JPH0773983B2 - Vehicle speed / speed difference sensitive joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is incorporated in a differential device as differential limiting means for limiting the differential between the left and right wheels, or is applied as a transfer device for a four-wheel drive vehicle. The present invention relates to a vehicle speed / rotational difference sensitive joint.

(Prior Art) Conventionally, as a differential device incorporating a rotation difference sensitive differential limiting means, for example, a device described in JP-A-61-62642 is known.

The rotation difference sensitive type differential limiting means of the differential device is provided on an outer peripheral portion parallel to the output shaft of the differential device, a pair of cams having cam surfaces is provided on a pair of side gears, and a sleeve between the cams is provided. Equipped with a pair of slidable plungers and a fluid chamber that communicates between the plungers via an orifice.When the pair of side gears rotate relative to each other, the pair of plungers are pressed against each other as a left and right differential limiting force. I try to generate power.

(Problems to be Solved by the Invention) However, in the rotation difference sensitive differential limiting means, the differential limiting function is exerted only when the left and right wheels relatively rotate due to the rotation difference, and the vehicle speed is Even if it goes up, the differential limiting function can obtain only the characteristic that it is almost the same as that at low speed, so the differential limiting function can be used when driving straight at high speed on highways where there is almost no difference in rotation between the left and right wheels. There was a problem that power was not generated and it was not possible to expect improvement in steering stability and straight running stability at high speeds.

(Means for Solving the Problems) The present invention aims to solve the above-mentioned problems, and in order to achieve this object, the present invention provides an input / output member provided between relatively rotatable input / output members. A joint for flowing an amount of fluid according to a difference in rotational speed between members, generating a fluid pressure by suppressing the flow of the fluid, and controlling a transmission torque between the input / output members according to the fluid pressure. A cam surface biased to one of the input / output members, and a cam body supported by the other of the input / output members and reciprocally moving in a radial direction when the input / output members rotate relative to each other and are in circumferential contact with the cam surfaces. A plurality of fluid chambers whose volumes change with the reciprocating movement of the cam body, a fluid passage that communicates between each fluid chamber and an accumulator chamber through a predetermined orifice opening, and a fluid passage at an axial position that communicates with the accumulator. Spoo provided in A return spring provided on one end side of the spool, and a weight provided on the other end side of the spool, and the biasing force of the return spring is applied to the spool in a direction to open a fluid path. A vehicle speed responsive mechanism that converts a centrifugal force generated in the weight by rotation into an axial force and applies the axial force to the spool in a direction of closing a fluid path. And

(Operation) When traveling at low / medium speed, due to the low rotation of the joint, the centrifugal force generated in the weight of the vehicle speed sensitive mechanism is small, and the biasing force of the return spring acting on the spool exceeds the axial force of the weight. The position of the spool is regulated by the urging force acting in the direction of opening the fluid passage. Therefore, the fluid path at the axial center position that communicates with the accumulator remains open, and a plurality of fluid chambers that change in volume due to the reciprocating movement of the cam body and the accumulator chamber are provided through a fluid passage having a predetermined orifice opening. It will be in a state of communication.

Therefore, at low / medium speed running, when there is no difference in rotational speed between the input and output members, neither fluid pressure nor transmission torque is generated. On the other hand, when a rotational speed difference occurs between the input and output members,
The cam body circumferentially contacting the cam surface by the relative rotation of both members reciprocates in the radial direction, and when it is attempted to reduce the volume of the cylinder chamber by moving toward the center of the rotation axis in this reciprocation,
The pressure in the cylinder chamber rises due to the flow resistance due to the orifice opening, and the hydraulic pressure that is generated by multiplying this generated hydraulic pressure with the pressure receiving area of the cam body becomes the force that presses the cam body against the cam surface. Transfer torque is generated.

When traveling at high speed, due to the high rotation of the joint,
The centrifugal force generated in the weight of the vehicle speed sensitive mechanism is large, the axial force of the weight exceeds the biasing force of the return spring that acts on the spool, and the spool position is regulated by the axial force acting in the direction to close the fluid path. It Therefore, the fluid path at the axial center that communicates with the accumulator is closed by the spool, and there is no fluid flow between the plurality of fluid chambers and the accumulator chamber that change in volume due to the reciprocating movement of the cam body.

Therefore, by confining the working fluid in the cylinder chamber and the fluid passage, the pressure in the cylinder chamber suddenly increases only by a slight stroke of the cam body, and then the cam body is pressed against the cam surface with a large force. The locked state occurs, and high transmission torque is generated regardless of the rotational speed difference.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings. First, the configuration of the embodiment will be described.

In the embodiment, as shown in FIG. 1, a vehicle speed / rotational difference sensitive joint A having a differential limiting function is incorporated in a differential device 1 having a differential function, and a differential is provided between the two. It is an example which constituted the limiting device.

The differential device 1 includes a pinion 12 rotatably supported via a pinion shaft 11 in a differential case 10 connected to a drive input side, and the pinion 12.
A pair of side gears 13, 14 that mesh with the side gears 13, 14
And two output shafts 15 and 16 connected to.

Then, the driving force is directly transmitted from the side gear 13 to one of the output shafts 15 and 16, and the other output shaft 15 is transmitted.
Driving force is transmitted to the side gear 14 from the side gear 14 via the rotation difference sensitive joint A.

As shown in FIGS. 1 and 2, the rotation-sensitive joint A has one of the differential case 10 and the side gear 14 that rotate relative to each other.
The cam surface 31 formed on the inner surface of the case cover 30 of 10 and the gear base 40 of the other side gear 14 are provided in a radial arrangement that reciprocates in the radial direction while making circular contact with the substantially square cam surface 31 by relative rotation. 6 driving pistons 50
(Cam body), six cylinder chambers 60 (fluid chambers) whose volume changes with the reciprocating movement of the driving piston 50, and a balance oil passage 70 (fluid passage) communicating between each cylinder chamber 60 and the accumulator chamber 90. And is provided in the middle of the balance oil passage 70, and when the gear base 40 is in low rotation, each cylinder chamber
A spool valve 110 (vehicle speed sensitive mechanism) that communicates between the 60 and the accumulator chamber 90 through a predetermined orifice opening, and closes the balance oil passage 70 by a weight ball group 113 (weight) that moves outward due to centrifugal force during high rotation. ), A regulator oil passage 80 that communicates between each cylinder chamber 60 and the accumulator chamber 90, and a relief valve 100 that discharges hydraulic fluid (fluid) from the accumulator chamber 90 to the outside.

The case cover 30 is integrally provided with the differential case 10, which is a drive input member, by bolting.

The gear base 40 is disposed in the cam surface 31 of the case cover 30 in an inserted state, forms the side gear 14, and is spaced at equal intervals in the radial direction at a position facing the cam surface 31. A cylinder hole 42 is formed at the position.

The driving piston 50 is a cam member provided in an oil-tight state by a seal ring 51 with respect to the cylinder hole 42, and a circumferential contact surface with the cam surface 31 is formed into a spherical surface 50a to ensure smooth contact movement. The radius of curvature of the spherical surface 50a is set to be smaller than that of the cam surface 31 but larger than that of the driving ball that fits the diameter of the cylinder hole 42, so that the contact stress of Hertz is high and it can withstand a high capacity (high torque). ing.

The cylinder chamber 60 is a chamber formed between the cylinder hole 42 and the driving piston 50, and its volume changes as the driving piston 50 reciprocates.

The balance oil passage 70 is formed radially from the valve hole 111 of the spool valve 110 formed in the gear base 40.

The regulator oil passage 80 is formed radially from the valve hole 111 of the spool valve 110 formed in the gear base 40, and a ball valve that allows only the flow of hydraulic oil from the accumulator chamber 100 to the cylinder chamber 60 in the middle thereof. A one-way valve 81 having a structure is provided.

The accumulator chamber 90 is a chamber for temporarily increasing and decreasing the amount of oil by temporarily storing and releasing hydraulic oil, and an accumulator piston 91 provided in a gear base portion 40 in an oil-tight state so that it can reciprocate, and the piston 91 and a spring. And a spring 93 interposed between the retainer 92 and the retainer 92.

Incidentally, the accumulator piston 91 is provided with a relief valve 100 that opens a valve hole 101 opened in the gear base 40 when the stroke exceeds a predetermined stroke, and when the accumulator chamber 90 exceeds a set pressure, operating oil is released. I try to let it escape to the outside.

The spool valve 110 is fitted in the valve hole 111 so as to be movable in the axial direction, and has a tapered surface 112a formed at one end and an orifice land 112b formed at the other end.
And a weight ball group 113 housed in a ball case 115 in contact with the tapered surface 112a of the spool 112, and a return spring 114 provided on the orifice land 112b side of the spool 112.

In addition, through holes 112c and 115a are opened in the center of the spool 112 and the ball case 115 so that the valve hole 111 and the accumulator chamber 90 are kept in communication with each other.

Next, the operation of the embodiment will be described.

(A) At low / medium speed When traveling at low / medium speed, the spool valve 110 pushes the spool 112 to the right in the drawing. The initial set load of the return spring 114 causes the spool 112 to push the spool 112 to the left in the drawing. Since the centrifugal pressing force of 113 is exceeded, as shown in the lower half of FIG. 1, the balance oil passage 70 and the accumulator chamber 90 are in communication with each other through a predetermined orifice opening by the orifice land 112b. There is.

Therefore, when driving at low or medium speeds on dry asphalt roads,
When there is no difference in rotational speed between the left and right wheels connected to the output shafts 15 and 16, there is no relative rotation between the case cover 30 and the rotor 40, and the driving piston 50 does not reciprocate in the radial direction. The input engine driving force is evenly distributed to the output shafts 15 and 16.

Further, when a difference in rotational speed occurs between the left and right wheels connected to the output shafts 15 and 16 when traveling on a rough road or when one wheel is stacked, relative rotation also occurs between the case cover 30 and the gear base 40, The driving piston that makes circumferential contact with the cam surface 31 by this relative rotation
50 reciprocates in the radial direction, and when it is attempted to reduce the volume of the cylinder chamber 60 by moving toward the center of the rotation axis in this reciprocation, the pressure in the cylinder chamber 60 increases due to the flow resistance by the orifice land 112b. , This generated oil pressure and piston
The hydraulic pressure multiplied by the pressure receiving area of 50 becomes the force that presses the driving piston 50 against the cam surface 31, and this pressing force differentially distributes the input drive torque so that the high-speed rotation side is reduced and the low-speed rotation side is increased. Is limited.

Note that the differential limiting torque ΔT exhibits a torque characteristic represented by a quadratic function curve because the larger the rotational speed difference ΔN between the left and right wheels is, the larger the pressure difference across the orifice land 112b becomes. Since the relief valve 100 that releases the oil from the accumulator chamber 90 to the outside with a pressure smaller than the breaking strength of the transmission system is provided, the differential limiting torque is specified up to a predetermined maximum torque.

Due to the above, the differential limit control is automatically performed according to the degree of differential during differential operation, which leads to straight running performance on rough roads,
Improves escapeability and tuck-in control when one wheel is stacked.

(B) At high speed When traveling on a highway at a high speed (for example, 80 km / h or more), the spool valve 110 pushes the spool 112 to the right in the drawing. The centrifugal pushing force of the weight ball group 113 pushing in the direction increases, and the spool 112 strokes to the left in the drawing, and as shown in the upper half of FIG.
Then, the accumulator chamber 90 is shut off by the spool 112.

Therefore, by confining the hydraulic oil in the cylinder chamber 60 and the balance oil passage 70, the pressure in the cylinder chamber 60 suddenly increases with only a slight stroke of the driving piston 50, and then the driving piston 50 moves to the cam surface.
It is pressed against 31 with a large force to be in a locked state, and the differential between the left and right wheels is limited by a very large differential limiting force.

When traveling at high speed, centrifugal force acts on the driving piston 50 provided on the gear base 40 that rotates at high speed with the rotation of the output shafts 15 and 16, and this driving force causes the driving piston 50 to cam. Since it is pressed against the surface 31, the differential limiting force is also added.

Due to the above, at high speeds, a high differential limiting force is obtained, so steering performance is understeer, which improves maneuverability, and there is no change in the distribution of driving force to the left and right wheels that causes meandering even when one wheel floats up. , Straight ahead stability is improved.

Here, for example, if the differential limiting device is made to obtain a high differential limiting force regardless of the vehicle speed like the diff lock device, the straight running stability of the vehicle is extremely improved, but the turning performance is worse. Become. In particular, at low speeds, the understeer tendency becomes remarkable, and the handle becomes extremely heavy, which cannot be practical.

When traveling at high speeds, straight running stability is the first requirement, and on an expressway, a little understeer tendency is more safe than an oversteer tendency. However, if the vehicle speed is reduced from the highway and the ramp section curved road is entered into the general road, this understeer characteristic is not desirable and it is advisable to avoid it.

That is, in the differential limiting device incorporating the vehicle speed / rotational difference sensitive joint A of the embodiment, the spool is formed by utilizing the centrifugal force which has a corresponding relationship with the vehicle speed, based on the differential speed sensitive differential limitation. By configuring the valve 110 to operate,
In addition to having both the rotation speed sensitive differential limiting function at medium speed running and the vehicle speed sensitive differential limiting function at high speed, achieving the stack escape effect etc. by the rotation differential sensitive differential limiting device. Thus, it is possible to improve straight running stability when traveling at high speed.

Moreover, the target performance can be achieved at an extremely low cost by simply adding the spool valve 110, and the spool valve 110 that doubles as an orifice and an on-off valve is used, and the number of parts and oil leakage points are reduced, which is reliable. It is possible to make it high.

In addition to the above effects, the effects described in the specification of Japanese Utility Model Application No. 62-184485 previously filed by the present applicant can be obtained.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention can be applied even if there is a design change or the like within a range not departing from the gist of the present invention. included.

For example, in the embodiment, an example of a preferable spool valve having a small number of parts and a small effect of transmission torque due to oil leakage is shown, which is also described in Japanese Patent Application No. 62-184485. Alternatively, an orifice may be separately formed, and the orifice may be combined with a passage opening / closing valve.

Further, in the embodiment, the example in which the vehicle speed / rotational difference sensitive joint is incorporated in the differential device to adapt to the differential limiting device has been shown.
A transfer device provided at a position where the driving force can be distributed to the front and rear wheels of a four-wheel drive vehicle may be adapted, and in this case also, the driving force distribution should be controlled in the rigid four-wheel drive direction at high speed. Thus, it is possible to improve straight running stability.

(Effects of the Invention) As described above, in the vehicle speed / rotational difference sensitive joint of the present invention, the vehicle-speed / rotational-difference sensitive joint is provided between the relatively rotatable input / output members and has an amount corresponding to the rotational speed difference of the input / output members. A joint for flowing a fluid, generating a fluid pressure by suppressing the flow of the fluid, and controlling a transfer torque between the input / output members according to the fluid pressure, the joint being formed on one of the input / output members. A cam body that is supported by the other of the input / output member and that reciprocates in the radial direction when the input / output member makes relative contact with the cam surface, and the volume changes with the reciprocating movement of the cam body. A plurality of fluid chambers, a fluid passage communicating between each fluid chamber and the accumulator chamber via a predetermined orifice opening, a spool provided in the fluid passage at an axial center position communicating with the accumulator, and one end of the spool Rita provided on the side A return spring and a weight provided on the other end side of the spool, and the biasing force of the return spring acts on the spool in a direction to open a fluid path,
Since the centrifugal force generated in the weight due to the rotation is converted into an axial force and the axial force acts on the spool in the direction of closing the fluid passage, a means for providing a joint is provided. The effect of improving the drivability due to the rotation difference sensitive transmission torque characteristic at low and medium speed running at low rotation, and the stability and straight running stability by the high vehicle speed sensitive transmission torque characteristic at high speed running at high joint speed. The effect that it is possible to achieve compatibility with the effect of improving the property is obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a differential limiting device to which a vehicle speed / rotational difference sensitive joint of an embodiment of the present invention is applied, and FIG. 2 is a vertical sectional front view of the differential limiting device taken along the line I-I in FIG. Is. A …… Vehicle speed / rotation difference sensitive joint 1 …… Differential device 10 …… Differential case 11 …… Pinion shaft 12 …… Pinion 13,14 …… Side gear 15,16 …… Output shaft 30 …… Case cover (input 31) Cam surface 40 ... Gear base (output member) 50 ... Driving piston (cam body) 60 ... Cylinder chamber 70 ... Balance oil passage (fluid passage) 90 ... Accumulator chamber 110 ... Spool valve (Vehicle speed sensitive mechanism) 112 …… Spool 112a …… Tapered surface 112b …… Orifice land 113 …… Weight ball group (weight) 114 …… Return spring

Claims (1)

[Claims] 1. A device provided between input / output members capable of relative rotation,
Flowing an amount of fluid according to the rotational speed difference of the input / output member, and generating fluid pressure by suppressing the flow of this fluid,
A joint for controlling a transmission torque between the input / output members according to the fluid pressure, the cam surface being formed on one of the input / output members, and being supported by the other of the input / output members, the cam A cam body that makes circumferential contact with the surface and reciprocates in the radial direction when the input / output member relatively rotates, a plurality of fluid chambers that change in volume due to the reciprocating motion of the cam body, and a predetermined orifice opening between each fluid chamber and the accumulator chamber. Fluid passage communicating with the accumulator, a spool provided in the fluid passage at an axial position communicating with the accumulator, a return spring provided at one end of the spool, and a return spring provided at the other end of the spool. The return spring applies an urging force to the spool in a direction to open the fluid path, and converts the centrifugal force generated in the weight by the rotation into an axial force. Speed-rotation difference sensitive coupling, characterized in that it comprises a and a vehicle speed sensitive mechanism which acts in a direction to close the fluid path to the spool.