JP2949299B2 - Drive coupling device for four-wheel drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a four-wheel drive state in which a hydraulic pump interposed between a front wheel and a rear wheel is used as a medium for a hydraulic pressure generated in accordance with a rotational speed difference between the two wheels. The present invention relates to a four-wheel drive drive coupling device that realizes the above.

[Conventional technology]

A four-wheel drive vehicle that travels by transmitting the driving force of the engine to both the front and rear wheels has been spotlighted as being capable of achieving stable traveling regardless of natural conditions such as road surface conditions, weather, and traveling conditions. ing. In recent years, when a rotational speed difference occurs between the front and rear wheels, a drive coupling device that performs an operation of changing the distribution of the driving force to both wheels in accordance with the rotational speed difference is provided, and substantially four-wheel drive is provided. A so-called full-time four-wheel drive vehicle, which is capable of obtaining a state, is the mainstream. As one of such four-wheel drive drive coupling devices, a hydraulic pump interposed between front and rear wheels There is known a device that utilizes generated hydraulic pressure. The hydraulic pump (generally, a vane pump) is constructed by housing a rotor interlocked to a transmission shaft to one of the front and rear wheels in a casing interlocked to transmission oil to the other wheel. A relative rotation corresponding to the rotational speed difference between the transmission shafts, that is, the rotational speed difference between the front and rear wheels, is generated between the rotor and the casing, and at this time, the hydraulic pressure generated in the pump chamber formed between the two is transmitted. The driving force is transmitted between the two transmission shafts. At this time, the hydraulic pressure generated corresponding to the magnitude of the relative rotation, that is, the magnitude of the rotational speed difference generated between the front and rear wheels, is:
Since the relative rotation between the rotor and the casing acts to suppress the relative rotation, a driving force corresponding to the rotational speed difference between the two wheels is transmitted from one of the front and rear wheels to the other through the hydraulic pressure. Thus, a desired four-wheel drive state is realized.

In a four-wheel drive vehicle, when importance is placed on preventing the occurrence of tight corner braking caused by turning, it is desirable that a loose connection between the front and rear wheels be obtained. Contrary to this, when it is important to improve the stability of the vehicle, it is desirable to obtain a rigid connection state, and it is required to change the transmission characteristics according to the traveling state such as the presence or absence of steering, the level of the vehicle speed, and the like. In the above-described drive coupling device in which the pressure generated by the hydraulic pump is transmitted as a driving force transmission medium, the transmission characteristics can be changed by changing the pressure characteristics of the hydraulic pump. Depends on oil resistance. Therefore, a variable throttle having a throttle member driven by a solenoid is arranged in the middle of the discharge-side oil passage, and energization control to the solenoid is performed based on a detection result of a traveling state, and the throttle opening of the variable throttle is controlled. There has been proposed a drive coupling device configured to respond to a request for changing the transmission characteristics by continuously changing the transmission characteristics.

[Problems to be solved by the invention]

However, in this drive coupling device, in order to continuously change the opening degree of the throttle, a solenoid for driving the throttle member has a complicated structure, and in order to continuously control the energization to the solenoid. A control unit having a complicated configuration is required, which not only increases the cost but also causes a high probability of occurrence of malfunctions of the solenoid and the control unit, and has low reliability.

The present invention has been made in view of such circumstances, and realizes a plurality of different transmission characteristics by a simple configuration of a solenoid for driving a diaphragm member and a control unit for energizing the solenoid to improve reliability. It is another object of the present invention to provide a four-wheel drive drive coupling device that can contribute to cost reduction.

[Means for solving the problem]

The drive coupling device for four-wheel drive according to the present invention rotates on one of the front and rear wheels on the discharge side of a hydraulic pump that is interposed between the front and rear wheels and generates hydraulic pressure according to the rotational speed difference between the two wheels. A throttle member is provided at the axis of the holding member to be driven, and is driven by a solenoid. By the action of a magnetic field formed by energizing a drive coil of the solenoid, the urging spring is pressed against the biasing spring. In the four-wheel drive drive connection device for moving the throttle member to adjust the oil flow resistance on the discharge side to change the transmission characteristics to the front and rear wheels via the hydraulic pressure, the urging spring may be A plurality of springs interposed between the throttle member and the holding member and arranged in parallel or in series, and the drive coil can be separately energized, and the throttle member A plurality of juxtaposed to form a magnetic field Characterized in that it comprises a yl.

[Action]

In the present invention, the throttle member urged by the plurality of springs arranged in parallel or in series is changed in a plurality of stages against the urging force of each spring by stepwise changing the energizing current to the drive coil. The diaphragm member is moved, and a predetermined current is supplied to the plurality of coils of the drive coil, and the magnetic field of different strength formed at the position where the diaphragm member is disposed at the time of each energization is used. Is moved in a plurality of stages to eliminate the need for complicated energization control of the solenoid for driving the aperture member.
Different transmission characteristics are realized by a compact configuration.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is a longitudinal sectional view of a drive connection device for four-wheel drive (hereinafter referred to as the device of the present invention) according to the present invention.

The device of the present invention provides a rotational speed difference between both shafts 1 and 2 between an input shaft 1 that rotates in conjunction with one of the front and rear wheels and an output shaft 2 that rotates in conjunction with the other, that is, a difference between the front and rear wheels. A hydraulic pump (vane pump 3) that generates a hydraulic pressure according to the rotational speed difference is configured to transmit driving force from the input shaft 1 to the output shaft 2 using the hydraulic pressure generated by the vane pump 3 as a medium.

The rotor 30 having a short cylindrical shape of the vane pump 3 has a plurality of grooves having a predetermined depth in a radial direction from an outer peripheral surface and formed in the circumferential direction at equal intervals, and each of these grooves has a rectangular flat plate-shaped vane.
Has a well-known configuration in which the vanes 30a, 30a ... are housed so as to be able to advance and retreat in the radial direction. The biasing coil springs 30b are interposed. Vane pump 3
The casing has a cam ring 31 having an unbalanced cylindrical shape having substantially the same length as the rotor 30, and a pressure plate 32 which is a thick hollow disk, and both are coaxially connected to the inner peripheral side of the hollow disk. A side plate 33 having a cylindrical portion and a holding plate 34 are provided.The cylindrical portion of the holding plate 34 is externally fitted to the cylindrical portion of the side plate 33 so that the two are coaxially integrated with each other. Are coaxially positioned on both sides of the cam ring 31, a plurality of fixing bolts 35, which penetrate the disc portion of the holding plate 34 and the side plate 33 and the cam ring 31 in the thickness direction and are screwed to the pressure plate 32. With 35 ..., all of them are integrally connected. With this configuration, a cavity is formed inside the cam ring 31 on both sides surrounded by the pressure plate 32 and the side plate 33, and the rotor 30 is housed in the cavity. The rotor shaft 4 that is the rotation shaft of the rotor 30 is
Is inserted from the side plate 33 side into the hollow portion of the pressure plate 32 and a hollow portion of the pressure plate 32, and a ball bearing on the pressure plate 32 side and a needle roller bearing on the side plate 33 side are provided on both sides of the cam ring 31 as shown in the figure. It is supported. The rotor 30 is spline-coupled to the rotor shaft 4 between these bearing positions, and is located coaxially with the inside of the cam ring 31. As the rotor shaft 4 rotates, the rotors 30 are connected to the vanes 30a, 30a,. It rotates while pressing the tip against the inner periphery of the cam ring 31. The inner periphery of the cam ring 31 has an axial cross-sectional shape in which a plurality of recesses are formed around the circumference of the circle, and a plurality of recesses surrounded by the outer periphery of the rotor 30 at positions where these recesses are formed. A pump chamber is formed.

The input shaft 1 is connected to an end of a rotor shaft 4 protruding toward the side plate 33, and the output shaft 2 is connected to an outer surface of a pressure plate 32 via a connecting member 5 configured as described later. Connected to. As a result, the rotor 30
Rotates in conjunction with the rotation of the input shaft 1, and the casing having the pressure plate 33 as a part thereof rotates in conjunction with the rotation of the output shaft 2, so that the input shaft is provided between the rotor 30 and the cam ring 31. 1 and the output shaft 2, that is, relative rotation corresponding to the difference in rotation speed between the front and rear wheels occurs.

A thin cylinder 36 is fitted on the outside of the casing,
The hydraulic oil of the vane pump 3 is sealed in an oil tank T formed in an annular shape between the cylinder 36 and the outer periphery of the casing. Each of the pump chambers of the vane pump 3 penetrates through the disc portions of the holding plate 34 and the side plate 33 in the thickness direction, and each of the pump chambers is fitted with a check valve that allows only the flow into the pump chamber. (Only one is shown) communicates with the oil tank T. In the pressure plate 32, one end is opened in each pump chamber, and the vane 30a,
Each of the discharge oil passages 41, 41 ... (only one is shown) formed by fitting a check valve which is connected to the bottom of the storage groove of 30a ... and allows only outflow from each pump chamber in the middle thereof. It is. The pressure plate 32 has an oil guide hole 42 penetrating it in the thickness direction and a return hole similarly penetrating the radial direction.
43 is formed. The oil guide hole 42 is in the pressure plate 32
One end is opened at a radial position corresponding to the bottom of the storage groove on the inner surface, and the other end is opened in an annular groove 37 provided on the inner periphery of the outer surface of the pressure plate 32, thereby forming the storage groove. The bottom communicates with the annular groove 37, and the return hole 43 communicates the hollow portion of the pressure plate 32 with the oil tank T.

2 and 3 are enlarged cross-sectional views of a characteristic portion of the device of the present invention. The connecting member 5 includes a pressure plate 32
And is interposed between the output shaft 2 to connect the two,
It holds the throttle member 6 for adjusting the oil flow resistance of the discharge-side oil passage of the vane pump 3 by its movement, and is provided between the connection flanges 51 and 52 for connection with the pressure plate 32 and the output shaft 2. A holding tube 50 made of a non-magnetic material is coaxially held and fixed. This clamping is performed by penetrating the connecting flange 52 in the thickness direction, further penetrating the peripheral wall of the holding cylinder 50 in the longitudinal direction, and fixing a plurality of fixing bolts 53, 5 screwed to the connecting flange 51.
It is done by tightening 3. The connection flange 51 on the pressure plate 32 side is a hollow disc-shaped member having a circular hole 51a aligned with the inside of the holding cylinder 50 at its axial center position. It is fitted in the holding cylinder 50 through the hole 51a so as to be slidable on the axis. The aperture member 6 is moved toward the left in the drawing, that is, toward the pressure plate 32 by an urging spring 60 interposed between the aperture member 6 and an end of the other side connection flange 52 that protrudes into the holding cylinder 50 by a predetermined length. Has been energized. Retaining ring 6 on the inner circumference near the open end of circular hole 51a
1 is engaged, and the sliding range of the throttle member 6 is limited between the retaining ring 61 and the end of the connecting flange 52.

On the outer peripheral surface of the aperture member 6, an aperture groove 63 is formed in an annular shape, and the aperture groove 63 is formed with a communication hole 64 penetrating the peripheral wall.
Through the aperture member 6. A throttle groove 54 is formed in an inner periphery of the circular hole 51a of the connection flange 51 so as to form an annular shape.
Is fixed so as to communicate with the annular groove 37 formed on the outer surface of the pressure plate 32 through the communication hole 55. The throttle groove 54 and the throttle groove 63 correspond to the throttle member 6.
Are always in communication as long as they move within the above-described sliding range, while the annular groove 37 is formed via the oil guide hole 42, the storage groove for the vanes 30a, 30a, and the discharge oil passages 41, 41,. Vane pump 3
The inside of the throttle member 6 has a hollow portion of the pressure plate 32 and the return hole 43.
Through the oil tank T. As a result, the throttle member 6 is disposed in the middle of the discharge-side oil passage that connects the discharge side of each of the pump chambers to the oil tank T.
A throttle action is performed by a change in a communication area generated between the throttle member 63 and the throttle groove 63 in accordance with sliding of the throttle member 6. When the throttle member 6 is pressed against the retaining ring 61 by the spring force of the urging spring 60, the throttle area becomes maximum as shown in FIG.
As the throttle member 6 slides against the spring force of the urging spring 60, it decreases as shown in FIG.

The drive of the aperture member 6 is performed by a solenoid having an iron core itself by the action of a magnetic field formed by a drive coil 7 provided around the outside of the holding cylinder 50 in order to enable this drive. The whole or a part of the aperture member 6 is made of a magnetic material. The drive coil 7 has the holding cylinder
50 is fitted to the center of the inside of a bearing tube 8 that supports the same coaxially rotatable, and together with the bearing tube 8, is connected to a part of the vehicle body via a connecting member 9 made of an elastic material such as hard rubber. Being restrained in a non-rotating state. With this configuration, the drive coil 7
Is provided around the outer peripheral surface of the holding cylinder 50 without changing the relative position with respect to the aperture member 6, while the holding cylinder 50 holding the aperture member 6 is made of a non-magnetic material. The magnetic field generated by energization of the diaphragm 7 is stably concentrated at the position where the diaphragm member 6 is disposed without leaking to the holding cylinder 50, and the diaphragm member 6 has a force against the urging force of the urging spring 60. Is added, whereby the diaphragm area is reduced in accordance with the sliding of the diaphragm member 6 which occurs to the right in the drawing. The drive coil 7 is energized in accordance with an energization command issued from an energization control unit 10 (see FIG. 1) based on a detection result of a running state such as presence or absence of steering, vehicle speed and the like.

As shown in FIGS. 2 and 3, the biasing spring 60 includes two coil springs 60a and 60b having different diameters arranged in parallel on the same axis. The pressing of the aperture member 6 against the retaining ring 61 is performed by the urging of a large-diameter coil spring 60a as shown in FIG.
The leading end of b has a predetermined distance S
Separated. Therefore, the sliding of the aperture member 6 can be performed against the small urging force of the coil spring 60a alone before the sliding distance reaches the predetermined distance S, whereas the sliding distance is equal to the predetermined distance S. To reach the coil spring 60 as shown in FIG.
After contacting the tip of b, both coil springs 60
a, requires the action of force against the large biasing force of 60b. This means that the position where the sliding of the distance of S has occurred,
That is, it is shown that the positioning of the aperture member 6 to the sliding position shown in FIG. 3 is easy, and the sliding position shown in FIG. 3 is easily realized by roughly adjusting the current supplied to the drive coil 7. it can. That is, in the device of the present invention, the driving coil 7
By roughly adjusting the energizing current to the two stages, the sliding position shown in FIG. 3 and the sliding position where the contact with the connecting flange 52 occurs can be realized. In addition to the sliding positions shown in FIGS. 2 and 3, three different sliding positions, in other words, three different throttle openings, can be realized reliably and easily. The spring constants of the coil springs 60a and 60b may be set appropriately.However, the spring constant of the coil spring 60a is set sufficiently smaller than that of the other coil spring 60b, and the urging force of only the former and the urging force of both are set. By increasing the difference, the allowable range of the current flowing through the drive coil 7 necessary for maintaining the middle throttle opening degree shown in FIG. 3 can be set wider.

In the device of the present invention configured as described above, when a rotation speed difference occurs between the input shaft 1 and the output shaft 2, the relative rotation at a speed corresponding to the rotation speed difference is performed by the vane pump 3.
Between the rotor 30 and the cam ring 31, and the hydraulic oil in the oil tank T is introduced into each pump chamber via the suction oil passage 40 which is opened on the upstream side in the relative rotation direction, and is adjacent to each other. The pump is sealed between the vanes 30a and 30a and rotated together with the rotor 30 to increase the pressure. The relative rotation speed, that is, the hydraulic pressure corresponding to the difference between the rotation speeds of the input shaft 1 and the output shaft 2 is controlled by each pump Occurs indoors. This hydraulic pressure acts between the rotor 30 and the cam ring 31 to suppress the relative rotation between them, so that the rotation speed of the two from the input shaft 1 to the output shaft 2, that is, from one of the front and rear wheels to the other. The driving force corresponding to the difference is transmitted, and the four-wheel drive state is realized. The oil that has been pressurized in each pump chamber is introduced into the bottom of the vanes 30a, 30a through a discharge oil passage 41 that opens to the downstream side in the relative rotation direction, and acts to press the vanes 30a, 30a outward. After that, the communication portion is introduced into the throttle groove 54 through the oil guide hole 42, the annular groove 37, and the communication hole 55, and has an area corresponding to the sliding position of the throttle member 6 as described above. Through the throttle groove 63,
Further, it is introduced into the hollow portion of the pressure plate 32 through the communication hole 64 and the inner cavity of the throttle member 6, and is returned to the oil tank T through the return hole 43. The recirculated oil is sucked into the pump chambers of the vane pump 3 again and used for circulation.

In the above operation, the oil pressure in each pump chamber is generated against the oil flow resistance during the above-described circulation, mainly against the oil flow resistance on the discharge side, and the rate of change of the generated oil pressure with respect to the change in the rotational speed is constant. When the throttle member 6 is slid by energizing the drive coil 7 while the oil resistance increases, the oil passage resistance decreases due to a decrease in the throttle area generated between the throttle groove 54 and the throttle groove 63. Because of the increase, the power transmission characteristic to the output shaft 2 mediated by the hydraulic pressure generated in each pump chamber can be freely changed by adjusting the current supplied to the drive coil 7.

In the device of the present invention, the energization of the drive coil 7 is switched in two ways as described above,
Three kinds of apertures of "medium" and "large" are realized. Of these, when realizing the apertures of "small" and "medium", the aperture member up to the sliding limit position is realized. In addition to the "small" aperture opening requiring the sliding operation of "6", the "middle" aperture opening requiring the intermediate sliding position is also a rough measure of the current supplied to the drive coil 7 as described above. It is surely realized by appropriate adjustment. That is, the energization control unit 10 that controls the energization of the drive coil 7 is only required to perform two rough switching operations based on the detection result of the traveling state, and does not need to perform a complicated control operation. Further, the drive coil 7 is not required to have high accuracy for generating a magnetic field that accurately corresponds to the energizing current, and the above three types of apertures are realized with a simple configuration. It is possible to obtain three corresponding transmission characteristics.

FIG. 4 is a graph showing an example of transmission characteristics realized by the device of the present invention. The horizontal axis in the figure is the rotational speed difference between the front and rear wheels, and the vertical axis is the transmission torque to the output shaft 2. . The solid line in the figure indicates “small” due to the application of a large current to the drive coil 7.
The characteristic in the case where a small aperture area is obtained, the broken line represents the characteristic in the case where the drive coil 7 is not energized and a large aperture area is obtained, and the one-dot chain line The characteristics in the case where a "medium" aperture area is obtained by applying a predetermined current to the respective elements are shown. When the characteristic shown by the solid line is obtained, the input shaft 1 and the output shaft 2 are substantially directly connected, and one of the front and rear wheels is idling due to entry into a snow puddle or a sand puddle, a so-called stack state. Escape from is possible. When the characteristic indicated by the dashed line is obtained, the input shaft 1 and the output shaft 2 are rigidly connected, and a relatively large driving force is transmitted to the other in response to slight slippage occurring on one side. Therefore, stable running on slippery roads such as snowy roads and gravel roads is possible. Further, when the characteristic indicated by the broken line is obtained, a loose connection between the input shaft 1 and the output shaft 2 is obtained, and the difference in the turning trajectory between the front and rear wheels at the time of turning at low speed. The generated rotational speed difference between the two wheels can be absorbed without difficulty, which is effective in preventing the occurrence of tight corner braking. As described above, in the device of the present invention, by controlling the energization of the drive coil 7 by the energization control unit 10 having a simple configuration, three different transmission characteristics can be obtained, and the four-wheel drive state adapted to the traveling state is obtained. Is realized.

In the above description, the coil springs 60a and 60b are arranged in parallel to constitute the biasing spring 60 of the throttle member 6, but as shown in FIG. 5, two springs 60c and 60d having different spring constants are connected in series. The urging spring 60 may be arranged. In this case, by adjusting the current supplied to the drive coil 7, the diaphragm member 6 can maintain an intermediate sliding position in which only the coil spring 60c having a small spring constant is completely shortened, as in the case described above. It is possible to obtain three different transmission characteristics. In this case, however, it is necessary to set the spring constant of the coil spring 60c to be sufficiently larger than that of the other coil spring 60d in order to reliably realize the sliding position.

In any of these embodiments, the number of coil springs forming the biasing spring 60 is not limited to two, and the biasing spring 60 may be configured by three or more coil springs.
In this case, it is possible to select transmission characteristics in more stages.
Further, the arrangement of these coil springs is not limited to the same axis shown in the embodiment, but may be other arrangements such as being arranged around the axis of the throttle member 6 at equal intervals. May be adopted. Further, it goes without saying that the biasing spring 60 may be constituted by a spring other than the coil spring.

FIG. 6 is an enlarged sectional view of a main part of the device of the present invention corresponding to claim 2. In this drawing, the biasing spring 60 for biasing the throttle member 6 is constituted by a single coil spring, while two coils 7a and 7b, each of which can be energized separately, are arranged side by side in the axial direction to form a drive coil. 7, by energizing these coils 7a and 7b, an excitation state of only one of them and both excitation states are created, and two different magnetic fields are generated at the arrangement position of the aperture member 6. , Three different transmission characteristics are realized in addition to the case where both are in the non-excited state. In this case, the energization control unit 10 that controls the energization of the drive coil 7 only needs to have a function of supplying or interrupting the current to the coils 7a and 7b, and cannot have a complicated configuration. Also in this case, the drive coil 7 is composed of three or more coils.
It is needless to say that various kinds of transmission characteristics can be obtained by constructing.

The arrangement positions of the throttle member 6 and the drive coil 7 are not limited to the positions shown in FIG. 1, and may be arranged at any positions on the discharge side of the vane pump 3. However, since the vane pump 3 rotates not only the rotor 30 but also the casing, the arrangement position of the drive coil 7 is limited. The arrangement position of the diaphragm member 6 that moves by the action of the generated magnetic field 7 is also limited.

〔effect〕

As described in detail above, in the device of the present invention, the oil passage resistance on the discharge side of the hydraulic pump, which is disposed on the shaft center of the holding member that rotates together with one of the front and rear wheels, and serves as a medium for transmitting the driving force by its movement. Of the throttle member is biased by a plurality of springs interposed between the throttle member and the holding member, and a magnetic field is applied to the drive solenoid of the throttle member at the position where the throttle member is disposed. Since a plurality of coils forming
A compact structure that does not require space for the spring and coil on both sides of the throttle member, and achieves multiple types of transmission characteristics without causing the solenoid power supply control unit to perform complicated control operations. The present invention has excellent effects, such as being able to improve reliability and contribute to a reduction in product cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the device of the present invention, FIGS. 2 and 3 are enlarged sectional views of main parts thereof, and FIG. 4 is a graph showing an example of transmission characteristics obtained by the device of the present invention. 5 and 6 are enlarged sectional views of a main part showing another embodiment of the device of the present invention. 1 ... input shaft, 2 ... output shaft, 3 ... vane pump, 4
... rotor shaft, 5 ... connecting member, 6 ... throttle member, 7 ...
… Drive coil, 7a, 7b… Coil, 8… Support cylinder, 10…
... Electrification control unit, 30 ... Rotor, 31 ... Cam ring, 50 ...
... holding cylinder, 60 ... biasing spring, 60a, 60b, 60c, 60d ... coil spring

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-93124 (JP, A) JP-A-59-208287 (JP, A) JP-A-63-6284 (JP, A) JP-A-3-3 56721 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F16D 31/00 B60K 17/348 F16K 31/06

Claims (2)

(57) [Claims] 1. A hydraulic pump, which is interposed between a front wheel and a rear wheel and generates a hydraulic pressure corresponding to a rotational speed difference between the two wheels, is disposed on a discharge side of a hydraulic pump. Arranged,
A throttle member that is driven by a solenoid; the action of a magnetic field formed by energizing a drive coil of the solenoid moves the throttle member against the urging of an urging spring; In a four-wheel drive drive coupling device that changes transmission characteristics to front and rear wheels through the hydraulic pressure by adjusting oil resistance, the urging spring is provided between the throttle member and the holding member. A four-wheel drive drive coupling device comprising a plurality of springs interposed and arranged in parallel or in series. 2. A discharge device according to claim 1, wherein said hydraulic pump is provided between said front and rear wheels to generate a hydraulic pressure according to a rotational speed difference between said front and rear wheels. Arranged,
A throttle member driven by a solenoid, wherein the magnetic field formed by energizing a drive coil of the solenoid moves the throttle member against the urging of an urging spring; In the four-wheel drive drive coupling device for changing the transmission characteristics to the front and rear wheels through the hydraulic pressure by adjusting the oil resistance, the drive coils can be individually energized, A drive coupling device for a four-wheel drive, comprising: a plurality of coils arranged in parallel to form a magnetic field including an arrangement position.