JPH05305831A - Driving force transmission device for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To perform a desired driving force transmission by installing a transfer driving force detecting element, detecting the extent of transfer driving force by a hydraulic pump and an opening control element adjusting the opening of a variable throttle so as to make the actual transfer driving force based on a signal out of this transfer driving force detecting element come nearer to the desired transfer driving force. CONSTITUTION:When such a state that accelerator opening is almost fully opened is detected, whereas a detected speed by a car speed sensor is zero, a desired transfer driving force operational part 11 operates a P characteristic, outputting a signal conformed to this characteristic to an opening control element 10 which drives a driving coil 7, selecting the P characteristic. With this constitution, both front and rear wheels are almost directly connected to each other, whereby separation from a stacked state is made achievable. Since the opening control element 10 feedbacks the actual transfer driving force given out of a transfer driving froce detecting element 9, yet more accurate driving transmission is achievable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel drive vehicle in which a hydraulic pump interposed between front and rear wheels realizes a four-wheel drive state through hydraulic pressure generated according to a rotational speed difference between the two wheels. Driving force transmission device.

[0002]

2. Description of the Related Art A four-wheel drive vehicle that travels by transmitting the driving force of an engine to both the front and rear wheels is not only excellent in running on bad roads, but also in terms of acceleration and running stability on ordinary roads. Because it is excellent, it is rapidly becoming popular. In recent years, when a difference in rotational speed occurs between the front and rear wheels, a drive force transmission device that changes the distribution of the drive force to both wheels according to the difference in rotational speed is provided, and the four-wheel drive state is practically always maintained. The so-called full-time four-wheel drive vehicles that have been made available are the mainstream. As one of such driving force transmission devices,
It is known to utilize the hydraulic pressure generated by a hydraulic pump interposed between the rear wheels. This is because a hydraulic pump (generally a vane pump) is configured by housing a rotor that is rotated in conjunction with a transmission shaft for one of the front and rear wheels in a casing that is rotated in conjunction with the transmission shaft for the other, and In the pump chamber formed between the rotor and the rotor, hydraulic pressure is generated according to the rotational speed difference between both transmission shafts, and the driving force is transmitted between the front and rear wheels via this hydraulic pressure. It is a thing.

At this time, the hydraulic pressure generated corresponding to the magnitude of the relative rotation, that is, the magnitude of the rotational speed difference between the front and rear wheels, inhibits the relative rotation between the rotor and the casing. Since the hydraulic pressure acts, the driving force corresponding to the rotational speed difference between the front and rear wheels is transmitted from one side to the other side between the front and rear wheels, so that a so-called four-wheel drive state is realized.

[0004]

By the way, for the purpose of obtaining an appropriate driving force transmission characteristic according to the running state, a variable throttle is provided in the middle of the oil passage on the discharge side of the hydraulic pump, and a plurality of states related to the running state are provided. There is provided a driving force transmission device provided with an opening control unit that adjusts the opening of the variable throttle based on a combination of amounts (for example, vehicle speed, steering angle, presence / absence of brake operation, accelerator opening, etc.). .. In this driving force transmission device, for example, it is possible to reduce the transmission driving force in order to prevent the occurrence of a tight corner braking phenomenon at the time of low speed turning, while obtaining a high transmission driving force when required. That is, there is an advantage that the driving force transmission characteristic can be changed according to the traveling state.

However, in the conventional driving force transmission device, since the so-called feedforward control is performed in which the actual transmission driving force is not sensed, there is hysteresis in the characteristics of the electric / hydraulic circuit system. When the rising characteristics of the control transmission drive force and the drive force response change due to the influence of the change in oil viscosity due to the change in oil temperature, the desired drive force cannot be transmitted. However, there is a problem that the desired driving force distribution cannot be obtained.

The present invention has been made in view of the above problems, and a drive for a four-wheel drive vehicle capable of controlling a transmission drive force with high precision and responsiveness and transmitting a desired drive force. An object is to provide a force transmission device.

[0007]

A driving force transmission device for a four-wheel drive vehicle according to the present invention for solving the above problems is interposed between front and rear wheels and is generated according to a difference in rotational speed between the two wheels. The hydraulic pump that transmits the driving force between the two wheels via the hydraulic pressure, and the driving force transmission characteristic to the front and rear wheels, which is arranged on the discharge side of the hydraulic pump and changes the throttle opening, uses the hydraulic pressure as a medium. In a four-wheel drive vehicle driving force transmission device having a variable aperture for changing the, based on a combination of a plurality of state quantities related to the running state, a target transmission driving force calculation unit for calculating the target transmission driving force, A transmission drive force detection unit that detects the transmission drive force by the hydraulic pump, and an opening that adjusts the opening of the variable throttle so that the actual transmission drive force based on the signal from the transmission drive force detection unit approaches the target transmission drive force. Characterized by having a degree control unit A.

[0008]

According to the four-wheel drive vehicle driving force transmitting device having the above-described structure, the opening control portion performs feedback control so that the actual transmitting driving force approaches the target transmitting driving force.
It is possible to eliminate the influence of the hysteresis characteristic of the electric / hydraulic circuit system, the change in oil temperature, and the like, and it is possible to control the transmission driving force with high accuracy and to improve the responsiveness to the change in the command transmission driving force.

[0009]

Embodiments will be described below with reference to the accompanying drawings showing embodiments. FIG. 1 is a drive force transmission device for a four-wheel drive vehicle (hereinafter, simply referred to as a drive force transmission device) as an embodiment of the present invention.
Is shown. This driving force transmission device is interposed between an input shaft 1 connected to a front wheel F and an output shaft 2 connected to a rear wheel R, and responds to a difference in rotational speed between the input and output shafts 1 and 2. Vane pump 3 as a hydraulic pump for transmitting the driving force between the two wheels F and R, a variable throttle mechanism 6 for varying the discharge pressure of the vane pump 3, and an opening degree control for controlling the throttle opening degree of the variable throttle mechanism 6. The unit 10, the transmission driving force detection unit 9 that detects the actual transmission driving force by the vane pump 3, and the target transmission driving force calculation unit 11 that calculates the target transmission driving force based on the signal from the predetermined input sensor 12. I have it. The input sensor 12 includes a vehicle speed sensor, a steering angle sensor, a brake sensor, an accelerator opening sensor, and various other running state detection sensors.

Cylindrical rotor 30 of vane pump 3
Is formed with a plurality of storage grooves having a predetermined depth in the radial direction from the outer peripheral surface in the circumferential direction, and the rectangular flat vane 30a is stored in each of the storage grooves so as to be movable in the radial direction. It has a known configuration. A compression coil spring 30b is interposed between each vane 30a and the bottom of the storage groove thereof to bias the vane 30a outward in the radial direction.
The casing of the vane pump 3 encloses the rotor 30 and is sandwiched by a pair of annular side plates 32 and 33, and a cam ring 31 that forms a plurality of pump chambers with the rotor 30, and the side plates 32 and 3 described above.
3 and a pressing plate 34, and a plurality of fixing bolts 3 that penetrate through these in the thickness direction and are screwed into the side plate 32.
5, they are integrally rotatably connected.

As a result, inside the cam ring 31,
The side plate 32 and the side plate 33 form a cavity surrounded by both sides, and the rotor 30 is housed in the cavity. The rotor shaft 4, which is the rotating shaft of the rotor 30, is inserted from the side plate 33 side into the hollow portions of the side plates 32, 33, and is supported by ball bearings on both sides of the cam ring 31, as shown in the figure.

The rotor 30 is splined to the rotor shaft 4 between these bearing positions, and rotates while pressing the tip of the vane 30a against the inner circumference of the cam ring 31 as the rotor shaft 4 rotates. The inner circumference of the cam ring 31 has a cross-sectional shape formed by forming a plurality of recesses around a circle, and a plurality of outer circumferences of the rotor 30 are surrounded by the positions where these recesses are formed. A pump chamber is formed.

The input shaft 1 is connected to the end of the rotor shaft 4 which projects toward the side plate 33, and the output shaft 2 is connected to the side plate 32 via a connecting member 5 which will be described later. It is connected to the outer surface. This allows
The rotor 30 is interlocked with the rotation of the input shaft 1 connected to the front wheel F, and the casing including the cam ring 31 as a part thereof is
Since it is interlocked with the rotation of the output shaft 2 connected to the rear wheel R, a front wheel F and a rear wheel R are provided between the rotor 30 and the cam ring 31.
Relative rotation will occur depending on the difference in rotational speed between and.

A thin cylinder 36 is fitted on the outside of the casing, and an annular oil tank T is formed between the cylinder 36 and the outer circumference of the casing. The oil of the vane pump 3 is filled in the oil tank T.
Each pump chamber of the vane pump 3 is formed by penetrating the disc portions of the pressing plate 34 and the side plate 33 in the thickness direction, and mounting a check valve in the middle thereof that allows only the inflow into the pump chamber. The oil tank T is communicated with another suction oil passage 40.

The side plate 32 is provided with a check valve having one end opened in each pump chamber, folded back inward in the radial direction and connected to the bottom of the storage groove of the vane 30a, and allowing only the outflow from each pump chamber. Separate discharge oil passages 41 are formed by being fitted in. Further, the side plate 32 has an oil guide hole 4 penetrating therethrough in the thickness direction.
2 and a return hole 43 that also penetrates in the radial direction. One end of the oil guide hole 42 is opened to the inner side surface of the side plate 32 so as to communicate with the bottom of the storage groove, and the other end thereof is an annular groove 37 formed in a connecting flange 51 described later.
The side surface of the side plate 32 is open to communicate with the. As a result, the oil guide hole 42 communicates the bottom of the storage groove with the annular groove 37. Further, the return hole 43 communicates the hollow portion of the side plate 32 with the oil tank T.

FIG. 2 is an enlarged sectional view of a variable diaphragm mechanism 6 which constitutes a variable diaphragm for changing the driving force transmission characteristics to the front and rear wheels as described later. The connecting member 5 includes a non-magnetic holding cylinder 50 between the pair of connecting flanges 51 and 52.
It is clamped and fixed by a plurality of fixing bolts 53. The one connecting flange 51 is coaxially fixed to the outer surface of the side plate 32, and the other connecting flange 52.
Are coaxially fixed to the end portion of the output shaft 2, whereby the connecting member 5 connects the casing of the vane pump 3 and the output shaft 2. The connecting flange 51 is provided with a through hole 51 a, which is aligned with the inner circumference of the holding cylinder 50, in its axial center portion. A first diaphragm member 61 having a cylindrical shape is slidably fitted in the inside of the holding cylinder 50 and the through hole 51a of the connecting flange 51, and is slidably fitted in the holding flange 50. A second diaphragm member 62 adjacent to the first diaphragm member 61 is slidably fitted in the through hole 51a. The first throttle member 61 is moved in the left direction of the drawing, that is, the second throttle member, by the biasing spring 60 interposed between the inner peripheral step of the first throttle member 61 and the concave hole of the coupling flange 52. It is biased toward the member 62 side (side plate 32 side). The second throttle member 62 is connected to the flange portion of the second throttle member 62 and the connecting flange 51.
Is urged toward the side plate 32 by an urging spring 63 interposed between the end plate and the end face.

A stop ring 64 is engaged with the inner periphery of the connecting flange 51 near the opening end, and the second throttle member 62 urged by the urging spring 63 slides against the stop ring 64.
Regulated by abutting against. The sliding of the first throttle member 61 urged by the urging spring 60 is restricted by coming into contact with the second throttle member 62 locked by the stop ring 64. On the other hand, the distance between the retaining ring 64 and the connecting flange 52 is set to be longer than the total length of the throttle members 61 and 62 by a predetermined distance.
The sliding range of both diaphragm members 61, 62 is limited to the above predetermined distance.

An annular throttle groove 65 is formed on the outer periphery of the second throttle member 62, and the throttle groove 65 is formed by a communication hole 66 penetrating the peripheral wall of the second throttle member 62 to form a central hole 62a. Is in communication with. A throttling groove 54 is formed in the inner peripheral portion of the through hole 51 a of the connecting flange 51, and the throttling groove 54 is connected to the annular groove 3 via the communication hole 55.
It is connected to 7. The aperture area of the aperture groove 54 between the end faces of the first aperture member 61 and the second aperture member 62 is changed depending on how the outer periphery of the first aperture member 61 is closed. The opening area is changed according to the sliding movement of the first diaphragm member 61.

On the side plate 32 side of the through hole 51a of the connecting flange 51 with respect to the throttle groove 54, the throttle groove 5 is formed.
6 is formed, and the throttle groove 56 communicates with the annular groove 37 via the communication hole 57. Connection flange 51
The area of communication between the diaphragm groove 56 and the diaphragm groove 65 of the second diaphragm member 62 changes according to the sliding movement of the second diaphragm member 62.

The annular groove 37 is provided with oil guide holes 42 and vanes 3.
Each of the pump chambers of the vane pump 3 communicates with each other through the storage groove 0a and the discharge oil passage 41. Further, the through hole 61 a of the first throttle member 61 corresponds to the through hole 51 of the connecting flange 51.
a, the central hole 62a of the second throttle member 62, the hollow portion of the side plate 32, and the return hole 43, which communicate with the oil tank T. Therefore, both diaphragm members 61, 62
Means that the discharge side of each pump chamber is arranged in the middle of the discharge-side oil passage that communicates with the oil tank T, and the change of the opening area of the throttle groove 54 and the throttle groove 56 in accordance with the above-mentioned sliding. By changing the area of communication with the aperture groove 65, the aperture functions as a variable aperture that acts as an aperture.

The driving of the diaphragm members 61, 62 is carried out by the holding cylinder 5.
It is performed by a solenoid having its own iron core by a magnetic field formed by a drive coil 7 that is provided so as to surround the outside of 0. The function as the iron core is realized by making all or part of the diaphragm members 61 and 62 made of a magnetic material. The drive coil 7 is fitted in the center of the inside of a support cylinder 8 which supports the holding cylinder 50 inside thereof in a coaxially rotatable manner.
Together with this support cylinder 8, it is non-rotatably restrained to a part of the vehicle body through a connecting member 80 made of a material having a high elasticity such as hard rubber.

With this configuration, the drive coil 7 is provided in the vicinity of the outer peripheral surface of the holding cylinder 50 without changing the relative position in the radial direction with respect to the diaphragm members 61 and 62, while the holding cylinder 50 is not mounted as described above. Since it is made of a magnetic material, the magnetic field generated by energizing the drive coil 7 is stably concentrated at the positions where the diaphragm members 61 and 62 are provided without leaking to the holding cylinder 50. Due to the action of this magnetic field, the diaphragm members 61, 62
Is applied with a force in a direction against the urging force of the urging springs 60 and 63, and the diaphragm members 61 and 62 slide to the right in the figure in response to the energization of the drive coil 7. However, the aperture area and the like are enlarged. The drive coil 7 is
Depending on the magnitude of the applied voltage, it is selectively driven into a full load state, a half load state and a no load state.

In the unloaded state, each throttle member 6
1, 62 are located at the leftmost position in the figure, and the throttle groove 54 and the throttle groove 56 are closed. In this state, the communication between the pump chamber and the oil tank T is cut off,
The P characteristic shown in FIG. 3, which is the highest transfer characteristic, is obtained. Further, in the half-load state, the pump chamber and the oil tank T are communicated with each other with only the throttle groove 54 being opened, and an intermediate transfer characteristic, the N characteristic shown in FIG. 3, is obtained. Further, in the full load state, the pump chamber and the oil tank T are communicated with each other with both throttle grooves 54 and 56 opened, which is the lowest transmission characteristic, that is, S shown in FIG.
The characteristics are obtained.

The transmission driving force detecting section 9 measures the hydraulic pressure introduced from the oil guiding hole 42, which serves as a hydraulic path on the high pressure side of the vane pump 3, to the measuring oil chamber 44 through the communicating hole, and the high pressure side pressure sensor P1. Based on the detection signal from the low pressure side pressure sensor P2 which measures the hydraulic pressure introduced from the oil tank T as the low pressure side hydraulic path of the vane pump 3 to the measurement oil chamber 45 through the communication hole, the actual value obtained by the following formula A signal corresponding to the transmission driving force A of is output to the opening degree control unit 10.

A = (p1−p2) · Q / 2π where p1 is the high pressure side pressure detected by the high pressure side pressure sensor P1, p2 is the low pressure side pressure detected by the low pressure side pressure sensor P2, and Q is the vane pump. 3 is the discharge amount of oil per one rotation. In addition, each pressure sensor P1, P
2 is attached to the connecting flange 51 so as to face the measurement oil chambers 44 and 45 while maintaining the liquid-tight state of the measurement oil chambers 44 and 45. Signals from the pressure sensors P1 and P2 are transmitted through separate slip rings 58 that rotate integrally with the outer periphery of the coupling flange 51, and fixed terminals 59 that contact the slip rings 58 while allowing the rotation of the slip ring 58. Is transmitted to the transmission driving force detection unit 9.

The target transmission driving force calculation unit 11 calculates one of the above P, N, and S characteristics as the target transmission driving force according to a predetermined control map. For example, when the vehicle speed detected by the vehicle speed sensor is equal to or less than a predetermined value (for example, 10 km / h) and the steering angle detected by the steering angle sensor is large, the S characteristic is calculated and a signal corresponding to the S characteristic is calculated. Output to. Upon receiving this, the opening degree control unit 10 drives the drive coil 7 to select the S characteristic. As a result, the front and rear wheels F, R are loosely connected, and the front,
This is because it is possible to reasonably absorb the difference in rotational speed between the two wheels F and R due to the difference in the turning loci of the rear wheels, and it is possible to reliably prevent the occurrence of the tight corner braking phenomenon. On the other hand, if the accelerator opening sensor detects that the accelerator opening is almost fully open even though the speed detected by the vehicle speed sensor is zero (this is the so-called stuck state), the target transmission is performed. The driving force calculation unit 11 calculates the P characteristic and outputs a signal corresponding to the P characteristic to the opening degree control unit 10. Upon receiving this, the opening degree control unit 10 drives the drive coil 7 to select the P characteristic. This is because the front and rear wheels F and R are substantially directly connected to each other, and it is possible to escape from the stack state.

In the above control, the opening control section 10 feeds back the actual transmission driving force given from the transmission driving force detecting section 9, so that the driving force can be transmitted more accurately. For example, in a case where the actual characteristics P, N, S are significantly decreased due to the increase in the oil temperature, even if the one calculated by the target transmission driving force calculation unit 11 is the N characteristic, A desired driving force is transmitted by the opening degree control unit 10 selecting a P characteristic higher than this.

Further, the opening control section 10 is adapted to appropriately select the P characteristic, the N characteristic and the S characteristic so as not to adversely affect the ABS operation. According to this embodiment, feedback control is performed by the opening degree control unit 10 so that the actual transmission driving force approaches the target transmission driving force, so that the influence of the hysteresis characteristic of the electric / hydraulic circuit system, the change in the oil temperature, and the like. Can be eliminated, the transmission driving force can be controlled with high accuracy, and the responsiveness to changes in the command transmission driving force can be improved. Therefore, it is possible to transmit a desired driving force suitable for the traveling state.

Further, the opening control section 10 can appropriately adjust the transmission torque characteristic at a level at which the adverse effect on the ABS operation during braking can be avoided. Similarly, it is also suitable for application to a traction control system. The present invention is not limited to the above-mentioned embodiment, and the two shafts separated by a predetermined distance in the axial direction of the output shaft 2 can be used.
Rotation speed (peripheral speed) of output shaft 2 at each position
Torque can be detected based on the rotational phase difference between the above two positions due to the twist of the output shaft 2, etc.
Various design changes can be made without changing the gist of the present invention.

[0030]

According to the present invention, the opening control section performs feedback control so that the actual transmission driving force approaches the target transmission driving force. Therefore, the hysteresis characteristic of the electric / hydraulic circuit system and the oil temperature change are controlled. It is possible to eliminate the influence of, etc., and control the transmission drive force with high accuracy,
Responsiveness to changes in the command transmission driving force can also be improved, and thus desired driving force transmission can be performed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a drive force transmission device for a four-wheel drive vehicle as an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a main part of a drive force transmission device for a four-wheel drive vehicle.

FIG. 3 is a graph showing driving force transmission characteristics.

[Explanation of symbols]

 3 vane pump (hydraulic pump) 6 variable throttle mechanism 9 transmission drive force detection unit 10 opening control unit 11 target transmission drive force calculation unit F front wheel R rear wheel

Claims (1)

[Claims] 1. A hydraulic pump interposed between front and rear wheels for transmitting driving force between the two wheels via hydraulic pressure generated according to a rotational speed difference between the two wheels, and a hydraulic pump disposed on a discharge side of the hydraulic pump. In the driving force transmission device for a four-wheel drive vehicle, which is provided with a variable throttle that changes the driving force transmission characteristics to the front and rear wheels via the hydraulic pressure by changing the throttle opening, Based on the combination of multiple state quantities,
The target transmission driving force calculation unit that calculates the target transmission driving force, the transmission driving force detection unit that detects the transmission driving force by the hydraulic pump, and the actual transmission driving force based on the signal from the transmission driving force detection unit is the target transmission driving force. A drive force transmission device for a four-wheel drive vehicle, comprising: an opening control unit that adjusts the opening of the variable throttle so as to approach the force.