JPH032690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention provides a switching device for two-wheel and four-wheel drive;
The present invention relates to a power transmission device for an automobile having an auxiliary transmission device capable of switching between high and low speed drive.

(Prior art) Recently, in order to adapt automobiles to various driving conditions, the power transmission system connecting the engine and wheels has been switched between two-wheel drive (front and rear) and four-wheel drive (front and rear). The actuator for this switching operation is a diaphragm type actuator that operates with the engine's intake negative pressure and thereby performs the above switching (for example, the actuator for this switching operation). Publication No. 59-114132).

Furthermore, when attempting to select the four-wheel drive state, it is desirable to increase the transmitted torque because the vehicle is usually traveling on a rough road such as sand or mud. Therefore, some power transmission systems are provided with a sub-transmission device that enables the wheels on the drive side to be switched from a high-speed drive state to a low-speed drive state.

In the above configuration, when the two-wheel drive state is set to a low-speed drive state, the large transmission torque described above is transmitted only to the two driven wheels. However, this places an excessive load on the power transmission system connecting the engine and the wheels. For this reason, conventionally, a detection means has been provided for detecting that the sub-transmission has selected the low-speed drive state, and a detection signal from the detection means operates the actuator to switch to the four-wheel drive state, thereby increasing the transmission torque. There is one that distributes the transmission to four wheels.

(Problems to be Solved by the Invention) By the way, since the above-mentioned actuator uses air pressure, due to the compressibility of air, fluid resistance, etc., it is difficult to input the detection signal from the detection means. There is a time delay, albeit a small one, in the operation until the switching operation to the wheel drive state is completed. Therefore, immediately after the auxiliary transmission selects the low-speed drive state, the switching device maintains the two-wheel drive state, and therefore a large transmission torque is loaded on the power transmission system connecting the engine and the two driven wheels. This is not desirable.

(Object of the Invention) This invention was made in view of the above-mentioned circumstances, and when the sub-transmission is switched to a low-speed drive state, a large transmission torque from the engine is transmitted to one of the front and rear wheels. The purpose is to prevent the inconvenience of being transmitted only to one wheel side and applying a large load to the transmission system.

(Structure of the Invention) A feature of the present invention for achieving the above object is that a detection signal from the detection means indicating that the sub-transmission device has released the high-speed drive state causes the switching device to
The point is that the actuator is actuated to switch to a wheel drive state.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 is a car, and this car 1 has a drive device 2,
It has a front wheel device 3 and a rear wheel device 4 driven by this drive device 2.

The drive device 2 has an engine 6 and a main transmission 6' connected to the engine 6. A carburetor 7 is connected to the intake side of the engine 6.

To explain the front wheel device 3, 13,1
3 is a front wheel, and a pair of left and right front axles 14, 14 are connected to each of the front wheels 13, 13, respectively. Further, a front wheel differential device 15 is provided between the front axles 14, 14. This front wheel differential device 15 is a known one, and the drive pinion 1 on the input side
6 and a pair of left and right differential side gears 1 on the output side
7, 17, and these differential side gears 17, 1
It has a ring gear 18 that rotates coaxially with the drive pinion 7 and meshes with the drive pinion 16.

To explain the rear wheel device 4, like the front wheel device 3, this rear wheel device 4 is composed of a pair of left and right rear wheels 19, 19, rear axles 20, 20, and a rear wheel differential device 21. The wheel differential 21 has a drive pinion 22 .

The engine 6 and front and rear wheel differentials 15 and 2
1 through a transfer 24. This transfer 24 switches the power of the engine 6 between high speed and low speed and transmits it only to the rear wheels 19, 19, or in addition to this, also transmits it to the front wheels 13, 13.

The transfer 24 will be explained in more detail.

This transfer 24 includes an input shaft 25 that receives power from the engine 6, a front wheel output shaft 27 connected to a drive pinion 16 of a front wheel differential 15 via a front wheel propulsion shaft 26, and a rear wheel propulsion shaft. Drive pinion 2 of rear wheel differential 21 via 28
2 and a rear wheel output shaft 29 provided coaxially with the input shaft 25.

The transferor 24 has a switching device 30 that can switch between a two-wheel drive state (front or rear) or a four-wheel drive state (front or rear), and also switches the drive side wheels between a high-speed drive state and a low-speed drive state. It has an auxiliary transmission device 31 that can be switched to either state.

First, the sub-transmission device 31 will be explained. This sub-transmission device 31 includes the main transmission device 6'.
The front wheel differential device 15 further decelerates the rotation from
This auxiliary transmission 31 has a transmission shaft 32 provided corresponding to the input shaft 25 and the output shaft 29 for the rear wheels.
have. An input gear 33 is freely rotatably provided on the input shaft 25, and this input gear 33
A first reduction gear 34 is supported on the speed change shaft 32 so as to mesh with the transmission shaft 32 . In addition, a second
A reduction gear 35 is supported, and this second reduction gear 35
An output gear 36 is freely rotatably provided on the rear wheel output shaft 29 so as to mesh with the rear wheel output shaft 29.

An engager 38 is provided on the input shaft 25 so as to be slidable in the axial direction. This engaging element 38 is movable in the axial direction via a manual shift lever (not shown), and by its axial movement, the input shaft 25 and the rear wheel output shaft 29 are directly connected, or the input shaft 25 and the rear wheel output shaft 29 are directly connected.
5 and the input gear 33 are connected. 39 is a chain transmission means, and this chain transmission means 39 connects the output gear 36 and the front wheel output shaft 27.

Further, the switching device 30 is provided with a transfer clutch 40 that connects and disconnects power transmission from the rear wheel output shaft 29 to the output gear 36.

Then, as shown by the solid line in the figure, the above-mentioned engager 38
When the input shaft 25 and the rear wheel output shaft 29 are connected by operating the transfer clutch 40 and the rear wheel output shaft 29 and the output gear 36 are disconnected by operating the transfer clutch 40, the power of the engine 6 is transferred at high speed. Rear wheel differential device 2
1 to only the rear wheels 19, 19. That is, this is a high-speed two-wheel drive state.

Connect the input shaft 25 and the rear wheel output shaft 29 by operating the engaging element 38 (shown by a solid line in the figure), and
When the transfer clutch 40 is operated to connect the rear wheel output shaft 29 and the output gear 36 (shown by a chain double-dashed line in the figure), the power of the engine 6 is transferred at high speed to the rear wheel via the rear wheel differential 21. The power of the engine 6 is transmitted to the front wheels 13, 13 via the front wheel differential 15. That is, this is a high-speed four-wheel drive state.

In addition, as shown by the two-dot chain line in the figure, the same engager 3
8 to connect the input shaft 25 and the input gear 33, and operate the transfer clutch 40 to connect the rear wheel output shaft 29 and the output gear 36, first, the power of the input shaft 25 is Each gear 33-36
The decelerated power is transmitted to the front and rear wheels 13 and 19 via the front and rear wheel differentials 15 and 21. That is, this is a low-speed four-wheel drive state.

A diaphragm type transfer actuator 42 is provided for connecting and disconnecting the transfer clutch 40. In the transfer actuator 42, one chamber 42a partitioned off by a diaphragm is communicated with the atmosphere via a first on-off valve 43. This first on-off valve 43 has 3 ports 2
It is a position solenoid valve, and the solid line shows the state where the solenoid is off (OFF), and the two-dot chain line shows the state where the solenoid is on. In this first on-off valve 43, one of the chambers 4
A third port other than the ports connected to 2a and the atmosphere side, respectively, is connected via a check valve 44 to the downstream side of the carburetor 7, that is, to a location where the intake negative pressure of the engine 6 is high.

Further, the other chamber 42b of the transfer actuator 42 is connected to the downstream side of the carburetor 7 via a second on-off valve 46. This second on-off valve 46 has the same configuration as the first on-off valve 43, and its third port communicates with the atmosphere.

And, normally, the first on-off valve 43 and the second on-off valve 4
6 are both turned on, and one chamber 42a of the transfer actuator 42 is communicated with the downstream side of the carburetor 7 by this first on-off valve 43 to have a negative pressure. The other chamber 42b of the yuator 42 is communicated with the atmosphere through a second on-off valve 46, and the transfer actuator 42 is operated by the pressure difference between them. In conjunction with the transfer actuator 42, the transfer clutch 40 cuts off the power transmission from the rear wheel output shaft 29 to the output gear 36 (shown by a solid line in the figure). In this way, the two-wheel drive state described above can be obtained.

Moreover, contrary to the above, if both the first on-off valve 43 and the second on-off valve 46 are turned off, one chamber 42a of the transfer actuator 42 is communicated with the atmosphere side, and the other The chamber 42b is connected to the downstream side of the vaporizer 7 and has a negative pressure, and the transfer actuator 42 is actuated by the differential pressure. In conjunction with the transfer actuator 42, the transfer clutch 40 connects the rear wheel output shaft 29 and the output gear 36 (shown by a two-dot chain line in the figure). In this way, the four-wheel drive state described above can be obtained.

Next, an electrical device for switching between the two-wheel drive state and the four-wheel drive state will be explained.

48 is a power supply, and this power supply 48 is connected to a selector switch 4.
9 is connected. The changeover switch 49 is a switch for selecting between two-wheel drive (2WD) and four-wheel drive (4WD), and has a two-wheel drive contact 49a and a four-wheel drive contact 49b. And above 2
A first on-off valve 43 and a second on-off valve 46 are connected to the wheel drive contact 49a.

On the other hand, when the transfer clutch 40 is operated to establish a four-wheel drive state, a limit switch 51 detects the operation of the transfer clutch 40.
will be provided. This limit switch 51 has a normally open contact 51a, and is turned on when the above-mentioned four-wheel drive state is detected. Further, 52 is an indicator light for indicating the four-wheel drive state, and the contact point 5 is
1a and this indicator light 52 are connected in series to the power source 48.

Then, when the two-wheel drive contact 49a is connected to the power source 48 by operating the changeover switch 49, both the first on-off valve 43 and the second on-off valve 46 are turned on. 42 operates the transfer clutch 40 to disconnect the rear wheel output shaft 29 and the output gear 36, and the rear wheel 1
The power of engine 6 is transmitted only to 9 and 19, and 2
Wheel drive condition is obtained. In this case, the contact 51a of the limit switch 51 is turned off (shown by the solid line in the figure), so the indicator light 52 is turned off. On the other hand, by operating the changeover switch 49, the four-wheel drive contact 4
When 9b is connected to the power source 48, the first on-off valve 43
and the second on-off valve 46 are both turned off, whereby the transfer actuator 42 operates the transfer clutch 40 to close the rear wheel output shaft 2.
9 and the output gear 36, and the rear wheels 19, 19
In addition, the power of the engine 6 is transmitted to the front wheels 13, 13, resulting in four-wheel drive. In this case, the contact 51a of the limit switch 51 is turned on (as shown by the two-dot chain line in the figure), so the indicator light 52 lights up to indicate that the vehicle is in four-wheel drive mode.

In the above configuration, a device is provided to prevent the vehicle from entering the two-wheel drive state when the sub-transmission device 31 is brought into the low-speed drive state.

This device will be explained below.

Reference numeral 54 denotes a limit switch, and this limit switch 54 is a detection means for detecting the switching state of the sub-transmission device 31 from a high-speed drive state to a low-speed drive state, and this detection is performed by detecting the operation of the engaging element 38. The limit switch 54 has a high speed contact 54a and a low speed contact 54b,
The high speed contact 54a is connected to the power supply 48 and the changeover switch 49.
The low speed contact 54b is interposed between the power supply 48 and the contact 51a of the limit switch 51.
is interposed between.

When the engaging element 38 connects the input shaft 25 and the output shaft 29 for rear wheels to bring the sub-transmission device 31 into a high-speed state, it engages with the engaging element 38 and turns on the high-speed contact 54a. (Solid line in the figure). on the other hand,
When the engaging element 38 connects the input shaft 25 and the input gear 33 to bring the auxiliary transmission 31 into a low speed state, it engages with the engaging element 38 and turns on the low speed contact 54b (two points in the figure). (Dotted line shown). Furthermore, at the time of transition between the high-speed drive state and the low-speed drive state, each power transmission between the input shaft 25 and the output shaft 29 for the rear wheels, and between the input shaft 25 and the output shaft 29 for the rear wheels is disconnected, and the transmission of power between the input shaft 25 and the output shaft 29 for the rear wheels is disconnected. The gong 38 is placed in a neutral state. In this case, the engagement with the engaging element 38 is released, and both the high-speed contact 54a and the low-speed contact 54b are turned off (indicated by a chain line in the figure).

Therefore, when the sub-transmission device 31 is in the high-speed drive state, that is, when the high-speed contact 54a is on, the two-wheel and four-wheel drive states can be changed by operating the changeover switch 49. freely chosen. On the other hand, when the sub-transmission device 31 is in a low-speed driving state, that is, the high-speed contact 54
When a is off, both the first on-off valve 43 and the second on-off valve 46 are off, regardless of the switching operation of the changeover switch 49, and the transfer actuator 42 interlocked therewith changes the four-wheel drive state. becomes.

Furthermore, when the sub-transmission device 31 cancels the high-speed drive state, the high-speed contact 54a is immediately turned off, so as described above, both the first on-off valve 43 and the second on-off valve 46 are turned off, and the associated transfer valve is turned off. The actuator 42 brings the vehicle into a four-wheel drive state.

(Effects of the Invention) According to the present invention, the actuator is actuated so that the switching device switches to the four-wheel drive state in response to a detection signal from the detection means indicating that the sub-transmission device has released the high-speed drive state. When changing from a state to a low-speed drive state, the switching operation by the actuator to the four-wheel drive state is started from the moment the high-speed drive state is canceled. Therefore,
Even if it takes some time from the start to the completion of the switching operation of the actuator to change from the two-wheel drive state to the four-wheel drive state, within the time required to switch from the high-speed drive state to the low-speed drive state, The switching operation of the actuator can be completed. Therefore, when the auxiliary transmission is switched to a low-speed drive state, the large transmission torque from the engine caused by the low-speed drive state is transmitted only to the two driven wheels, creating a large load on the power transmission system. The occurrence of the inconvenience of giving

[Brief explanation of the drawing]

The figure is an overall view showing an embodiment of the invention. 1...Car, 6...Engine, 13,13...Front wheel, 19,19...Rear wheel, 24...Transfer, 3
0...Switching device, 31...Sub-transmission device, 42...Transfer actuator (actuator).

Claims (1)

[Claims] 1 The power transmission system that connects the engine and the front and rear wheels is equipped with a switching device that can switch between two-wheel drive (front and rear) and four-wheel drive (front and rear), and the wheels to be driven are driven at high speeds. A power vehicle for an automobile, which is provided with an auxiliary transmission capable of switching between a driving state and a low-speed driving state, an actuator for switching the switching device, and a detection means for detecting the switching state of the auxiliary transmission. A power transmission device for an automobile, characterized in that the transmission device operates an actuator so that the switching device switches to a four-wheel drive state in response to a detection signal from the detection means indicating that the sub-transmission device has released the high-speed drive state. .