the bias of the return spring 95 through the connecting pin 96. The sleeve 8 is moved forward from the illustrated state via the shift fork 91.
Further, when the power to the solenoid 97 is cut off, the operating device 9 and the sleeve 8 are returned to the illustrated state by the bias of the return spring 95.

In the above, during the power transmission from the input shaft 1 to the output shaft 2 by the connection of the dog clutch 10 as shown in the figure, especially as shown in FIG.
4..., 54... while forward driving force is being transmitted in the direction of arrow F due to the engagement of the solenoid 97 and the return spring 9.
When the sleeve 8 is moved forward through the shift rod 94 and the shift fork 91 against the bias of the input shaft 1, the protrusion 86 on the inner circumference of the sleeve 8 engages the rear balls 6 on the outer circumference of the input shaft 1. The push into the groove 16 is released.

As mentioned above, braking is done by distributing the brakes so that the front wheels are stronger than the rear wheels in order to ensure stability, and as a result, a decelerating force is applied to the input shaft 1 side in the direction of arrow B, opposite to the rotational direction F. As a result, the reduction side tapered surfaces 43..., 53... of the dog teeth 42... of the dog piece 4 fixed on the output shaft 2 and the splines 15, 53... on the input shaft 1 engage with each other. 51, the engaged dog teeth 52 of the hub 5 are engaged with the deceleration side tapered surfaces 53, and a thrust force is applied during rotation, so the balls 6 are disengaged from the engagement grooves 16 due to the thrust force. At the same time as the sleeve 8 protrudes into the guide surface 88 on the rear inner circumference, the hub 5 moves forward on the input shaft 1 and the dog teeth 42..., 52... are disengaged.

Moreover, if the power to the solenoid 97 is cut off, the operating device 9 is biased by the return spring 95.
The sleeve 8 then returns to the state shown, and the dog clutch 10 is connected.

In this way, the dog clutch 10 of the present invention is configured such that when the brake is applied during transmission of forward drive torque, each deceleration side tapered surface of both dog teeth 42..., 52... is generated by the deceleration force acting on the input shaft 1 on the forward drive system 102 side. By utilizing the thrust force generated by the meshing of 43..., 53..., torque is transmitted from the input shaft 1 to the output shaft 2 with a low operating force that is enough to move the sleeve 8 that restricts the movement of the balls 6... can be blocked.

Therefore, when a four-wheel anti-lock brake is combined with the four-wheel drive vehicle shown in FIG. Wheel antilock brakes can be operated effectively. It is also effective in ensuring stable vehicle behavior when used in combination with regular brakes.

Note that the dog piece 4 may be arranged on the input shaft 1 and the hub 5 may be arranged on the output shaft 2.

Next, using a theoretical calculation formula, it will be analyzed that the dog clutch 10 of the present invention can be switched with a low operating force, especially during deceleration.

In Fig. 3, Fa ₁ is the thrust force generated by the meshing of the dog teeth 42, 52, Fa ₂ is the axial frictional resistance due to the engagement of the splines 15, 51 between the input shaft 1 and the hub 5, and Fa is the frictional resistance in the axial direction due to the engagement of the splines 15, 51 between the input shaft 1 and the hub 5. The force pushing the ball 6, T is the transmitted torque, _r1 is the rotation radius of the dog teeth 42, 52, _r2 is the rotation radius of the splines 15, 51, and can be expressed as Fa= _Fa1 - _Fa2 .

Here, as shown in FIG.
When the taper angles θ ₁ and θ 2 of the tapered surfaces 4 and 54 and the tapered surfaces 43 and ₅₃ on the deceleration side are the same angle (θ ₁ = θ ₂ ), Fa>0, but in the present invention, as shown in FIG. The taper angle θ ₁ of the acceleration side taper surfaces 44 and 54 is the deceleration side taper surface 4.
It is set to be smaller than the taper angle θ ₂ of 3.53, and Fa<0.

That is, when the friction coefficient of the tooth surfaces of the dog teeth 42 and 52 is μ ₁ , Fa ₁ =T/r ₁ tanθ ₁ − _{μ 1} ·T/r ₁ is obtained.

Further, if the pressure angle of the splines 15, 51 is α and the friction coefficient of the tooth surface is μ ₂ , then Fa ₂ =T/r ₂ ·μ ₂ /cosα is obtained.

In power transmission in the acceleration direction F, since Fa<0, Fa=Fa ₁ −Fa ₂ <0 Fa ₁ <Fa ₂ T/r ₁ tanθ ₁ −μ ₁・T/r ₁ <T/r ₂・θ ₁ may be set so that μ ₂ /cosα ∴θ ₁ <tan ⁻¹ r ₁ μ ₂ /r ₂ cosα+μ ₁ .

Next, the increase in the allowable rotational speed that can be engaged by the dog crunch 10 of the present invention will be explained.

First, due to the structure of the dog clutch 10 of the present invention, in power transmission in the acceleration direction F, since Fa<0, the acceleration side tapered surfaces 44..., 54... as shown in FIG. Even when the hub 5 does not completely enter the engagement groove 16 of the input shaft 1, the hub 5 can maintain the state shown in FIG.

Here, in the case of Fa>0, the torque will not be increased unless the ball 6 completely enters the input shaft engaging groove 16 as shown in FIG. Transmission is not possible, and as a result, the hub 5 is moved backward by the force of the thrust Fa. In particular, when the differential rotation between the hub 5 and the dog piece 4 is large, the relative speed between the hub 5 and the dog piece 4 is high, so the above-mentioned operation occurs continuously accompanied by abnormal noise.

On the other hand, if Fa<0, the rotation difference between the hub 5 and the dog piece 4 is set to 0 in the incomplete meshing state shown in FIG. The inner peripheral protrusion 86 of the sleeve passes over the center of the ball 6, and the shift is completed.

Therefore, by setting the dog tooth taper angle such that Fa<0 than Fa>0, the sleeve 8 can be engaged.
The stroke can be reduced and the tolerance rotation speed can be increased.

Further, the stroke of the sleeve 8 can also be reduced by reducing the diameter of the ball 6.

In other words, when Fa > 0, the value of Fa, that is, the load applied to the ball 6 increases due to the increase in the transmitted torque T. However, in the present invention, in the acceleration direction F, Fa <
0, no load is applied to the ball 6. Therefore, a load is applied to the ball 6 only when torque is transmitted in the deceleration direction B. Since the deceleration torque is smaller than the acceleration torque, the forced restriction of the ball 6 is halved. Therefore, the diameter of the ball 6 can be reduced.

The reduction in the stroke of the sleeve 8 due to the reduction in the diameter of the ball 6 will be demonstrated below using a theoretical calculation formula.

In FIG. 8, Ds is the sleeve inner peripheral protrusion 86
The diameter of D ₁ is the diameter of the ball 6 and the inner protrusion 86 of the sleeve.
The diameter of point P, which is the contact part with the side surface, X is the axial distance from the center of ball 6 shown by the broken line in 4WD to point P, D ₂ is the diameter of input shaft 1, a is the center of ball 6 in 4WD of the axial distance from to the end of the sleeve inner peripheral protrusion 86, r is the radius of the ball 6, θ
is the inclination angle of the side surface of the sleeve inner peripheral protrusion 86.

In such FIG. 8, the ball 6 and the sleeve 8
When the relative position of hub 5 shifts from the broken line to the solid line,
can be slid in the axial direction. At this time, the ball 6 comes into contact with the inclined surface point P on the side surface of the sleeve inner peripheral protrusion 86. Sleeve stroke to reach this state
Find Ls.

D ₁ = D ₂ + 2r + 2rsin θ = D ₂ + 2r ( ₁ + sin θ) ... X = a + D ₁ - Ds / 2 tan θ ... and Ls = Ls=a+{D ₂ +2r(1+sinθ)+Ds}×tanθ/2+rcosθ is obtained.

Therefore, when r is made smaller, Ls becomes smaller.

(Effect of the invention) As described above, according to the power switching dog clutch for a 4WD vehicle according to the present invention, during forward driving force transmission, the dog teeth provided on the dog piece and the hub, on the opposite side to the rotation transmission side, Since the side surface is tapered, the hub's dog tooth taper receives the thrust force caused by the engagement with the dog tooth taper surface of the fixed dog piece due to the deceleration force acting on the propulsion shaft when the brake is applied, and the hub Since the hub is biased in the direction away from the dog piece, in other words, the hub can be moved using the thrust force generated between the tapered surfaces of each dog tooth when the brake is applied, so the dog clutch can be easily moved with a low operating force from the electric actuator. Can be blocked.

In the present invention, the rotation transmission side of both dog teeth is also a tapered surface, and the taper angle that intersects the axis of this tapered surface is smaller than the taper angle that intersects the axis of the other tapered surface. It is possible to increase the tolerance rotation speed that allows for meshing.

As described above, according to the present invention, in particular, by increasing the intersection angle between the rotation transmission side of both dog teeth and the axis of the tapered surface on the opposite side, it is possible to easily disconnect the dog clutch during braking of a 4WD vehicle. In addition, by providing an electric actuator that restricts or cancels the sliding of the hub in the axial direction, the clutch can be controlled, and the hub can be slid only by the driving force of the electric actuator. The clutch itself can be manufactured compactly compared to the conventional clutch.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the dog clutch portion according to the present invention, Fig. 2 is a developed view showing the meshing of both dog teeth,
Figure 3 is a schematic diagram showing the specifications of the relationship between the shaft, hub, ball, and sleeve for theoretical analysis, and Figure 4 is a dog tooth meshing state with both acceleration and deceleration side surfaces tapered at the same angle. Fig. 5 is a schematic diagram of the dog tooth meshing state with a large angle of the tapered surface on the deceleration side according to the present invention, Fig. 6 is a schematic diagram of the dog tooth half meshing state, and Fig. 7 is a schematic diagram of the same ball. FIG. 8 is a schematic diagram showing specifications for further theoretical analysis, and FIG. 9 is a schematic diagram of the 4WD vehicle. In the drawings, 1 is an input shaft, 2 is an output shaft, 4 is a dog piece, 42 is a dog tooth, 43 is a tapered surface on the deceleration side, 44 is a tapered surface on the acceleration side, 5 is a hub, 52 is a dog tooth, and 53 is a deceleration 54 is an acceleration side tapered surface, 10 is a dog clutch, and 97 is an electric actuator.

Claims (1)

[Scope of Claim for Utility Model Registration] A four-wheel drive vehicle in which a power switching dog clutch is interposed on the propulsion shaft connecting the front wheels and the rear wheels to cut off power transmission when the brake is applied, the dog clutch being one of the input and output shafts. A dog piece fixed to the dog piece, a hub slidably provided on the other hand in the axial direction, and an electric actuator for regulating or canceling the sliding of the hub in the axial direction, and the dog piece and the hub are each provided with One side surface on the rotation transmission side and the other side surface on the opposite side when transmitting the forward driving force of both meshing dog teeth are both formed into tapered surfaces with an angle intersecting the axis, and the tapered surface on the rotation transmission side is formed. A dog clutch for power switching of a four-wheel drive vehicle, in which the angle of intersection with the axis is smaller than the angle of intersection with the axis of the tapered surface on the opposite side to the rotation transmission side.