JPH0440977Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is a front and rear wheel drive transmission system for a part-time four-wheel drive vehicle that is always two-wheel drive and can be switched to four-wheel drive when necessary. It is related to.

(Prior art) Generally, in a full-time four-wheel drive vehicle, when a rotational difference occurs between the output shaft that transmits driving force to the front wheels and the output shaft that transmits driving force to the rear wheels. A center differential is used that functions to absorb this rotational difference. On the other hand, the above-mentioned part-time four-wheel drive vehicles are often not equipped with the above-mentioned center differential, and therefore suffer from inconveniences such as tight corner braking when making sharp turns in four-wheel drive mode. is likely to occur.

As a countermeasure to this problem, for example, as shown in Japanese Patent Application Laid-Open No. 110533/1982, a shaft that transmits driving force to the front wheels and a shaft that transmits driving force to the rear wheels are adjusted to compensate for the difference in rotation between these two shafts. A drive coupling device has been proposed which is connected by a vane pump that discharges a corresponding amount of oil, and is configured such that the suction port and discharge port of the vane pump are switched depending on the relative rotation direction of the two shafts.

(Problems to be solved by the invention) In the device shown in the above publication, a vane pump is incorporated between the shaft that transmits driving force to the front wheels and the shaft that transmits driving force to the rear wheels. Therefore, the structure is complicated and the durability is low, and the cost increases significantly if the vane pump is used as a drive transmission device for a vehicle.

The present invention aims to solve these problems.

(Means for solving the problems) In order to solve the above problems, the present invention is configured as follows.

First, the front and rear wheel drive transmission device of the present invention has a first output shaft that transmits rotation to the front wheels and rear wheels that are always driven, and a second output shaft that transmits rotation to the wheels that are driven only during four-wheel drive. The present invention includes an output shaft and a sprocket that is disposed on the axis of the second output shaft and to which rotational force is transmitted from the first output shaft through a two-wheel/four-wheel switching mechanism. An inner rotor is rotatably attached to a crank portion eccentric from the rotation axis of the second output shaft. Further, this inner rotor is located in a pump chamber formed on the sprocket side to constitute a trochoid gear pump. Moreover,
In this pump chamber, each hydraulic chamber divided by the inner rotor is communicated with each other by an oil passage. This oil passage is provided with a normally closed check valve that opens when the hydraulic pressure acting there exceeds a predetermined value.

(Function) In the above configuration, during four-wheel drive, the rotation of the first output shaft is transmitted to the second output shaft through the sprocket and the trochoid gear pump. At this time, if the vehicle is running straight on a normal flat road, there will not be a large rotational difference between the front wheels and the rear wheels, so the first output shaft and the second output shaft The shafts rotate almost the same way.

Looking at this with the trochoid gear pump mentioned above, no large torque is generated between its inner rotor and the sprocket in which the pump chamber is formed, and the oil pressure in each hydraulic chamber in the trochoid gear pump is kept low. There is.
Therefore, the oil pressure in the oil passage connecting each hydraulic chamber is also low, and the check valve provided here is closed. Therefore, the inner rotor and the pump chamber rotate together, and the rotation of the sprocket is directly transmitted to the second output shaft.

When the vehicle makes a sharp turn, a rotation difference occurs between the front wheels and the rear wheels, and a rotation difference also occurs between the first output shaft and the second output shaft. In other words, a large torque is generated between the second output shaft and the sprocket, and when looking at this in the case of a trochoid gear pump, a large torque is generated between its inner rotor and the pump chamber, increasing the oil pressure in each hydraulic chamber. I will do it. As a result, a high hydraulic pressure is applied also in the above-mentioned oil passages which communicate the respective hydraulic chambers, and the check valve is opened. As a result, oil flows between each hydraulic chamber of the trochoid gear pump, causing relative rotation between the inner rotor and the pump chamber (i.e., the sprocket), which causes a difference between the second output shaft and the sprocket. It will perform a dynamic function.

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

First, in FIG. 7, which is a cross-sectional view of the auxiliary transmission of a part-time four-wheel drive vehicle, inside the transfer case 1 there is an input shaft 2 which is rotatable and which receives rotational transmission from the main transmission (not shown). It is assembled. A rear output shaft (first output shaft) 3 is also rotatably assembled to the transfer case 1 on the same axis of the input shaft 2. The rotation of the input shaft 2 is transmitted to the rear output shaft 3 through a low/high speed switching mechanism 7. The rotation of the rear output shaft 3 is transmitted to the rear wheels through a companion flange 4 connected to its right end and a propeller shaft (not shown).

A drive sprocket 5 is mounted on the shaft of the rear output shaft 3 so as to be rotatable with respect to the shaft 3. The rotation of the rear output shaft 3 is transmitted to the drive sprocket 5 through a hub sleeve 6 of a two-wheel/four-wheel switching mechanism. Therefore, when the hub sleeve 6 is switched from the illustrated state to the left, rotational transmission from the rear output shaft 3 to the drive sprocket 5 is interrupted.

A front output shaft (second output shaft) 8 is rotatably attached to the trunk floor case 1 in parallel with the rear output shaft 3. A driven sprocket 9 is arranged on the axis of the front output shaft 8 with a trochoid gear pump 20 interposed therebetween, which will be described later. This driven sprocket 9 receives rotational transmission from the rear output shaft 3 through a chain 10 extending between it and the drive sprocket 5. The front output shaft 8 is configured to transmit rotation to the front wheels from the left end in the drawing through a predetermined torque transmission member.

Next, the configuration of the trochoid gear pump 20 will be explained with reference to FIGS. 1 to 6. First, in FIG. 1, which is an enlarged view of a part of FIG. 7, and FIG. 2, which is a cross section taken along the line - in FIG. A crank portion 8a is formed eccentrically from the center. An inner rotor 23 of a trochoid gear pump 20 is attached to the crank part 8a by a bearing 22 so as to be rotatable around the axis of the crank part 8a.

On the other hand, as is clear from FIGS. 3 and 4, which show the driven sprocket 9 alone, the driven sprocket 9 has a pump chamber 2 that houses the inner rotor 23.
6 is formed. A perfectly circular recess 29 is formed on the left side of the driven sprocket 9, and as shown in FIG.
is assembled and fixed to the driven sprocket 9 with a plurality of bolts 25. Further, in the outer peripheral portion of the pump chamber 26 in the driven sprocket 9, a groove-shaped oil passage 27 that continues in the circumferential direction is formed. Moreover, a plurality of bottomed holes 28d are formed on the oil passage 27 at predetermined intervals in the circumferential direction for forming a check valve 28, which will be described later.

As is clear from FIGS. 5 and 6, which show the plate 24 as a single unit, a plurality of communicating passages 27a are formed on the inner surface thereof. When the plate 24 is assembled into the recess 29 of the driven sprocket 9, these communication passages 27a connect the oil passage 27 and each hydraulic chamber 20a partitioned by the inner rotor 23 inside the pump chamber 26, respectively. (See Figure 2). Note that screw holes 28e are formed in the plate 24 at locations corresponding to the bottomed holes 28d of the driven sprocket 9.

Furthermore, a plurality of check valves 28 are constructed in the oil passage 27. This check valve 28 has a spring 28b and a ball 28a installed in each of the bottomed holes 28d formed in the driven sprocket 9, and a plug 28e for holding them inserted into the screw hole on the plate 24 side. 28e. When the oil pressure in the oil passage 27 is below a predetermined value, the ball 28a is pushed up by the spring 28b to the state shown in FIG. The road 27 is blocked.

When the oil pressure acting on the oil passage 27 exceeds a predetermined value, the oil pressure pushes down the ball 28a against the force of the spring 28b, and the check valve 28 opens the oil passage 27. I will do it. In other words, the check valve 28 is a normally closed valve that opens when the hydraulic pressure acting on the oil passage 27 exceeds a predetermined value.

In the front and rear wheel drive transmission device configured as described above, the rotation from the main transmission (not shown) is transmitted from the input shaft 2 to the low/high speed switching mechanism 7 shown in FIG.
The signal is transmitted through the rear output shaft 3 to drive the rear wheels (not shown) as described above. Further, when the hub sleeve 6 of the two-wheel/four-wheel switching mechanism provided on the shaft of the rear output shaft 3 is operated in the state shown in FIG. 7, the rotation of the rear output shaft 3 is controlled by the drive sprocket. It is transmitted through the shaft 5 and the chain 10 to the driven sprocket 9 provided on the axis of the front output shaft 8. The rotation of the driven sprocket 9 is transmitted to the front output shaft 8 through the trochoid gear pump 20, thereby driving the front wheels (not shown).

In this state, when the vehicle is in a four-wheel drive state and the vehicle is traveling straight on a normal flat road, no large rotational difference occurs between the front wheels and the rear wheels. This means that no large rotational difference occurs between the front output shaft 8 and the driven sprocket 9, and when looking at this with the trochoid gear pump 20, there is no large torque between the inner rotor 23 and the pump chamber 26. Does not occur. Therefore, the oil pressure in each hydraulic chamber 20a within the trochoid gear pump 20 is kept low. As a result, each hydraulic chamber 20
Each check valve 28 of the oil passage 27 communicating with the drive sprocket 9 in which the inner rotor 23 and the pump chamber 26 are formed is closed.
The rotation of the driven sprocket 9 is directly transmitted to the front output shaft 8 through the crank portion 8a without causing any relative rotation.

When the vehicle makes a sharp turn, there is a difference in rotation between the front and rear wheels, so the difference between the drive sprocket 9, which is receiving the rotation of the rear output shaft 3, and the front output shaft 8 is A large torque is generated during this time. As a result, the inner rotor 2 of the trochoid gear pump 20
3 and the pump chamber 26, and the hydraulic pressure in each hydraulic chamber 20a increases. Accompanying this, the oil pressure acting on the oil passage 27 also increases, and each check valve 28 provided in the oil passage 27 opens to open the oil passage 27. Therefore, each hydraulic chamber 20a of the trochoid gear pump 20 is in a state of communication through the oil passage 27, and oil is in a state of flowing between each hydraulic chamber 20a. As a result, the inner rotor 23 and the pump chamber 26 can rotate relative to each other, and the front output shaft 8 and driven sprocket 9 rotate differentially, generating a large torque generated by the difference in rotation between the front and rear wheels. absorbs and prevents tight corner braking phenomena.

Note that since the oil level in the transfer case 1 is set higher than the position of the trochoid gear pump 20, the lubricating oil in the transfer case 1 is constantly supplied to each hydraulic chamber 20a in the trochoid gear pump 20. will be replenished.

Furthermore, the elasticity of the springs 28b constituting each of the check valves 28 described above is such that the balls 28 are pushed down at a torque value when a tight corner braking phenomenon occurs due to the difference in rotation between the front wheels and the rear wheels. The differential is set to such a value that the check valve 28 is opened, and the differential function described above is performed only under conditions such as sharp turns.

(Effects of the invention) As described above, the invention has an inner rotor mounted on the crank part eccentric from the rotation axis of the second output shaft, which transmits rotation to the wheels driven only in four-wheel drive. The inner rotor is rotatably assembled and positioned in a pump chamber formed on a sprocket disposed on the axis of the second output shaft to constitute a trochoid gear pump, and furthermore, each of the inner rotors partitioned by the inner rotor in this pump chamber is Four-wheel drive is achieved by communicating the hydraulic chambers with each other through oil passages, and by providing a normally closed check valve that opens when the hydraulic pressure acting on the oil passages exceeds a predetermined value. For example, when the vehicle makes a sharp turn, the operating function can absorb the difference in rotation that occurs between the front and rear wheels, thereby preventing tight corner braking. can. Furthermore, since the above-mentioned differential function is performed by the trochoid gear pump, the present invention has the advantages of a simple structure, excellent durability, and an ability to avoid an increase in cost.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view of the main parts of the front and rear wheel drive transmission device, Fig. 2 is a sectional view taken along the - line in Fig. 1, and Fig. 3 is a sectional view showing only the sprocket in Fig. 1. Figure 4 is a left side view of Figure 3, Figure 5 is a sectional view showing only the plate in Figure 1, and Figure 6 is a left side view of Figure 3.
The figure is a right side view of FIG. 5, and FIG. 7 is a sectional view showing the sub-transmission of a part-time four-wheel drive vehicle. 3... First output shaft, 6... Two-wheel/four-wheel switching mechanism (hub sleeve), 8... Second output shaft, 8a... Crank portion, 9...
Sprocket, 20... Trochoid gear pump,
20a...Hydraulic chamber, 23...Inner rotor, 26...Pump chamber, 27...Oil passage, 28...
Check valve.

Claims (1)

[Scope of utility model registration request] A first output shaft that transmits rotation to a wheel that is always driven among the front wheels and rear wheels, and a second output shaft that transmits rotation to a wheel that is driven only during four-wheel drive.
Front and rear wheels of a part-time four-wheel drive vehicle, comprising an output shaft and a sprocket arranged on the axis of the second output shaft and to which rotational force is transmitted from the first output shaft through a two-wheel/four-wheel switching mechanism. The drive transmission device includes an inner rotor rotatably assembled to a crank portion eccentric from the rotation axis of the second output shaft on the axis of the second output shaft, and the inner rotor is installed in a pump chamber formed on the sprocket side. The hydraulic chambers partitioned by the inner rotor in this pump chamber are communicated with each other by oil passages, and the oil passages are arranged so that the hydraulic pressure acting thereon exceeds a predetermined value. A front and rear wheel drive transmission device for a part-time four-wheel drive vehicle, which is equipped with a normally closed check valve that opens when the vehicle is turned off.