JPH0123331B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a switching control device for a central differential for a vehicle. The device of the invention can be applied to four-wheel drive vehicles equipped with a central differential mechanism.

(Prior Art) In a four-wheel drive vehicle, a switching device is provided that mechanically selects and switches the vehicle drive state between two-wheel drive state, differential four-wheel drive state, and direct four-wheel drive state by manual operation of a shift lever. A power splitting device equipped with this device is disclosed in Japanese Patent Application Laid-Open No. 162334/1983.

(Problems to be Solved by the Invention) However, in the case of the vehicle power split device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 54-162334,
The driving state is switched by manual operation of the shift lever. This switching is not hydraulically controlled, but is controlled entirely by mechanical means.

For this reason, the conventional device is not automatic and is difficult to operate, especially when the vehicle is running.

The present invention automates the conventional manual switching operation described above using a hydraulic control device, thereby facilitating the switching operation.
It is an object of the present invention to provide a power switching control device for a front/rear wheel drive vehicle that can perform the switching quickly.

[Structure of the Invention] (Means for Solving the Problems) The switching control device for a central differential for a vehicle according to the present invention has the following features in order to absorb the difference in rotation between the front wheels and the rear wheels of the vehicle.
A switching control device for controlling the operation of a central differential device disposed between the axles of front and rear wheels, the switching control device extending toward one output shaft side of the central differential device; A first inlet for hydraulic fluid for hydraulic control and a second
an outer wall housing forming a first pressure chamber and a second pressure chamber communicating with the first inlet and the second inlet, respectively, on the inner circumferential side of the inlet; and an inner circumferential surface of the outer wall housing and an axial direction; a first pressure receiving surface that is slidably held in the first pressure chamber and receives pressure in opposite directions in the axial direction by hydraulic pressure in the first pressure chamber and the second pressure chamber; and a second pressure receiving surface that is wider than the first pressure receiving surface. a piston-shaped first movable member, which is slidable in the axial direction with the first movable member, receives pressure in the same direction as the first pressure receiving surface by the hydraulic pressure in the first pressure chamber, and is aligned with the first pressure receiving surface; The third pressure receiving surface has a larger pressure receiving surface than the second pressure receiving surface, and transmits the pressure of the third pressure receiving surface to the first movable member and comes into contact with the outer wall housing at a predetermined position to prevent axial movement. a piston-shaped second movable member to be blocked; a pair of elastic members disposed opposite to the first movable member and having one end fixed to the first movable member; a first engaging portion that is sandwiched between a pair of elastic members and that is driven by the first movable member via the elastic member and that is provided in the casing for the central differential; and the output of the central differential; a movable connecting member having a connecting portion that can selectively engage and disengage with a second engaging portion provided on the shaft and a third engaging portion provided on the drive shaft that engages and disengages with the output shaft; selectively supplying pressure oil to one or both of the inlet and the second inlet, selectively driving the first movable member to one end, the other end, and an intermediate position, and engaging the first engaging portion. The second engaging part, the second engaging part, the third engaging part, and a hydraulic control part for selectively connecting the first, second, and third engaging parts. It is characterized by:

The central differential here refers to full-time 4WD
It is always installed in cars and divides the rotational force from the transmission into the front and rear wheels to drive the front and rear wheels respectively.
At the same time, it is a device that eliminates the difference in rotational speed between the front and rear wheels and transmits smooth rotational force.

A switching control device selectively controls the driving mode of a vehicle between two-wheel driving, differential four-wheel driving, and direct four-wheel driving by controlling the central differential to switch between an active state and a non-active state. The control system includes a hydraulic control circuit and an electrical control circuit.

The output shaft of a central differential gear consists of an output shaft that transmits differential power to the front wheels and an output shaft that transmits power to the rear wheels. be.

The central differential casing rotates when rotational force is transmitted from the input shaft, operating the pinions, side gears, and other elements that make up the differential.
When the rotation of the casing is locked, the rotation of the side gears etc. also stops, and no differential operation occurs.

The first pressure chamber is a chamber that is provided on the inner peripheral surface side of the outer wall housing, communicates with the first inlet, and receives hydraulic fluid and generates operating pressure.

The second pressure chamber is a chamber that is provided on the inner peripheral surface side of the outer wall housing, communicates with the second communication port, and receives the supply of hydraulic oil and generates operating pressure.

The first movable member is a movable member that moves in the direction of the output shaft of the central differential by using the pressure of hydraulic oil that is selectively supplied to the first and second pressure chambers through the first and second inlets of the outer wall housing. It is a piston-like member that is displaced. This first movable member has a first pressure receiving surface facing the first pressure chamber, and a second pressure receiving surface facing the second pressure chamber and wider than the first pressure receiving surface.

The second movable member is an auxiliary piston-like member necessary to move the main first movable member to at least three positions, and the amount of movement changes according to changes in the oil pressure in the first and second pressure chambers. Regulated. The second movable member has a third pressure receiving surface facing the first pressure chamber, and the combined area of the third pressure receiving surface and the first pressure receiving surface is larger than the second pressure receiving surface.
A part of the back surface of the second movable member relative to the third pressure receiving surface faces the first movable member, and transmits the pressure of the third pressure receiving surface to the first movable member, and another part of the back surface When the first movable member is in the intermediate position, it comes into contact with the outer wall housing, thereby preventing the second movable member from moving toward the second pressure chamber.

The elastic member refers to a compression spring or the like, and has a function of transmitting the movement of the first movable member to the movable connecting member, and enables engagement and disengagement between the connecting portion of the movable connecting member and the corresponding engaging portion. This is because it is necessary to constantly apply a load to the movable connecting member.

The movable connecting member is a hub sleeve or the like.

The first engaging portion is a portion such as a dog clutch that can be engaged and disengaged.

The second engaging portion refers to a portion such as a hub clutch that can be engaged and disengaged.

The third engaging portion refers to a portion such as a dog clutch that can be engaged and disengaged.

In the two-wheel driving mode, the movable coupling member moves to the right position, the first engaging part of the casing of the central differential engages with the coupling part of the movable coupling member, and the coupling part of the movable coupling member engages with the first engaging part of the casing of the central differential. The drive shaft is disengaged from the third engagement portion, and power is transmitted only to the other output shaft of the central differential, resulting in a two-wheel drive state.

The differential four-wheel running mode is when the movable connecting member occupies the left position, and at this time, the engagement between the first engaging part of the casing of the central differential and the connecting part of the movable connecting member is disconnected. The sagging casing is rotatable to generate a differential operation, and the connecting portion of the movable connecting member is engaged with the third engaging portion of the drive shaft. Therefore, the driving force is transmitted to the front and rear wheels, and the front and rear wheels are
The difference in rotation between the rear wheels is absorbed.

The direct coupling four-wheel running mode is when the movable coupling member is in the neutral position, and in this case, the coupling portion of the movable coupling portion is in a state of being engaged with the first, second, and third engaging portions, and the casing is Since rotation is prevented, differential operation does not occur, and power is transmitted to the front and rear wheels, driving the four wheels in a directly connected state.

The detection member is a member for confirming whether or not the first movable member has accurately moved to a predetermined position, and is fitted into a recess provided on the circumference of the first movable member. If a positional shift is found as a result of the detection, the detection result is input to the hydraulic pressure control section, and the hydraulic pressure is adjusted.

The driving mode changeover switch is operated by a button or the like, and inputs the above-described switching between two-wheel driving, differential four-wheel driving, and direct-coupling four-wheel driving as an electric signal to the above-mentioned electric control circuit. .

(Function) According to the configuration of the present invention, the hydraulic control section selectively supplies hydraulic oil to one or both of the first pressure chamber and the second pressure chamber through the first inlet and the second inlet, The first movable member and the second movable member can be moved in the axial direction using hydraulic pressure applied to each pressure receiving surface of the first movable member and the second movable member. Here, the first pressure receiving surface of the first movable member and the third pressure receiving surface of the second movable member receive the pressure of the first pressure chamber, and the pressure of the second movable member receives the pressure of the first movable member. This is the second pressure receiving surface. Since the second movable member contacts the outer wall housing at a predetermined position, movement toward the second pressure chamber is restricted. Therefore, the force that displaces the first movable member toward the second pressure chamber is the hydraulic pressure applied to the first pressure receiving surface and the third pressure receiving surface until the second movable member comes into contact with the housing; After the first pressure-receiving surface contacts the housing, only the first pressure-receiving surface receives hydraulic pressure.
On the other hand, the force that displaces the first movable member toward the first pressure chamber is the hydraulic pressure applied to the second pressure receiving surface. Here, the area of each pressure receiving surface has a magnitude relationship of (first pressure receiving surface) < (second pressure receiving surface) < (first pressure receiving surface + third pressure receiving surface), and therefore the hydraulic pressure that each pressure receiving surface receives This relationship also applies to the size of . Therefore, the first and second
When hydraulic oil is supplied to both pressure chambers, the first movable member is held at the predetermined position, that is, the intermediate position. In addition, when hydraulic oil is supplied to only one pressure chamber, the hydraulic pressure acts only on the pressure receiving surface of the one side, so the first movable member is pushed to the other side and held at one end or the other end. . The operation of the first movable member that is selectively driven to one end, the other end, and an intermediate position as described above is transmitted to the movable connecting member for switching control via the elastic member. As a result, the movable coupling portion moves to three positions, and the coupling portion provided on the movable coupling member selectively engages and disengages from the corresponding engagement portion provided on the output shaft of the central differential. These three positions are for 2-wheel driving mode, differential 4
Since it is predetermined to correspond to the wheel running mode and the direct four-wheel running mode, it is possible to switch to the three running modes according to the displacement of the movable member. This switching operation can be performed freely by simply operating a changeover switch connected to the electric control circuit of the hydraulic control section.

(Embodiments of the Invention) An embodiment of a switching control device according to the present invention will be described with reference to the drawings. A schematic diagram of the entire power transmission system of an automobile including the switching control device of the present invention is shown in FIG.

Power from the engine 1 is transmitted via a clutch 2 and a transmission 3 to an input shaft 5 of a transfer device 4 that performs a power distribution function. A dog clutch device 6 is integrally connected to the input shaft 5, and the clutch sleeve 7 is selectively moved by operating a T/F lever (not shown), and by moving to the left, the clutch sleeve 7 is moved to the left. The gears are arranged so that in the state shown in the figure, the gear is neutral, and by moving to the right a high speed gear can be obtained.

The power transmitted to the output gear 9 via the intermediate gear 8 is distributed to output shafts 11 and 12 by a central differential 10 that is integrally connected to the output gear. A hub clutch 13, which is a second engaging portion, is integrally connected to the tip of the output shaft 11. A dog clutch 15 is connected to the end of the casing 14 of the central differential as a first engaging part, a dog clutch 17 is connected to the front wheel drive shaft 16 as a third engaging part, and a movable connecting member 18 consisting of a hub sleeve is connected to the end. It is installed so that it can be connected to and removed from the section.

The detailed structure of the central differential 10 and the switching control device according to the present invention is shown in FIG. 2, and the movable coupling member 1
8 is shown in FIGS. 3 and 4.

The movable elastic member 18 is configured to be held by elastic members 21 and 22 installed on the inner peripheral side of the first movable member 20 housed in the housing 19.
In this way, the movable connecting member 18 is connected to the first movable member 20.
is moved in the moving direction via elastic members 21 and 22.

FIG. 2 shows a state in which the movable coupling member 18 is in a neutral position. In this case, the coupling portion of the movable coupling member 18 is connected to the dog clutch 15 of the casing 14, the hub clutch 13 of the output shaft 11, and the dog clutch 17 of the drive shaft 16. Since they are respectively engaged, the central differential device 10 does not perform differential operation, and power is transmitted to the front and rear wheel drive shafts, resulting in a direct four-wheel drive mode.

When the movable coupling member 18 moves leftward from the state shown in FIG. 2 to the position shown in FIG.
However, since the dog clutch 15 of the casing 14 is disengaged, the casing 14
is rotatable and the side gear 23 of the central differential
a and 23b (FIG. 2) are in a differentially enabled state. On the other hand, the power is distributed to the output shafts 11 and 12, and a differential four-wheel driving mode is obtained.

Next, when the movable connecting member 18 moves rightward from the neutral position shown in FIG. 2, it becomes the state shown in FIG. 4. In this case, the connecting portion of the movable connecting portion 18 is connected to the dog clutch 15 of the casing 14 and the output shaft 11.
The drive shaft 16 is engaged with the dog clutch 13, while the drive shaft 16 is disengaged from the dog clutch 17. In this state, power is not transmitted to the drive shaft 16, and since the casing 14 is integrally engaged with the output shaft 11, no differential operation occurs and the two-wheel drive mode is established.

Here, the functions of the first movable member 20 and the second movable member 24 that move the movable connecting member 18 will be explained.

The first movable member 20 and the second movable member 24 housed in the outer wall housing 19 are supplied with a first pressure chamber 250a from a pressure source (not shown) through a first inlet 25a and a second inlet 25b. Second pressure chamber 2
Hydraulic oil is supplied to 50b. In the state shown in FIG. 2, the first inlet port and the second inlet port 25a, 25
b to the first pressure chamber 250a and the second pressure chamber 250
b both are in a state where hydraulic oil is supplied, and the hydraulic oil acts on the first movable member 20 from the left and right,
The first pressure receiving surface 26c of the first movable member 20, the second pressure receiving surface 26b wider than this, and the second movable member 24
The combined pressure receiving area of the first pressure receiving surface 26c and the third pressure receiving surface 26d is larger than that of the second pressure receiving surface 26b. Second pressure chamber 25
Looking at the force relationship of the hydraulic pressure inside 0b, in the state shown in FIG.
The second pressure receiving surface 2 has the largest force pressed against the second pressure receiving surface 25a and receives hydraulic oil from the second inlet 25b.
The first pressure receiving surface 26 receives hydraulic oil from the first inlet 25a.
The relationship is such that the hydraulic pressure to c is next in line. Therefore, the first movable member 20 is maintained at the neutral position. Note that 25c is a discharge port for hydraulic oil when the first and second movable members move.

When the first movable member 20 moves to the right, the supply of hydraulic oil from the second introduction port 25b to the second pressure chamber 250b is cut off, and the supply of hydraulic oil from the first introduction port 25a to the first pressure chamber 250b is interrupted.
Hydraulic oil is supplied only to 50a. Moreover, when the first movable member 20 moves to the left, the first introduction port 25a
The supply of hydraulic oil to the first pressure chamber 250a is cut off, and the supply of hydraulic oil from the second inlet port 25b to the second pressure chamber 250b
only to be refueled.

Three recesses (grooves) were bored on the circumference of the first movable member 20 at predetermined pitches. These recesses 27a, 27b, and 27c are the movable connecting member 1.
They are provided at the same pitch as the displacement amount of 8, and the tip of the detection member 28 is fitted therein. This detection member 28 checks whether the first movable member 20, the movable coupling member 18, etc. are maintained in the state as instructed by the electric control circuit 41 (FIG. 6) including the travel mode changeover switch, and checks whether or not the first movable member 20, the movable coupling member 18, etc. It has the function of sending a signal to the electric control circuit 41 (FIG. 6). In addition, in order to effectively use the power for driving the oil pump (described later), the hydraulic oil is turned on and off by the output of the detection member mentioned above according to instructions from the electric control circuit 41 (Fig. 6). did.

Elastic members 21 and 2 that hold the movable connecting member 18
2, when moving the movable coupling member 18 from right to left or left to right, a load is constantly applied to the movable coupling member 18 in order to assist the coupling portion of the movable coupling member 18 and the dog clutches 15 and 17 to mesh smoothly. This is because it is necessary to add the following.

A schematic diagram of a hydraulic control circuit for feeding hydraulic oil to the first inlet 25a (first pressure chamber 250a) and the second inlet 25b (second pressure chamber 250b) is shown in FIG.
As shown in the figure.

The oil discharged from the oil pump 29 is configured to be conducted to the inlet ports 25a and 25b through a pressure regulating valve 30, a check valve 31, and change valves 33 and 34. In the state shown in FIG. 5, both the solenoid valves 35 and 36 are closed, so the constant pressure regulated by the pressure regulating valve 30 is applied to the change valves 33 and 34 through the orifices 37 and 38. Since these are pressed against the springs 39 and 40, the hydraulic oil is conducted to the inlet ports 25a and 25b. In this state, the power transmission system is in the state shown in FIG. 2, that is, in the direct four-wheel drive mode.

When the solenoid valve 36 is opened (ON) in the state shown in FIG. 5, the hydraulic oil that has passed through the orifice 38 is discharged by the solenoid valve 36, so the change valve 34 is moved to the right by the spring 40. and the oil supply to 25b is cut off. Therefore, the first and second movable members 20 and 24 are supplied with hydraulic oil from the first inlet 25a, and the first and second movable members 20 and 24 are moved to the right as shown in FIG. A state of engagement occurs. That is, the mode is switched to two-wheel driving mode.

Conversely, if the solenoid valve 35 is opened (ON), the meshing state shown in FIG. 3 will be established, and the mode will be switched to the differential four-wheel drive mode.

FIG. 6 shows a flowchart illustrating the outline of switching to each driving mode (two wheels, differential four wheels, direct four wheels). In the figure, the input signals to the electric control circuit 41 include each changeover switch (2-wheel drive switch, differential 4-wheel drive switch, direct connection 4-wheel drive switch) (not shown) that is operated and selected by a person. 1 a detection member 28 that detects the movement of the movable member 20;
and a T/F position detecting member (not shown) (used to automatically switch to direct-coupling four-wheel mode when the gear is in low gear). The output signals from the electric control circuit 41 include a signal for operating the solenoid valves 35 and 36, and an indicator lamp signal for recognizing the direct four-wheel running state and the differential four-wheel running state. Further, the oil discharged from the oil pump 29 passes through the pressure regulating valve 30 and is communicated with the inlet ports 25a and 25b via the solenoid valves 35 and 36.
5 and 36 are configured to be turned on and off by respective operation switch sensors (not shown).

[Effects of the Invention] In the switching control device according to the present invention, the force that displaces the first movable member toward the second pressure chamber is restricted from moving toward the second pressure chamber when the second movable member is in a predetermined position. Until then, the hydraulic pressure is received by the first pressure receiving surface and the third pressure receiving surface, and after the second movable member is regulated at the predetermined position, the hydraulic pressure is received only by the first pressure receiving surface, and each pressure receiving surface The hydraulic pressure that the surface receives is configured to have a magnitude relationship of (first pressure receiving surface)<(second pressure receiving surface)<(first pressure receiving surface+third pressure receiving surface). Therefore, the hydraulic control unit controls the first pressure chamber and the second pressure chamber through the first inlet and the second inlet.
When hydraulic oil is supplied to both pressure chambers, the first movable member can be held at the predetermined position, that is, at the intermediate position, and when hydraulic oil is supplied to only one pressure chamber, the first movable member The member can be held at one end or the other while being pushed to the other side. Further, in the control device of the present invention, the areas (pressure receiving surfaces) of the left and right pressure chambers that make the first movable member movable are different, and the second movable member is provided in the larger pressure chamber, and the second movable member A stopper is formed on the end face of the outer housing for preventing axial movement of the housing. Therefore, in the switching control device of the present invention,
The first movable member can be arbitrarily controlled in three steps only by controlling the supply and disconnection of hydraulic oil at a constant hydraulic pressure without changing the hydraulic pressure. Since the operation of the first movable member is transmitted to the movable connecting member via the elastic member, the movable connecting member
It is possible to switch to three predetermined positions corresponding to two-wheel drive mode, differential four-wheel drive mode, and direct-coupled four-wheel drive mode.

Therefore, according to the present invention, each driving mode of two-wheel driving, differential four-wheel driving, and direct-coupling four-wheel driving is achieved by utilizing the connecting and disconnecting actions of the movable connecting member controlled by the hydraulic control section. Among them, switching can be done automatically and quickly with just a simple switch operation. Therefore, it is possible to improve driving operability, starting performance, rough road performance, fuel efficiency, etc. Moreover, the switching control device as a whole is compact and has a simple configuration, so reliable operation can be obtained, and it can be manufactured at low cost and easily, and the device can be easily maintained.

[Brief explanation of drawings]

FIG. 1 is a skeletal diagram illustrating the entire power transmission system including a switching control device according to the present invention. FIG. 2 is a sectional view showing the detailed structure of the embodiment of the present invention, and FIGS. 3 and 4 are enlarged sectional views showing the mode of operation of the embodiment of the invention. FIG. 5 is a hydraulic control circuit diagram used in an embodiment of the present invention;
The figure is a flowchart illustrating the outline of driving mode switching in an embodiment of the present invention. 10... Central differential gear, 11, 12... Output shaft, 1
3... Hub clutch (second engagement part), 14... Casing of central differential gear, 15... Dog clutch (first engagement part), 16... Drive shaft, 17... Dog clutch (third engagement part), 18... Movable Connecting member, 19...
Outer wall housing, 20...first movable member, 21, 2
2... Elastic member, 24... Second movable member, 25a... First inlet, 25b... Second inlet, 25c... Discharge port, 26c... First pressure receiving surface, 26b... Second pressure receiving surface,
26d...Third pressure receiving surface, 27a, 27b, 27c...
recess, 28... detection member, 29... oil pump, 3
0... Pressure regulating valve, 31... Check valve, 33... First change valve, 34... Second change valve, 35... First solenoid valve, 36... Second solenoid valve, 41... Electric control circuit, 250a... First pressure chamber , 250b...second pressure chamber.

Claims (1)

[Claims] 1. In order to absorb the rotation difference between the front wheels and rear wheels of the vehicle,
A switching control device for controlling the operation of a central differential device disposed between the axles of front and rear wheels, the switching control device extending toward one output shaft side of the central differential device; A first inlet for hydraulic fluid for hydraulic control and a second
an outer wall housing that forms a first pressure chamber and a second pressure chamber communicating with the first inlet and the second inlet, respectively, on the inner peripheral surface side of the inlet; a first pressure receiving surface that is slidably held in the first pressure chamber and receives pressure in opposite directions in the axial direction by hydraulic pressure in the first pressure chamber and the second pressure chamber; and a second pressure receiving surface that is wider than the first pressure receiving surface. a piston-shaped first movable member, which is slidable in the axial direction with the first movable member, receives pressure in the same direction as the first pressure receiving surface by the hydraulic pressure in the first pressure chamber, and is aligned with the first pressure receiving surface; The third pressure receiving surface has a larger pressure receiving surface than the second pressure receiving surface, and transmits the pressure of the third pressure receiving surface to the first movable member and abuts against the outer wall housing at a predetermined position to prevent axial movement. a piston-shaped second movable member to be blocked; and a piston-shaped second movable member disposed opposite to the first movable member, one end of which is connected to the first movable member.
A pair of elastic members fixed to a movable member, and a pair of elastic members sandwiched between the elastic members,
The first movable member is driven by a first engaging portion provided on the central differential casing, a second engaging portion provided on the output shaft of the central differential, and a second engaging portion provided on the output shaft of the central differential. a movable connecting member having a connecting part that can selectively engage and disengage with a third engaging part provided on the drive shaft to be engaged and disengaged; and pressurized oil in one and both of the first inlet and the second inlet. selectively supplies the first movable member to one end, the other end, and an intermediate position, and selectively drives the first movable member to one end, the other end, and an intermediate position, and 1. A switching control device for a central differential for a vehicle, comprising three engaging portions and a hydraulic control portion for selectively connecting the first, second, and third engaging portions. 2 The movable connecting member has a connecting portion that is connected to the first
By engaging and disengaging from the engaging portion, the central differential is locked and unlocked, and when the connecting portion engages and disengages from the second and third engaging portions, power is connected and A switching control device for a central differential for a vehicle according to claim 1, which performs disconnection. 3. The one end, the other end, and the intermediate position of the first movable member correspond to a two-wheel driving mode, a differential four-wheel driving mode, and a direct-coupling four-wheel driving mode, respectively. Central differential switching control device. 4. The first movable member has at least three recesses formed on the circumference corresponding to the positions occupied by the movable connecting member, and the outer wall housing has a position detecting member that can be fitted into the recesses. A central differential for a vehicle according to claim 1, further comprising a member. 5 The hydraulic control section includes an oil pump, a pressure regulating valve,
A check valve, a first check valve and a second check valve communicating with the first inlet and the second inlet of the outer wall housing, and first and second solenoid valves, and the linked operation of these valves. According to
a hydraulic control circuit that selectively supplies and shuts off the hydraulic oil to the first inlet and the second inlet;
Claim 1 further comprises an electric control circuit that supplies an electric signal in response to operation of a travel mode changeover switch or the like to control the operation of the first and second solenoids constituting the hydraulic control circuit. Switching control device for central differential for vehicles.