JPH01120443A - Four-wheel-drive coupling device - Google Patents

Abstract

PURPOSE:To reduce the size of a hydraulic pump by arranging a clutch and a pressure responsive member coaxially while facing each other, then arranging a diaphragm type spring between the clutch and the pressure responsive member and contacting the intermediate section thereof with the clutch. CONSTITUTION:Upon occurrence of relative rotation between a drive shaft 1 and a driven shaft 2, a hydraulic pump 8 is driven to produce hydraulic pressure which causes movement of the body (pressure responsive member) of the hydraulic pump 8 toward a clutch 6. Consequently, a free end of a diaphragm type return spring 32 arranged between the hydraulic pump 8 and the clutch 6 is pressed to the clutch 6 side. At this time, the intermediate section of the spring 32 serves as a functioning section for contacting with the clutch and pressing the clutch 6 in engaging direction, and since the other fixed end is fixed in opposite direction from pressing direction, the spring 32 functions as a lever to increase load applied at the free end and applies the load from the functioning section onto the clutch 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a device for transmitting driving force from a predetermined drive shaft to a driven shaft in a four-wheel drive system. The invention relates to a drive coupling device for transmitting power to a rear wheel drive shaft or vice versa from a rear wheel drive shaft to a front wheel drive shaft.

Conventional technology Conventionally, the transformer 77 device that distributes the driving force generated by the engine to all four wheels is a part-time type consisting of a clutch and a chain transmission mechanism, and a full-time type using a differential gear mechanism and a friction clutch. type, and even the so-called real-time type that uses a viscous coupling, are known, but recently, when a difference in rotational speed occurs between the front export force axis and the rear export force axis, A type of device has been proposed in which a hydraulic pump is driven by the relative rotation, and the resulting hydraulic pressure is used to engage a clutch to distribute power to the four wheels (Japanese Patent Application Laid-open No. 102329/1983, 61-10.2330).

However, since the transfer device is installed in addition to the transmission that is already installed, it is preferable to make it as small and light as possible due to space constraints and to reduce the weight of the vehicle. .

From this point of view, the device according to the above proposal has a structure in which a piston is moved by hydraulic pressure generated by a hydraulic pump, and the clutch is pressed and engaged by the piston, so it has a large number of parts and also There was room for further improvement in terms of size and weight reduction, such as the length of the tube.

Therefore, the applicant has proposed a hydraulic pump that is coaxially opposed to a clutch provided between the front export force shaft and the rear export force shaft, and that is driven by the relative rotation of each output shaft, and that moves in the axial direction. A patent application has already been made for a device that can be arranged freely and configured to engage the clutch by moving the hydraulic pump itself to the clutch side using hydraulic pressure generated by relative rotation between the front export force shaft and the rear export force shaft. It was proposed by No. 62-217354.

Problems to be Solved by the Invention However, the device proposed by the present applicant in Japanese Patent Application No. 62-217354 functions as a small piston for a hydraulic pump, so the piston that was conventionally required is omitted, and the number of parts is reduced accordingly. It is possible to reduce the size and weight of the device. However, the above-mentioned device proposed by the present applicant and the above-mentioned Japanese Patent Application Laid-Open Nos. 61-102329 and 61-
In the device described in No. 102330, the hydraulic pump is driven by the relative rotation of the front export force shaft and the rear export force shaft, and the resulting hydraulic pressure is directly applied to the clutch, so the engagement force is increased. In other words, it is necessary to increase the size of the hydraulic pump to increase the generated oil pressure.In other words, the size of the hydraulic pump greatly affects the engagement force of the clutch, so it is not possible to downsize the hydraulic pump. However, there were major constraints in reducing the size and weight of the entire device.

This invention was made against the background of the above-mentioned circumstances, and provides a four-wheel drive drive system that mechanically increases the engagement force of the clutch, thereby reducing the size of the hydraulic pump and, in turn, reducing the size and weight of the entire device. The object is to provide a coupling device.

Means for Solving the Problems In order to achieve the above object, the present invention drives a hydraulic pump by relative rotation between a driving shaft and a driven shaft, and also drives a pressure-responsive member using the hydraulic pressure generated by the hydraulic pump. A four-wheel drive drive coupling device configured to engage a clutch disposed between a drive shaft and a driven shaft by movement of a pressure-responsive member, and return the pressure-responsive member by a return spring. , the clutch and the pressure-responsive member are disposed facing each other on the same axis, the return spring is a diaphragm-type spring, and the diaphragm-type spring is disposed between the clutch and the pressure-responsive member; One end of the inner peripheral end and the outer peripheral end of the spring is a free end that is pressed by the pressure responsive member, and the other end is set at least in the opposite direction to the pressing direction by the pressure responsive member. The diaphragm type spring has a fixed end that is fixed to the diaphragm spring, and an intermediate portion between the inner and outer peripheral ends of the diaphragm type spring is an acting portion that contacts the clutch and presses the clutch in the axial direction. .

Function: In the device of the present invention, when relative rotation occurs between the drive shaft and the driven shaft, for example due to slipping of the front wheel or the rear wheel, the hydraulic pump is driven and hydraulic pressure is generated. The hydraulic pressure causes a pressure-sensitive member, such as a piston or a tenon of the hydraulic pump itself, to be moved. As a result, the free end of the diaphragm spring placed between the pressure-responsive member and the clutch is pressed toward the clutch, and the middle part of the diaphragm spring comes into contact with the clutch and presses the clutch in the engaging direction. Since it is an acting part and the fixed end of the other end is fixed to the free end in the opposite direction to the pressing direction, the diaphragm type spring performs an action similar to a lever and is applied to the free end. Apply the load to the clutch from the action part in increasing steps. Therefore, the hydraulic pump can be downsized in accordance with the effect of increasing the load.

Embodiments Next, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a partial sectional view showing an embodiment of the present invention. In the example shown here, a propulsion shaft for transmitting driving force to wheels is constituted by a driving shaft 1 and a driven shaft 2. axis 1
This is an example in which the shaft is provided between the driven shaft 2 and the driven shaft 2. That is, the connecting portion of these shafts 1 and 2 is covered by a pair of housings 3.4, and the end of the drive shaft 1 is fitted with an O-ring or the like against the inner peripheral surface of the housing 3.4. An inner case 5 that is in sliding contact with each other while maintaining liquid tightness with a sealing material is attached by spline fitting. This inner case 5 also serves as a clutch hub 7 on the outer peripheral side of a friction type clutch 6 and a holder for a hydraulic pump 8, which will be described later. It is rotatably held relative to the housings 3 and 4 by bearings 9 such as bearings and thrust bearings, and three O-rings 10 are attached to the outer periphery of the bearings, so that the inner case 5 and the housing 3.4 are connected to each other. The space between them is closely divided into three parts by an O-ring 10.

On the other hand, a cylindrical member 11 extending toward the drive shaft 1 is attached to the end of the driven shaft 2 by spline fitting. A boss part of this cylindrical member 11 that fits around the outer periphery of the driven shaft 2 serves as a holder for holding a hydraulic pump 8, which will be described later, together with the inner case 5, and a boss part that extends from that part toward the drive shaft 1 side. This portion serves as a clutch hub 12 on the inner peripheral side of a friction type clutch 6, which will be described later.

To explain the friction type clutch 6 here, this clutch 6 is driven by the drive shaft 1! I! A large number of spacer plates 13 are spline-fitted to the inner peripheral surface of the clutch hub 7 on the outer peripheral side, which is a part of the inner case 5, and these spacer plates inner peripheral side clutch hubs 12 that are arranged alternately with respect to the plates 13 and are part of the cylindrical member 11;
It is a wet type multi-disc clutch, which has a friction disk 14 spline-fitted to the outer circumferential surface of the clutch, and further has these spacer plates 13 and friction disks 14 moistened with oil. The structure is such that torque is transmitted by frictional force caused by pressurized contact.

Further, to explain the hydraulic pump 8, the hydraulic pump 8 used here is a vane pump as shown in FIG. It is attached so as to be movable in the axial direction and to rotate integrally with the cylindrical member 11. Further, a cam ring 18 that slides the tip of the vane 17 held by the rotor 15 is movable in the axial direction by a ball spline 19 on the inner periphery of the inner case 5, and rotates integrally with the inner case 5. It is installed like this. Furthermore, a pair of left and right side plates 20.21 are provided between the rotor 15 and the cam ring 18, sandwiching the vane 17 therebetween, and these side plates 20.21 are fixed to the cam ring 18, and It is rotatable relative to the rotor 15. On the side plate 20 on the side of the clutch 6 (on the left side in FIG. 1), suction ports 22 are formed at two locations symmetrical with respect to the center of rotation, and on the other side plate 21, suction ports 22 are formed. On the other hand, three discharge ports 23 are formed at positions 90 degrees out of phase with each other.

To explain the oil passage for circulating oil to the hydraulic pump 8, there is a small hole 24 penetrating from the inner surface to the outer surface in the part of the inner case 5 on the opposite side of the hydraulic pump 8 with the clutch 6 in between. A suction oil passage space 25 is formed between the outer peripheral surface of the inner case 5 and the inner surfaces of the housings 3 and 4, and is partitioned by the O-ring 10 and communicates with the small hole 24. A suction tube 26 is connected to the housing 3 on the left side in FIG. 1 so as to communicate with the suction oil passage space 25. Furthermore, a small hole 27 penetrating from the inner surface to the outer surface is formed in a portion of the inner case 5 that faces the side plate 21 on which the discharge boat 23 is formed. A discharge oil passage space 28 communicating with the small hole 27 and partitioned by the O-ring 10 is formed between the housing 4 and the inner surface of the housing 4, and a discharge oil passage space 29 is connected to the discharge oil passage space 28. is connected to the housing 4. Each tube 26.29 has an opening/closing solenoid valve 30. ffi and an oil reservoir 31. Note that sealing materials such as O-rings are placed at necessary locations to prevent oil leakage and ensure the above-mentioned oil passages.

As is clear from the above description, the clutch 6 and the hydraulic pump 8 are arranged adjacent to each other on the same axis, and there is a diaphragm type return between the clutch 6 and the hydraulic pump 8. A spring 32 is also arranged. As shown in FIG. 3, the shape of the return spring 32 is an annular shape in which the inner circumferential end protrudes in the axial direction relative to the outer circumferential end. The side plate 20 on the left side in FIG. 1 is fixed to the inner peripheral surface of the inner case 5, and the inner peripheral end is a free end and is open to the hydraulic pump 8.
Therefore, the return spring 32 elastically presses the hydraulic pump 8 in the right direction in FIG. The intermediate portion 34 of the return spring 32 is connected to the protrusion 3 on the disk member 35 disposed at the end of the clutch 6.
6 , and its intermediate portion 34 serves as an acting portion that applies a pressing force to the clutch 6 via the protrusion 36 . Note that the outer peripheral end of the return spring 32 is connected to at least the hydraulic pump s.
It is sufficient that it is fixed so as to restrict movement to the side, and there is no need to specifically fix it in the opposite direction. Further, the return spring 32 has an outer peripheral end as a free end, and the hydraulic pump 8
The inner peripheral end is brought into contact with the side plate 20 of the cylindrical member 1.
It may be fixed to 1.

Therefore, in the above configuration, the clutch 6 is pressed through the return spring 32, and the hydraulic pump 8 is movable in the axial direction, and the free end of the return spring 32 is in contact with the hydraulic pump 8. Therefore, the hydraulic pump 8 serves as a means for generating hydraulic pressure and at the same time serves as a pressure-responsive member that moves by hydraulic pressure to press the clutch 6.

Next, the operation of the above device will be explained.

When the propulsion shaft consisting of the drive shaft 1 and the driven shaft 2 is used as the propulsion shaft for the rear wheels of a four-wheel drive vehicle based on FF heavy (front-engine front-wheel drive vehicle), the drive shaft 1 or the transmission or transfer (each not shown) to provide driving force.

When traveling straight on a flat road, the front wheels and the rear wheels rotate at a constant speed, so the drive shaft 1 and the driven shaft 2 rotate at a constant speed and in the same direction, and there is no relative rotation between them. Therefore, since the inner case 5 and the cylindrical member 11 rotate in the same manner, there is no relative rotation between the rotor 15 and the cam ring 18 provided in the hydraulic pump 8, and the hydraulic pump 8 is not driven. In this state, the pump 8 is pushed in a direction away from the clutch 6 by the return spring 32, and as a result, no engagement force is applied to the clutch 6, so it is in a released state.

If there is a difference in the rotation speed between the front and rear wheels when driving steadily on a rough road, there will be a difference between the rotation speed of the drive shaft 1 and the rotation speed of the driven shaft 2, and therefore the inner case A cam ring 18 that rotates integrally with the cylindrical member 5 and a rotor 15 that rotates integrally with the cylindrical member 11 rotate relative to each other. That is, as the rotor 15 rotates with respect to the cam 1 nong 8, oil is sucked into the suction boat 22 through the suction tube 26, the suction oil passage space 25, and the small hole 24, and is pressurized and then released from the discharge boat 23. Sent out. In this case, if the oil passage is closed by the on-off solenoid valve 30, the oil sent out from the discharge boat 23 will be
The flow path from the small hole 27 to the discharge tube 29 via the discharge oil passage space 28 is filled with the fluid. As a result, the pressure on the discharge side of the hydraulic pump 8 increases, and the hydraulic pump 8 is moved toward the suction port 22 side, that is, toward the clutch 6, by the pressure generated by itself.

Accordingly, the inner circumferential end of the diaphragm-type return spring 32 is pushed toward the clutch 6, but the outer circumferential end of the return spring 32 is fixed;
is in contact with the protrusion 36 on the disc member 35, so a pressing force acts on the disc member 35, that is, the clutch 6 via the return spring 32. In that case,
Since the return spring 32 acts as a lever with the inner peripheral end as a force point, the outer peripheral end as a fulcrum, and the intermediate part 34 as a point of action, the positions of these points are determined according to the dimensions shown in FIG. .

11, and the load applied to the inner peripheral end is F, the pressing force Fo on the clutch 6 is Fo=F-1/11 (here, l/11>1>, so in the above configuration, it is not generated by hydraulic pressure. The increased load can be applied to the clutch 6 as a pressing force.

When the pressing force is applied to the disk member 35 as described above, the clutch 6 becomes in a stopped state with a transmission torque capacity corresponding to the pressing force, and the transmission torque from the inner case 5 to the cylindrical member 11, that is, from the drive shaft 1 to the driven Torque is transmitted to the shaft 2. In that case, the transmitted torque varies depending on the pressing force applied to the clutch 6, that is, the pressure generated by the hydraulic pump 8. The pressure generated by the hydraulic pump 8 is applied to the cam ring 18 of the rotor 15, as shown by the solid line in FIG. The higher the relative rotational speed is, the higher the rotational speed becomes. Therefore, when the difference in the rotational speed between the drive shaft 1 and the driven shaft 2 becomes larger, the transmitted torque becomes larger. This is a characteristic similar to that of viscous coupling. Therefore, for example, when the front wheel spins due to a wheel coming off, etc., and the difference in rotational speed between the drive shaft 1 and the driven shaft 2 increases accordingly, a large torque is transmitted to the rear wheel, so that the vehicle can escape from the wheel coming off state. be able to.

In the above-mentioned device, since the return spring 32 acts as a lever, the tendency of the transmitted torque to increase with respect to the relative rotational speed is greater than that in the conventional device (dotted line in FIG. 4). Further, when the return spring 32 is bent in advance and a preload is applied, the characteristic is shown by the chain line in FIG. 4.

By the way, when relative rotation occurs between the drive shaft 1 and the driven shaft 2 and the hydraulic pump 8 generates oil pressure, if the solenoid valve 30 is opened, the pressure on the discharge side of the hydraulic pump 8 will be reduced. Since the height will not rise, the hydraulic pump 8 remains pushed back by the return spring 32.
That is, since the clutch 6 is not pressed, the clutch 6 is maintained in a released state, and as a result, torque is transmitted to the driven shaft 2 side.

The vehicle is in two-wheel drive mode. That is, two-wheel drive and four-wheel drive can be selected by the solenoid valve 30, and part-time four-wheel drive can be achieved.

Incidentally, in the above embodiment, the oil passage on the discharge port side of the hydraulic pump 8 was configured to be closed by the solenoid valve 30, but in the present invention, instead of the solenoid valve 30, a pressure for maintaining the fluid pressure below a certain pressure is used. It is also possible to use a regulating valve or a flow rate regulating valve, in which case the more the flow rate is reduced, the higher the pressure becomes and the more the transmitted torque increases. Furthermore, since the hydraulic pump 8 moves due to the pressure difference between the suction side and the discharge side, in this invention, the oil passage on the suction side of the hydraulic pump 8 is closed or the oil passage area is reduced to lower the pressure on the suction side. , the associated pressure difference,
The hydraulic pump may be moved by

FIG. 5 is a partial sectional view showing another embodiment of the present invention, in which a hydraulic pump 41 is provided concentrically on the inner peripheral side of a clutch 40, and a piston 42 is used as a pressure responsive member. It was there. That is, a front export force shaft 43 as a driving shaft and a rear export force shaft 44 as a driven shaft are arranged on the same axis, and the front export force shaft 43 is mounted on a bearing 47 on a support part 46 provided inside the case 45. It is rotatably supported by and meshes with a drive gear 48 of a transmission (not shown). Further, the rear export force shaft 44 passes through the front export force shaft 43, and its shaft end is fitted into the case 45 in a liquid-tight manner and is rotatably supported. On the other hand, the hydraulic pump 41 has an inner gear 51 and an outer gear 52 housed inside a pair of pump cases 49 and 50 that are joined to face each other in the axial direction.
is located on the outer peripheral side of the rear export force shaft 44 and is arranged in parallel to the front export force shaft 43, and one pump case 49 is fitted to the inner circumference of the front export force shaft 43 via a spline 53. Moreover, the inner gear 51 is spline-fitted to the rear export force shaft 44. Furthermore, each pump case 49, 50 also serves as a clutch hub, and these pump cases 49.5
A large number of friction disks 54 are spline-fitted to the outer circumferential portion of 0. A spacer plate 55 paired with the Mahara disk 54 is spline-fitted to the inner circumferential surface of a clutch drum 56 which is spaced by jΩ so as to cover the outer circumferential side of the hydraulic pump 41 . Clutch drum 56 is spacer plate 5
5 on the inner peripheral surface, a side wall portion substantially perpendicular to the central axis, and a boss portion formed on the inner peripheral edge of the side wall portion. Spline fitted. Further, an annular protrusion 57 of the other pump case 50 of the hydraulic pump 41 extends from the outer circumferential side of the boss portion, and a discharge port 58 and an annular protrusion 57 are opened to the outer circumferential surface of the annular protrusion 57 . An oil passage 59 is formed, and these discharge ports 5
A check pole 61 is provided to switch the oil passage 59 and the oil passage 59 into communication with the oil drain port 60.

A piston 42 is disposed on the outer circumferential side of the annular protrusion 57 so as to move back and forth with respect to the clutch 40, and slides in liquid-tight contact with the outer circumferential surface of the annular protrusion 57 and the inner circumferential surface of the clutch drum 56. . Furthermore, the piston 42 and the clutch 40
A diaphragm-type return spring 62 is disposed between the clutch drum 56 and the clutch drum 56 , and its outer peripheral end is fixed to the inner peripheral surface of the clutch drum 56 by a snap ring 63 to serve as a fixed end, and the inner peripheral end is connected to the piston 42 as a contactor. It is a free end that moves together with the piston 42.

The intermediate portion of the return spring 62 comes into contact with a protrusion 64 of the spacer plate 55 located at the end of the spacer plate 54 on the piston 42 side, and serves as an acting portion that applies a pressing force to the clutch 40.

Note that the oil passage 59 opens into a space on the opposite side of the clutch 40 with the piston 42 in between.

Therefore, in the above device, when there is a difference in the rotational speed between the front export force shaft 43 and the rear export force shaft 44 due to wheel slip etc., the hydraulic pump 41 is driven, and the resulting hydraulic pressure is sent out from the discharge port 58. It will be done. In that case, the check pole 61 is pushed to the right in FIG.
The discharge port 58 and the oil passage 59 are communicated with each other, and hydraulic pressure is supplied to the space on the back side of the piston 42 (the right side in FIG. 5).
The piston 42 moves toward the clutch 40 side. the result,
Although the load is applied to the inner circumferential end of the return spring 62, the outer circumferential end of the return spring 62 is fixed as described above, and the middle part contacts the protrusion 64 of the spacer plate 55 and serves as the acting part. The load from the piston 42 is doubled and acts on the clutch 40.
0 and its pressing force to transmit torque.

That is, torque is transmitted from the front export force shaft 43 to the rear export force shaft 44. Note that the transmitted torque increases depending on the engagement force of the clutch 40, that is, the generated oil pressure.

As a result of the torque being transmitted from the front export force shaft 43 to the rear export force shaft 44 as described above, when the rotation speeds of both become equal, the hydraulic pump 41 is no longer driven and no oil pressure is generated. Since the pole 61 moves to the left in FIG. 5 and the oil passage 59 communicates with the oil drain port 60,
Return spring 62 pushes piston 42 back and clutch 40 is released.

Effects of the Invention As is clear from the above explanation, according to the drive coupling device of the present invention, a load is applied to one end of the diaphragm-type turn spring by the hydraulic pressure generated as a result of relative rotation between the drive shaft and the driven shaft. In this case, the intermediate part between the fixed end and the free end of the return spring is the acting part that applies the pressing force to the clutch, so the return spring The spring acts as a lever, and as a result, it is possible to increase the load applied to the return spring and apply a pressing force to the clutch. Therefore, according to the present invention, since the required hydraulic pressure is low, the hydraulic pump can be made smaller and lighter.As a result, it is possible to obtain a drive coupling device that can be easily mounted on a vehicle, and is also inexpensive. can be taken as a thing. Furthermore, in this invention, since the return spring is a member that directly contacts the clutch and applies a pressing force, by applying a preload to the return spring, the friction disks and spacer plates that make up the clutch are constantly brought into contact with a light load. By doing so, the so-called rift between the two can be resolved.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted sectional view showing an embodiment of the present invention, Fig. 2 is a view taken along the line ■-■ in Fig. 1, Fig. 3 is a schematic sectional view of the return spring, and Fig. The figure is a diagram showing the relationship between different rotational speeds and transmitted torque, and FIG. 5 is a partial sectional view of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Drive shaft, 2... Driven shaft, 6... Friction type clutch, 8... Hydraulic pump, 32... Return spring, 40... Clutch, 41... Hydraulic pump, 42 ...Piston, 43...Front export force shaft, 44...Rear export force shaft, 62...Return spring. Applicant Toyota Motor Corporation

Claims (1)

[Claims] A hydraulic pump is driven by the relative rotation between the drive shaft and the driven shaft, and a pressure-responsive member is moved by the hydraulic pressure generated by the hydraulic pump and is disposed between the drive shaft and the driven shaft. In the four-wheel drive drive coupling device, the clutch is engaged by the movement of the pressure-responsive member, and the pressure-responsive member is moved back by a return spring, wherein the clutch and the pressure-responsive member are arranged on the same axis. The return spring is a diaphragm type spring, and the diaphragm type spring is arranged between the clutch and the pressure responsive member, and either the inner peripheral end or the outer peripheral end of the diaphragm type spring is arranged to face each other on a line. One end is a free end pressed by the pressure responsive member, the other end is a fixed end fixed at least in a direction opposite to the pressing direction by the pressure responsive member, and the diaphragm A drive coupling device for four-wheel drive, characterized in that an intermediate portion between an inner circumferential end and an outer circumferential end of a molded spring serves as an acting portion that contacts the clutch and presses the clutch in the axial direction.