JPH01249530A - Vehicle speed and rotation responsive type coupling - Google Patents

Abstract

PURPOSE:To enhance the running ability in low and middle speed ranges, and the steering stability and rectilinearly advancing stability in a high speed range by a vehicle speed responsive type mechanism adapted to open and close in accordance with a rotational speed, in a fluid passage communicating between a plurality of fluid chambers and an accumulator chamber. CONSTITUTION:In a differential gear unit 1, a pair of output gears 15, 16 are meshed with a pinion 12 through the intermediary of a pair of side gears 13, 14 within a differential gear casing 10. In this arrangement, a rotational speed difference responsive type coupling A is disposed between the side gear 14 and the output gear 16, and is provided therein with a cam surface 31 formed on the inner surface of a differential gear casing cover 30, and several cam members 50 formed on the base part 40 of the side gear 14 so as to make slidably contact with the cam surface 31. Further, there are provided several fluid chambers 60 each having a volume which varies in association with the reciprocating motion of each cam member 50, and a fluid passage 70 communicating between the fluid chambers 60 and an accumulator chamber 90. Further, a vehicle speed responsive type mechanism 110 adapted to open and close in accordance with a rotational speed is disposed in the fluid passage 70.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is incorporated into a differential device as a differential limiting means for limiting the differential movement between left and right wheels, or is applicable as a transfer device of a four-wheel drive vehicle. This article relates to a vehicle speed/rotation difference sensitive joint.

(Prior Art) Conventionally, as a differential device incorporating a rotation difference sensitive differential limiting means, a device as described in Japanese Patent Laid-Open No. 61-62642, for example, is known.

The rotational difference sensitive differential limiting means of this differential device is provided on the outer periphery parallel to the output shaft of the differential device, a pair of cams having cam surfaces are provided on the side gears of the pair, and a sleeve between the cams is provided. It is equipped with a pair of plungers that are slidably installed on the shaft, and a fluid chamber that communicates between the plungers through an orifice.When the pair of side gears rotate relative to each other, the pair of plungers exerts a differential limiting force between the left and right wheels. It is designed to generate pressing force.

(Problem to be solved by the invention) However, the rotation difference-sensitive differential limiting means has a structure that exerts the differential limiting function only when the left and right wheels rotate relative to each other due to the rotation difference, and the vehicle speed increases. The differential limiting function was only able to obtain characteristics that were almost unchanged from those at low rotation speeds even when the vehicle was raised, so when driving straight at high speeds such as on expressways where there is almost no difference in rotation between the left and right wheels, the differential limiting function is effective. The problem was that it did not generate any force, making it impossible to improve handling and straight-line stability when driving at high speeds.

(Means for Solving the Problems) The present invention aims to solve the above-mentioned problems, and in order to achieve this purpose, in the present invention, an input/output device is provided between relatively rotatable input/output members. A joint that allows an amount of fluid to flow according to the rotational speed difference of the members, generates fluid pressure by suppressing the flow of this fluid, and controls the transmission torque between the input and output members according to this fluid pressure, a cam surface formed on one side of the input/output member; a cam body supported by the other side of the input/output member, in circumferential contact with the cam surface and reciprocating in a radial direction when the input/output member rotates relative to each other; A fluid chamber with a number of tanks whose volume changes as the cam body reciprocates, a fluid path that communicates between each fluid chamber and the accumulator chamber, and a fluid path that communicates between each fluid chamber and the accumulator chamber. The means is characterized in that it is equipped with a vehicle speed sensitive mechanism that communicates between the fluid passages through a predetermined orifice opening degree and closes the fluid passages by means of a weight that moves outward due to centrifugal force at high rotation speeds.

(Function) When traveling at low to medium speeds, the joint rotates at a low speed, so the vehicle speed sensing mechanism communicates the fluid path and the accumulator chamber through a predetermined orifice opening.

Therefore, when running at low to medium speeds, when there is no rotational speed difference between the input and output members, no fluid pressure or transmission torque is generated, and when there is a rotational speed difference between the input and output members, both Due to the relative rotation of the members, the cam body that is in contact with the cam surface reciprocates in the radial direction, and when the volume of the cylinder chamber is reduced by moving toward the center of the rotation axis during this reciprocating movement, flow resistance due to the orifice opening degree occurs. The pressure inside the cylinder chamber increases, and the resulting hydraulic pressure multiplied by the pressure-receiving area of the cam body becomes a force that presses the cam body against the cam surface. occurs.

When traveling at high speeds, due to the high rotation of the joint,
The vehicle speed sensitive mechanism closes the fluid path by a weight that moves outward due to centrifugal force, and the fluid path and the accumulator chamber are cut off.

Therefore, since the working fluid is confined within the cylinder chamber and fluid path, the pressure inside the cylinder chamber increases rapidly with just a slight inward stroke of the cam body, and then the cam body is pressed against the cam surface with a large force. It is in a locked state and a high transmission torque is generated regardless of the rotational speed difference.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

In this embodiment, as shown in Fig. 1, a vehicle speed/rotation difference sensitive joint A that performs a differential limiting function is built into a differential device 1 that performs a differential function, and both This is an example of a restriction device.

The differential device 1 includes a pinion shaft 11 in a differential case 10 connected to the drive input side.
A pinion 12 rotatably supported via a pinion 12, a pair of side gears 13, 14 meshing with the pinion 12, and two output shafts 15.1 connected to the side gears 13, 14.
6.

Then, one output shaft 1 among the output shafts +5.16
5, the driving force is directly transmitted from the side gear 13, and the driving force is transmitted from the side gear 14 to the other output shaft 16 via the rotation difference sensitive joint A.

As shown in FIGS. 1 and 2, the rotation difference sensitive joint A is connected to the differential case 10 which rotates relatively.
A cam surface 31 formed on the inner surface of the case cover 30 of one differential case 10 and a gear base 40 of the other side gear 14 are provided among the side gears 14, and the cam surface 31 is provided on the gear base 40 of the other side gear 14, and the cam surface 31 contacts the substantially square cam surface 31 due to relative rotation. six radially arranged driving pistons 50 (cam bodies) that reciprocate in the radial direction, six cylinder chambers 60 (fluid chambers) whose volume changes as the driving pistons 50 reciprocate, and each cylinder chamber. A balance oil passage 70 (fluid passage) that communicates between each cylinder chamber 60 and the accumulator chamber 90, and a balance oil passage 70 (fluid passage) provided in the middle of the balance oil passage 70, which is provided between each cylinder chamber 60 and the accumulator chamber 90 when the gear base 40 rotates at low speed. A balance oil passage that communicates via the orifice opening degree and that communicates via a spool valve 110 (vehicle speed sensitive mechanism) that closes the balance oil passage 70 by a weight pole group 113 (weight) that moves outward due to centrifugal force at high speeds. 70 (fluid path), a regulator oil path 80 that communicates between each cylinder chamber 60 and an accumulator chamber 90, and a relief valve 100 that discharges hydraulic oil (fluid) from the accumulator chamber 90 to the outside.

The case cover 30 is integrally bolted to the differential case 10, which is a drive input member.

The gear base 40 is connected to the cam surface 3 of the case cover 30.
1, and the side gear 14 is inserted into the side gear 14.
At the same time, six cylinder holes 42 are formed at equal intervals in the radial direction at positions facing the cam surface 31.

The driving piston 50 is connected to the cylinder hole 4
2, the cam member is provided in an oil-tight state by a seal ring 51, and the circumferential surface with the cam surface 31 is formed into a spherical surface 50a to ensure smooth contact movement, and the radius of curvature of the spherical surface 50a is as follows. The cylinder hole 42 is smaller than the cam surface 31.
It is set larger than the driving pole that matches the diameter of the pole, has a high Hertz contact stress, and can withstand high capacity (high torque).

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

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

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

The accumulator chamber 90 is a chamber that absorbs an increase or decrease in the amount of oil by temporarily storing and releasing hydraulic oil.
an accumulator piston 91 that is provided in an oil-tight manner so as to be able to reciprocate, and the piston 91 and the spring retainer 9.
2 and a spring 93 interposed between the spring 93 and the spring 93.

Incidentally, the accumulator piston 91 is formed with a relief valve 100 that opens a valve hole 101 formed in the gear base 40 when the stroke exceeds a predetermined stroke. I try to let it escape to the outside.

The spool valve 110 is fitted into the valve hole 111 so as to be movable in the axial direction, and includes a spool 112 having a tapered surface 112a formed at one end and an orifice land 112b formed at the other end, and a tapered surface of the spool 112. 11
2a and a return spring 11 provided on the orifice land 112b side of the spool 112.
4.

Incidentally, the spool 112 and the pole case 115 have through holes 112c and 115a in the center, and the valve hole 11
1 and the accumulator chamber 90 are kept in communication.

Next, the operation of the embodiment will be explained.

(a) Low/medium speed When driving at low/medium speed, the spool valve 110 has a return spring 1 that pushes the spool 112 to the right in the drawing.
Since the initial set load of 14 exceeds the centrifugal pushing force of the weight pole group 113 that pushes the subur 112 to the left in the drawing, the balance oil passage 70 as shown in the lower half of Fig. 1
The accumulator chamber 90 and the orifice land 112b
They are in communication via a predetermined orifice opening degree.

Therefore, when driving at low to medium speeds on dry asphalt roads,
When there is no difference in rotational speed between the left and right wheels connected to the output shaft 15, 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 equally distributed to the output shafts 15,16.

In addition, when driving on rough roads or when one wheel gets stuck, the output shaft 15.1
When a difference in rotational speed occurs between the left and right wheels connected to the wheel 6, relative rotation also occurs between the case cover 30 and the gear base 40, and this relative rotation causes the driving piston 50 in circumferential contact with the cam surface 31 to move in the radial direction. When the volume of the cylinder chamber 60 is reduced by moving toward the center of the rotation axis, the pressure inside the cylinder chamber 60 increases due to the flow resistance caused by the orifice land 112b, and this generated hydraulic pressure and the piston 50 is multiplied by the hydraulic pressure or the force that presses the driving piston 50 against the cam surface 31, and this pressing makes the distribution of input drive torque smaller on the high-speed rotation side and larger on the low-speed rotation side. The differential is limited.

It should be noted that the differential limiting torque ΔT shows a torque characteristic drawn by a quadratic function curve, since the greater the rotational speed difference ΔN between the left and right wheels, the greater the pressure difference between the front and rear orifice lands 112b. Since the relief valve 100 is provided to release oil from the accumulator chamber 90 to the outside at a pressure lower than the destructive strength of the drive transmission system, the differential limiting torque is regulated up to a predetermined maximum torque.

As a result of the above, when using a differential, differential restriction control is automatically performed according to the degree of differential, which improves straight-line driving performance on rough roads,
Improves escape performance and tuck-in control when one wheel is stuck.

(b) At high speeds When traveling at high speeds (for example, 80 km/h or more) on expressways, the spool valve 110 moves the spool 112 to the left in the drawing due to the initial set load of the return spring 114 that pushes the spool 112 to the right in the drawing. The centrifugal pushing force of the weight pole group 113 pushing in the direction exceeds the spool 112
Then, the balance oil passage 70 and the accumulator chamber 90 are cut off by the spool 112, as shown in the upper half of FIG.

Therefore, by sealing the hydraulic oil in the cylinder chamber 60 and the balance oil passage 70, the driving piston 5
0 moves slightly inward, cylinder chamber 6
The pressure in 0 increases rapidly, then the driving piston 5
0 is pressed against the cam surface 31 with a large force, resulting in a locked state, and the differential movement 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 at the gear base 40, which rotates at high speed as the output shaft 15, 16 rotates, and this centrifugal force causes the driving piston 50 to move. It will be pressed against the cam surface 31, and a differential limiting force corresponding to this will also be added.

As a result of the above, a high differential limiting force can be obtained at high speeds, which improves steering performance by causing understeer, and also eliminates changes in drive force distribution to the left and right wheels that would cause meandering when one wheel lifts up. , straight-line stability is improved.

For example, if the differential limiting device is configured to provide a high differential limiting force regardless of the vehicle speed, like a differential lock device, the straight-line stability of the vehicle will be extremely improved, but on the other hand, the turning performance will be poor. Become. In particular, at low speeds, there is a marked tendency to understeer, and the steering wheel becomes extremely heavy, making it impractical.

At high speeds, straight-line stability is the first requirement, and on expressways, a tendency to understeer is safer than a tendency to oversteer. However, when the vehicle speed is reduced from the expressway and the vehicle passes through the curved ramp section and enters the public road, this understeer characteristic is not desirable and it is wise to avoid it.

That is, the differential limiting device incorporating the vehicle speed/rotation difference sensitive joint A of the embodiment is based on a rotation difference sensitive differential limiting device, and utilizes centrifugal force that corresponds to the vehicle speed to control the spool. By configuring the valve 110 to operate, it has both a rotation difference-sensitive differential limiting function at low to medium speeds and a vehicle speed-sensitive differential limiting function at high speeds. In addition to achieving the stuck escape effect using the differential limiting device, it is possible to improve straight-line stability during high-speed running.

Furthermore, the target performance can be achieved at an extremely low cost by simply adding the spool valve 110, and the spool valve 170 serves both as an orifice and an opening/closing valve, reducing the number of parts and oil leakage points, making it reliable. It can be made to have high quality.

In addition to the above-mentioned effects, the effects described in the specification of U.S. Pat.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, an example of a preferable spool valve is shown, which also serves as an orifice as a vehicle speed sensing mechanism, has a small number of parts, and has little effect on transmission torque due to oil leakage, or as described in Utility Model Application No. 184485/1985. , an orifice may be formed separately, and the orifice may be combined with a flow path opening/closing valve.

In addition, in the example, an example was shown in which a vehicle speed/rotation difference sensitive joint was incorporated into a differential to be adapted to a differential limiting device.
It may be applied as a transfer device installed at a position where driving force can be distributed to the front and rear wheels of a four-wheel drive vehicle, and in this case as well, the driving force distribution is controlled in the direction of rigid four-wheel drive at high speeds. Straight-line stability can be improved.

(Effects of the Invention) As explained above, the vehicle speed/rotation difference sensitive joint of the present invention is provided between relatively rotatable input and output members, and is adapted to respond to the rotational speed difference between the input and output members. A joint that allows the fluid to flow, generates fluid pressure by suppressing the flow of this fluid, and controls the transmission torque between the input and output members according to this fluid pressure, and communicates between each fluid chamber and the accumulator chamber. The vehicle speed-sensitive system is installed in the middle of the fluid path to communicate between each fluid chamber and the accumulator chamber at low speeds through a predetermined orifice opening, and at high speeds the fluid path is closed by a weight that moves outward due to centrifugal force. Since the method is equipped with a mechanism, it has the effect of improving running performance due to the rotation difference-sensitive transmission torque characteristics when driving at low to medium speeds when the joint is running at low rotations, and it improves the running performance when driving at high speeds when the joint is at high rotations. The effect is that it is possible to simultaneously achieve the effects of improving steering stability and straight-line stability due to the sensitive transmission torque characteristics.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal side view showing a differential limiting device to which a vehicle speed/rotation difference sensitive joint according to an embodiment of the present invention is applied, and Fig. 2 is a longitudinal sectional front view of the differential limiting device taken along line I-I in Fig. 1. It is. A...Vehicle speed/rotation difference sensitive joint 1...Differential device 10...Differential case 11...Binion shaft 12...Binion 13.14...Side gear 15.16...Output Shaft 30... Case cover (input member) 31... Cam surface 40... Gear base C output member) 50... Driving piston (cam body) 60...
Cylinder chamber 70...Balance oil path (fluid path) 90...Accumulator chamber 110...Spool valve (vehicle speed sensitive mechanism) 112.
... Spool 112a ... - Taper surface 112b ... Orifice land 113 ... Weight pole group (weight) 114 ... Return spring

Claims (1)

[Claims] (1) It is provided between relatively rotatable input and output members, allows an amount of fluid to flow according to the rotational speed difference between the input and output members, and generates fluid pressure by suppressing the flow of this fluid, and responds to this fluid pressure. A joint for controlling transmission torque between the input and output members, the joint having a cam surface formed on one of the input and output members, and a joint that is supported by the other of the input and output members and that is in circumferential contact with the cam surface. A cam body that reciprocates in the radial direction when the output member rotates relative to each other, a plurality of fluid chambers whose volume changes as the cam body reciprocates, a fluid path communicating between each fluid chamber and an accumulator chamber, and the fluid A vehicle speed-sensitive mechanism is installed in the middle of the path, and at low speeds, each fluid chamber and the accumulator chamber are communicated through a predetermined orifice opening, and at high speeds, the fluid path is closed by a weight that moves outward due to centrifugal force. A vehicle speed/rotation difference sensitive joint characterized by: