JPS63176730A - Four-wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To enable an engine to be prevented from its blow up resulting from a center differential gear, by providing a free wheel clutch which avoids driven running of a propeller shaft in a two-wheel-drive driven side driving system when a vehicle is in two-wheel driving operation. CONSTITUTION:A spline wheel 19 is provided integrally being juxtaposed in the second side gear 17, and a free-lock switching sleeve 21, which can move reciprocating between a differential free position, engaging only with a spline 20 of a differential case, and a differential lock position engaging with both the spline 20 and the spline wheel 19 of the differential case, is provided between the spline 20 and the spline wheel 19 formed in the periphery in the rear end part of the differential case 13. The switching sleeve 21 is actuated by a shift fork 23 operated being associated with movement of an operating actuator 22 of a two and four-wheel driving switching mechanism 2, and a center differential lock-free switching mechanism 3 is constituted of these described sleeve, shift fork, actuator and mechanism.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a four-wheel drive system, and particularly includes a center differential that can switch between a two-wheel drive state and a four-wheel drive state, and absorbs the difference in rotational speed between the front wheels and rear wheels in the four-wheel drive state. related to things.

[Conventional technology]

In a four-wheel drive vehicle, a so-called center differential (hereinafter simply referred to as a differential) is provided in order to avoid a braking phenomenon when turning and to achieve neutral steering to improve steering performance. This center differential is functionally equivalent to a front differential or a rear differential, and first transmits the rotational output from the transmission to the differential case, and also has a pair of side gears that simultaneously mesh with a pinion that is rotatably supported by the trunnion shaft of this differential case. One of them (the differential side gear for front wheel drive) is connected to the front wheel drive system, and the other (the differential side gear for rear wheel drive) is connected to the rear wheel drive system. This center differential distributes driving force to the front wheels and rear wheels so that the rotation speed of the differential case becomes the average rotation speed of the front wheels and the average rotation speed of the rear wheels. As a result, while transmitting driving force from all wheels to the road surface, it is possible to absorb the difference in rotational speed between the front and rear wheels during a turn and avoid braking phenomena. Furthermore, since driving force can be appropriately distributed to all wheels, steering performance can be dramatically improved, approaching neutral steering. Furthermore, recently, even though the four-wheel drive vehicle has a center differential as described above, it can be switched between a four-wheel drive state (hereinafter simply referred to as the four-part state) and a two-wheel drive state (hereinafter simply referred to as the two-part state) as needed. All four-wheel drive vehicles are now equipped with selectable switches. For example, when switching between a two-wheel drive mode that drives only the rear wheels and a four-wheel drive mode that drives all four wheels, the two-wheel drive/four-wheel drive switching mechanism can connect and disconnect the front wheel drive differential side gear of the center differential from the front wheel drive system. In addition, the system switches between a differential function state (center differential free state) in which the differential case and the front wheel drive differential side gear can rotate relative to each other, and a center differential free state in which the differential case and the front wheel drive differential side gear prevent relative rotation. A center differential lock/free switching mechanism is added. In the two-part state, the two-wheel drive/four-wheel drive switching mechanism disconnects the front wheel drive differential side gear from the front wheel drive system, and the center differential lock/free switching mechanism selects the center differential lock state. In the four-wheel drive state, the two-wheel drive/four-wheel drive switching mechanism connects the front wheel drive differential side gear and the front wheel drive system, and the center differential lock/free switching mechanism selects the center differential free state. The reason for the addition of the center flop mechanism is as follows.
If the center differential is not locked, the front wheel drive differential side gear will be in a free state in the two-part condition, and only this front wheel drive differential side gear will idle, resulting in the engine revving up. When the center float mechanism is in the differential function state, the pinion cannot rotate, so the differential case and the pair of side gears rotate together. In the two-part state, the front wheel drive differential side gear is disconnected from the front wheel drive system, so the engine rotational output transmitted to the differential case is directly transmitted to the rear wheel drive system via the rear wheel drive differential side gear. It happens. In addition, in order to avoid the above-mentioned racing, when transitioning between the 2-part state and the 4-part state, a state fLi is established in which the 2-part/4WD switching mechanism assumes the 4-part state and the center differential lock mechanism assumes the center differential lock state. It is necessary to go through In addition, the center differential lock mechanism is used, for example, when off-roading, when either the front or rear wheels are spinning, the front wheel drive system and the rear wheel drive system are forcibly connected directly by a switch operation to escape from the mud. etc. can be made to function. Furthermore, in a two-part state, for example, in a state where only the rear wheels are driven, one side gear of the front differential is connected to one side gear of the front differential in order to prevent mechanical loss or vibration and noise caused by the driven rotation of the propeller shaft of the front wheel drive system. A freewheel clutch is interposed between this and the axle shaft to be connected, and this freewheel clutch is locked when the vehicle is in the four-part state (axle lock state) and free when the vehicle is in the two-part state* <Axle free state). If this freewheel clutch is set to a free state when it is in a two-part state, even if the side gear on the side that is directly connected to the wheel rotates following the wheel, the side gear on the freewheel side will simply idle in the opposite direction and the differential case will be closed. does not rotate. Therefore, the front propeller shaft, which has a relatively large mass, is not rotated when in the two-part state, and mechanical loss is reduced accordingly, and vibrations and the like are avoided.

[Problems to be solved by the invention]

By the way, the above freewheel clutch is t 1ffl
, because it is operated in conjunction with the operation of the 2-part/4-wheel drive switching mechanism, there is a slight delay in its operation with respect to the operation of the 8-part/4-wheel drive switching mechanism, which causes the engine to rev up. There is concern that it may cause In other words, when switching from a 4-part state to a 2-part state, the 2-part/4WD switching mechanism fails to switch to the 2-part state first, and even if the freewheel clutch becomes free after this, the front There is no problem because the transmission of driving force to the propeller shaft is blocked.
If the locking operation of the freewheel clutch is too delayed when switching from the two-part state to the four-part state, the freewheel clutch side gear of the front differential will simply spin idle even if driving force is transmitted to the front propeller shaft, resulting in a no-load state. appears, causing the engine to rev up. Once the engine revs up like this, the freewheel clutch shifts to a locked state while the side gear is idling at high speed, and when this clutch engages, impact torque is applied to the drive system. So I don't like it. This invention was devised under the above circumstances.
Operates in conjunction with the two-part/four-wheel drive switching mechanism between the center differential, the two-part/four-wheel drive switching mechanism, and either the front or rear axle that is driven in the two-part state and the differential to which that axle is linked. An object of the present invention is to prevent engine revving when changing from a two-part state to a four-part state in a four-wheel drive vehicle equipped with a freewheel clutch.

[Means to solve the problem]

In order to solve the above problem, the present invention takes the following technical measures. That is, the four-wheel drive vehicle of the present invention includes a differential case to which the rotation of the output shaft of the transmission is transmitted, a pinion rotatably supported on the trunnion shaft of the differential case, and a pair of side gears that mesh with the pinion at the same time. a center differential provided therein; a constant drive system for one of the front wheels or rear wheels connected to a first side gear among the side gears; and a constant drive system for one of the front wheels or rear wheels connected to a second side gear among the side gears. Interposed between the other two-wheel drive driven side drive system and the second side gear connected to the two-wheel drive driven side drive system, and operates the two-wheel drive/four-wheel drive changeover switch. By this, it is possible to switch between a two-drive state in which the second side gear and the two-part driven side drive system are cut off, and a four-part state in which the second side gear and the two-part driven drive system are connected. Interlocking with the operation of the above-mentioned two-part/west-side switching mechanism, there is a center differential lock state in which the differential case and the second side gear cannot rotate relative to each other when in the two-part state, and the above-mentioned when in the four-part state. a center differential-free switching mechanism that operates to switch between a center differential free state that allows the differential case and the second side gear to rotate relative to each other; and a differential of the two-part driven side drive system and one axle extending from the differential. A double-acting actuator, which is interposed between the shafts and operates using negative pressure as an energy source in conjunction with the operation of the two-part/west side switching mechanism, isolates the differential between the differential and the axle shaft when in the two-part state. a freewheel clutch that switches between an axle-free state in which the two-part/west side switching mechanism is in the four-part state and an axle-locked state in which the differential and the axle shaft are connected when the four-part state is in the four-part state; In addition, a detection switch is further provided to detect that the switch has not been switched to the axle free operation side of the actuator that drives the freewheel clutch when the 2nd/west side selector switch is switched from the 2nd position to the 4th position. The actuating pneumatic circuit of the actuator is configured to communicate the axle-free operation side compartment of the actuator with the atmosphere when the detection switch detects the four-part state by applying pressure to the actuator.

[Effect]

When the two-part/west side switching mechanism takes the four-part state, the second side gear and the two-part driven side drive system are connected, and the center differential lock/free mechanism selects the center differential free state. Therefore, the center differential functions, and the power from the transmission is distributed and transmitted from the first side gear to the constant drive system and from the second side gear to the two-part driven side drive system. At this time, since the freewheel clutch locks the driven side drive system at the two-part axle, engine revving does not occur. When attempting to shift the two-part/west side switching mechanism from the four-part state to the two-part state, first, the center differential lock/free mechanism selects the center differential lock state, and then the second side gear and the two-part driven side drive system select the center differential lock state. transitions to a two-part state in which is blocked. Therefore, during this switching, the center differential will not be blown up forcefully. Then, in conjunction with these F force operations, the freewheel clutch switches to the axle-free state (G). Therefore, in the two-part state, the propeller shaft on the driven side does not follow the wheel and idle. No. In addition, before the freewheel clutch switches to the axle free state, the second part/west side switching 4!L side cuts off power transmission to the driven side drive system, so engine revving will not occur. No. Here, a supplementary explanation of the meaning of operating the freewheel clutch in conjunction with the operation of the two-part/west side switching mechanism is as follows.For example, if the freewheel clutch is operated in conjunction with the operation of the two-part/west side switching mechanism, If it is operated in conjunction with the west side changeover switch, the freewheel clutch will first change from the axle lock state to the axle free state before the two-part/west side changeover mechanism actually shifts from the four-part state to the two-part state. If such a concern were to become a reality, the axle would become free while the driving force is being transmitted to the driven side front propeller shaft via the center differential, and the front differential would In order to avoid such a situation where the engine revs up due to a no-load condition, the axle freewheel is basically operated in conjunction with the operation of the two-part/west side switching elfI. On the other hand, when attempting to shift the 2-part/west side switching mechanism from the 8-part state to the 4-part state, first the second side gear and the second-part driven drive system are connected, and then the center differential lock/free is connected. The mechanism selects the center differential free state, and the free wheel clutch switches from the axle free state to the axle lock state in conjunction with the operation of the two-part/west side switching mechanism.Here, the two-part/four-wheel drive switching mechanism selects the four-part/west side switching mechanism. If there is too much time lag between the freewheel clutch switching to the axle lock state and the freewheel clutch switching to the axle lock state, the freewheel clutch switching to the axle lock state will cause the center differential lock/free switching mechanism to switch to the center differential free state. However, in the present invention, the switching action of the freewheel clutch from the axle locked state to the axle free state is accelerated as follows. In other words, when the indoor 2-part/4-wheel-drive switching remote switch is switched from the 2-position iη to the 4-position position, the axle lock operating side branch of the actuator that drives the freewheel clutch is activated. When a detection switch detects that the two-part/four-wheel drive switching mechanism has switched to the four-part state by applying negative pressure, the axle-free operating side branch of the actuator is communicated with the atmosphere. It is. In the two-part state, the freewheel clutch is in the axle-free state, so negative pressure is acting on the actuator in its axle-free side chamber. Therefore, when the 2-part/4-wheel drive remote switch is turned to the 4-part position and negative pressure is applied to the axle lock side compartment of the actuator, the actuator is currently in a state where negative pressure is applied to both of its compartments. put out However, as a matter of course, a detent a is provided on the freewheel clutch side to hold the axle in the free position. Then, when the detection switch detects that the two-part/four-wheel drive switching mechanism has actually switched to the four-part state, the axle-free operation side compartment is opened to the atmosphere. At this time, it is tightened so that negative pressure acts only on the axle lock activation side compartment, and the actuator switches the freewheel clutch to the axle lock side. In this way, in the present invention, one of the chambers is opened to the atmosphere after passing through the quasi-c6 stage in which negative pressure is applied to both chambers of the actuator, so that the negative pressure acting on one chamber is transferred to the other chamber. Compared to the general method of reconnecting to a separate compartment, the pipe friction resistance of the pneumatic circuit system during switching is overwhelmingly small, and therefore, the freewheel clutch axle is activated after the -F detection switch detects the four-part condition. This dramatically speeds up the transition to the locked state. For this reason, when transitioning from the two-part state to the four-part state, the center differential free/lock switching mechanism becomes the differential free state.
In (2), the freewheel clutch can be reliably switched to the axle-open state, and engine revving can be reliably avoided at this time.

[Effect] As a result of the above, we have a center differential, a two-part/four-wheel drive switching mechanism, and a freewheel clutch that avoids the driven rotation of the propeller shaft of the driven side drive system when the two-part is in the second-part. In both cases, when switching from a two-part state to a four-part state, and when switching from a four-part state to a two-part state, engine revving caused by the center differential and driven side drive during two-part A four-wheel drive vehicle that secures a high level of integrity of the drive power transmission system while reliably avoiding engine revving caused by system differentials and reducing mechanical loss, vibration, and noise during driving. is achieved.

[Explanation of Examples]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows the overall configuration of a four-wheel drive vehicle according to the present invention, and FIGS. 2 to 6 show a vehicle equipped with a center differential 1, a two-part/four-wheel drive switching mechanism 2, and a center differential lock/free switching mechanism 3. The specific configuration of the transfer 5 is shown below. In addition,
These figures show an example in which the rear wheels are driven when the vehicle is in the second position, that is, the i; I wheel drive system becomes the driven side drive system when the vehicle is in the second position. Therefore, in the following explanation, the rear wheel drive system 6
The term "front wheel drive system 7" refers to the constant drive system mentioned in "Means for Solving the Problem", and the term "front wheel drive system 7" refers to the two-part driven drive system. In addition, each of these figures from FIG. 1 to FIG. 6 shows the four-part B, that is, the center differential lock/free switching mechanism 3 is in the center differential free state, and is attached near the differential 8 in the front wheel drive system 7. A case is shown in which the freewheel clutch 9 is in the axle lock state. The transfer 5 is attached to the engine 10 and the transmission 11 following them. A differential case 13 of the center differential 1 is supported so as not to be relatively rotatable on an output shaft 12 that introduces the output of the transmission 11 into the transfer. The interior of the differential case 13 includes a pinion 15 rotatably supported by a trunnion shaft 14, and a first side gear 16 and a second side gear 17 that mesh with the pinion 15 at the same time. The first side gear 16 is rotatably supported at the rear of the output shaft 12 and coaxially therewith, and is fixed to the front end of the export force shaft 18, and the second side gear 17 is
Thereafter, it is supported on the outer periphery of the export force shaft 18 so as to be relatively rotatable. Then, a spline wheel 19 having the same outer diameter as the differential case 3 is integrally installed in the second side gear 17, and a spline 20 formed on the outer periphery of the rear end of the differential case 13 and the spline wheel 19 As shown in Fig. 1, there is a spline 20 of the differential case between the
A free/lock switching sleeve 21 is provided that can reciprocate between a differential free position where it engages only the differential case and a differential lock position where it engages both the splines 20 of the differential case and the spline wheel 19. This switching sleeve 21 has a shift fork 23 that is operated in conjunction with the movement of an actuator 22 for operating a two-part/four-wheel drive switching mechanism 2, which will be described later.
These components constitute the center differential lock/free switching mechanism 3. A front wheel drive gear 25 is integrally attached with a spline wheel 24 having the same diameter as the spline wheel 19 adjacent to the rear of the spline wheel 19 on the rear export force shaft 18.
is supported for relative rotation. On the other hand, on the side of the rear export force shaft 19, a front export force shaft 26 is rotatably supported in parallel thereto, and between an output gear 27 fixed to this and the front wheel drive gear 25, By turning 28, the rotation of the front wheel drive gear 25 is transmitted to the front export force shaft 26. Further, between the spline wheel 19 and the spline wheel 24, as shown in FIGS. 1 and 3, both spline wheels 19.
A two-part/four-wheel drive switching sleeve 29 that can reciprocate between a four-part position where it engages with the spline wheel 24 and a two-part position where it only engages with the spline wheel 19 is slidably coupled. The two-part/four-wheel drive switching sleeve 29 is driven by a shift fork 30 that is reciprocated by the actuator 22, thereby configuring the two-part/four-wheel drive switching mechanism 2. The details of the interlocking mechanisms of the two-part/four-wheel-drive switching mechanism 2 and the center-front/free switching mechanism 3 and their operations will be described later. The rear end of the rear export force shaft 18 is connected to the rear propeller shaft 3
1. Rear wheel 34 via rear differential 32 and rear axle 33
It is connected to. The front end of the front export force shaft 26 is connected to a front end 37 via a front propeller shaft 35, a front differential 8, and a front axle 36, and one axle is connected to the front end 37 at an intermediate portion thereof. It is separated into a portion 36a connected to one side gear and a portion 36b connected to the wheel 37, and a freewheel clutch mechanism 9 is interposed between these. This freewheel clutch mechanism 9 has spline wheels 38, 39 of the same diameter fixed to the ends of each part 363, 36b of the axle, and has an axle lock position in which one engages with the other, and an axle lock position in which one engages with the other. A switching sleeve 40 that can reciprocate between an axle-free position where only the axle is engaged is fitted therein. The switching sleeve 40 is actuated by a switching fork 42 driven by an actuator 41. Next, the two-part/four-wheel drive switching mechanism 2 and the center differential lock/
The details of the interlocking mechanism of the free mechanism 3 will be explained. As clearly shown in FIGS. 2 and 4, a slide shaft 43 parallel to the rear export force shaft 18 is supported in the upper part of the transfer housing. This slide shaft 43 is reciprocated in the axial direction by the actuator 22. An interlocking boke 45 is integrally fixed to the intermediate portion of this slide shaft 43 for transmitting its movement to a switching boke 42 of the center differential lock/free switching mechanism 3, which will be described later, via a rocking crank 44. , one end of the swing crank 44 is engaged with the arm portion 44a. Therefore, this linking boke 45 moves in the axial direction of the slide shaft 43 as one body, and the swing crank 4
4 also responds directly to the movement of the slide shaft 43. Then, on the rear side of the linking boke 45 on the slide shaft 43, the proximal end boss portion of the shift boke 30 for the two-part/four-wheel drive switching sleeve described above is fitted so as to be freely slidable in the axial direction. Further, this shift balk 30 connects a generally U-shaped plate member 46 in a plan view, which is slidably connected to the slide shaft 43 at the rear part of the shift balk 30 and one part of the connecting balk 45. It is always urged forward by urging it forward by a compression coil spring 47 which is attached to the front part of the body. That is, the shift balk 30 is connected to the slide shaft 4.
When 3 slides backward, it is pushed directly,
When the slide shaft 43 moves forward, it is not directly pushed. In addition, in the figure, when the shift balk 30 is located at the rear, it is in the four-position position;
When it is located in front, it is in a dual position. On the other hand, a locking lever 49 extending forward is attached to the side surface of the base boss portion 30a of the shift boke 30 via a pin 48.
is rotatably attached, and this locking lever 49 is always biased in a direction overlapping the slide shaft 43 by hooking one end of the compression coil spring 47. This locking lever 49 is connected to the shift balk 3o.
Dimensions are set so that when the tip is at the rear part on the slide shaft 43, that is, at the four-part position, the tip is stretched against the rear surface of the latching step part 52 provided in the continuous part of the transfer housing. Further, a slanted cam surface 50 is formed on one side of the locking lever 49, and a guide pin 51 protruding from the linking boke 45 is engaged with this cam surface 50. ing. From the above, when the slide shaft 43 or the connecting bokeh 45 moves forward, that is, in the direction of the second position, the guide pin 51 pushes the cam surface 50 of the locking lever 49 to the side and moves the locking lever 49 in the direction indicated by the arrow. However, while the tip of the locking lever 49 is pushed against the rear surface of the locking step 52, the two parts W of the shift balk 30 are rotated in the direction W.
Movement to the side will be blocked. During this time, since the slide shaft 43 is still being moved in the direction of the two-part position by the action of the actuator 22, the compression coil spring 47 is accumulating energy. Then, the locking lever 49 is further rotated to release the tension between its tip and the locking stepped portion 52, allowing the shift baulk 30 to move toward the second position, and the compression coil spring It is moved to the dual position by the accumulated power of 47. When the shift balk 30 is moving to the latching position, the tip of the latching lever 49 is caught on the side wall of the latching step 52, as shown by the imaginary line in FIG. Contrary to the above, when the slide shaft 43 moves from the two-part position to the four-part position,
As previously mentioned, the shift balk 30 is moved directly toward the fourth position. At this time, the tip of the locking lever 49, whose tip was hooked on the side wall of the locking step 52, is pulled against the rear wall of the locking step 52 as shown in FIG. 6 by the biasing force of the spring 47. Return to position and rotate. On the other hand, near the slide shaft 43 of the two-part/four-wheel drive switching mechanism 2, a support shaft 53 is fixed parallel to the slide shaft 43 with the swing crank 44 in between. A base boss portion 23a of a shift boke 23 for moving the switching sleeve 21 of the center differential lock/free switching mechanism 3 described above is slidably fitted onto the support shaft 53. The shift boke 23 has one end fixed to the rear end of the support shaft 53 and a front end between the tip of the U-shaped temporary member 54 arranged so as to insert the tip of the boss portion 23a. A compression coil spring 55 interposed in the shape of a tone is always biased forward, that is, in the direction of the free position. Furthermore, on the support shaft 53, there is a shift balk 23 with "-"
An interlocking sleeve 56 is slidably fitted adjacent to the rear of the boss portion 23a. The other end arm portion 44b of the above-mentioned three-movement crank 44 is engaged with this linkage sleeve 56, and therefore, the movement of the slide shaft 43 of the two-part/four-wheel drive switching mechanism is controlled by the linkage balk 45, the swing Via the crank 44, it is first transmitted to this link sleeve 56 and moved. Then, in this linking sleeve 56,
A retaining piece 57 that integrally extends from the lift box 23 is formed with an abutting portion 56a that can be hooked from the front, and this linking sleeve 56 is connected from the front to the rear, that is,
When moving from the free position toward the locked position, the contact portion 5
6a and the engagement piece 57, the shift boke 23 in the front free position is forcibly moved to the rear lock position against the elasticity of the compression coil spring 55. The base boss portion 23a of the shift balk 23 further includes:
As shown in FIG. 5, a cylindrical portion 59 is formed in which an engaging body 58 having a tapered tip 60 is accommodated, and the tip of the engaging body 58 is always elastically attached to the circumferential surface of the support shaft 53. It is urged by a spring 61 so as to be pressed against it. Further, at least the rear part of the inner periphery of the proximal end boss part 23a from the engaging body 58 is enlarged in diameter so that the front end part of the linking sleeve 56 can enter therein, and a cylindrical shape is formed between the base end boss part 23a and the support shaft 53. A space is formed. On the other hand, on the circumferential surface of the support shaft 53, a non-chill 2 is provided around which the protruding end 60 of the engaging body 5 can engage when the shift boke 23 slides rearward, that is, to the lock position. Therefore, the shift boke 23, which has been slid to the rear lock position against the compression coil spring 55 like a double series, is moved by the engagement body 5's tip 6o automatically engaging the notch 62. held in cocked position. Conversely, when the link sleeve 56 moves from the lock position direction to the free position direction, that is, from the rear to the front, its front end enters into the enlarged diameter part of the proximal end boss part of the shift boke 23 and engages the engagement body 58 and the notch 62. The shift boke 23 will be held at the locked position until it is disengaged from the shift boke 23. When the engagement body 58 and the notch 62 are disengaged in this manner, the shift boke 23 returns to the free position by the stored force of the compression coil spring 55. The linkage between the two-part/four-wheel drive switching mechanism 2 and the center differential lock/free switching mechanism 3 described above can be summarized as follows. Assume that the two-part/four-wheel drive switching mechanism 2 is now in the four-part state. At this time, the center differential lock/free switching mechanism 3 is in a free state. That is, the slide shaft 43 or the switching balk 42 is at the rear four position, and the shift balk 23 of the support shaft 53'' is at the front free position. When the actuator 22 operates and the slide shaft 43 moves in the direction of the second position, the linking balk 45, the swinging crank 44, or the linking sleeve 56 on the center differential lock/free switching mechanism side
move in direct conjunction with each other, but the switching balk 42 does not move yet because the locking lever 49 is stretched against the rear surface of the locking step 52. On the other hand, due to the movement of the swing crank 44, the center differential lock free mechanism side The linking sleeve 56 can directly move the shift balk 23 to the differential lock position by forcibly pushing the engagement piece 57 of the shift balk 23 with its contact portion 56a. Then, when the center differential L is locked, the locking lever 49 that is stretched against the rear surface of the locking step 52 on the two-part/four-wheel drive switching mechanism side moves the guide pin 51 as the slide shaft 43 moves. The tension relationship is released, and at this time, the switching balk 42 is slid to the forward two-position position by the M force of the compression coil spring 47. Conversely, the actuator 22 operates to move the slide shaft 4.
When 3 moves from the front two-part position to the rear four-part position,
The switching balk 42 is moved in the four-way direction by being directly pushed by the linking balk 45. At this time, the rocking crank 44 and the linking sleeve 56 move in direct conjunction, but as described above, the shift boke 23 on the center differential lock/free switching mechanism side still remains in the differential lock due to mutual engagement between the engaging body 58 and the notch 62. remains held in position. Then, when the connecting sleeve 56 further moves toward the free position and its front end forcibly releases the engagement between the engaging body 58 and the notch 62, the shift boke 23 is moved by the compression coil spring 5.
It is moved to the differential free position by the M force of 5. In other words, when transitioning from a four-part state to a two-part state, and from a two-part state to a four-part state, the vehicle always goes through a four-part state in which the center differential is locked. In this example, a delay means 63 is further provided to delay the switching operation from the differential lock state to the differential free state in the center differential lock/free switching mechanism. That is, as shown in FIGS. 2 to 4, the bushing rod 64 connects to the center differential lock/free switching mechanism, for example, an orifice-type damper 65 configured to suppress the retracting speed of the punosoyurosod 64. 3, so as to protrude toward the outer surface of the shift balk 23, and on the other hand, in the continuous part of the shift balk 23,
A sloped cam 66 is formed, which is tilted toward the front, and the tip of the bushing rod 64 comes into sliding contact. In this way, the shift balk 23 can move from the differential free position to the differential lock position independently of the damper 65, while when moving from the differential lock position to the differential free position by the force of the compression coil spring 55, the inclined cam 23 can move from the differential lock position to the differential lock position.
6 moves while compressing the bushing rod 64, its movement is decelerated. Next, a transfer actuator 22 for operating the two-part/four-wheel drive switching mechanism 2, a freewheel actuator 41 for axle lock/free switching of the front wheel drive system 7, and a pneumatic system unique to the present invention related to these. The circuit will be explained. In this example, these actuators 22.41 are constructed of diaphragm type double-acting actuators, which are driven by the differential pressure between the negative pressure of the engine and atmospheric pressure. As shown in FIG. 1, the transfer actuator 22
is operated by a combination of a four-part on-off valve 67 and a two-part on-off valve 68, each consisting of a three-boat, two-position solenoid valve connected to the negative pressure of the engine. The suction boat of the four-part on-off valve 67 is communicated with the four-part side compartment 22 a of the transfer actuator 22 , and the suction boat of the two-part on-off valve 68 is communicated with the second-part side compartment 22 b of the transfer actuator 22 . That is, when negative pressure is applied to the fourth part side compartment 22a, the slide shaft 43 is moved to the fourth part position side, and the second part side compartment 22a is moved to the fourth part position side.
When negative pressure acts on 2b, the slide shaft 43 is moved to the second position. Further, the four-part on-off valve 67 is switched so that the suction boat is opened when the solenoid is not energized, and negative pressure is applied to the suction boat when the solenoid is energized. Conversely, the two-wheel drive on-off valve 68 is switched so that negative pressure acts on the suction boat when the solenoid is not energized, and the suction boat is opened to the atmosphere when the solenoid is energized. Furthermore, the freewheel actuator 41 is similarly operated by a combination of an axle lock on-off valve 69 and an axle free on-off valve 70, which are connected to the negative pressure of the engine and are composed of a 3-port, 2-position solenoid valve. . The suction boat for the axle lock on-off valve 69 is. Lock side compartment 41 of freewheel actuator 41
a, and the suction boat of the axle free on-off valve 70 is communicated with the free side compartment 41b of the freewheel actuator 41. That is, when negative pressure acts on the lock-side compartment 41a, this actuator moves the switching sleeve 40 to the 7x lock side.
When the axle is moved and negative pressure is applied to the free side compartment 41b, the switching sleeve 40 is moved to the axle free side. In addition, the axle lock on-off valve 6
9 is switched so that negative pressure acts on the suction boat when the solenoid is not energized, and when the solenoid is energized, the suction boat is opened to the atmosphere. Conversely, the axle-free on-off valve 70 is switched so that when the solenoid is not energized by 1ffl, the suction boat is open to the atmosphere, and when the solenoid is energized, negative pressure is applied to the suction boat. The solenoids of the four-part on-off valve 67 and the two-part on-off valve 68 are both connected via a line 72 to a four-part side contact 73 of a two-part/four-part remote changeover switch 71 disposed in, for example, a console box. . Further, the solenoid of the axle lock on-off valve 69 is connected to the second side contact 75 of the changeover switch 71 via a line 74. Further, this changeover switch 71 is connected to a power source 76.
It has reached this point. Furthermore, in the middle part of the line 77 connecting the line 72 and the line 74, a portion between a pair of diodes 78 and 79 arranged opposite each other detects that the two-part/four-wheel drive switching mechanism 2 has been switched to the west side state. The positive side terminal of a two-part/four-wheel drive changeover detection switch 80 arranged in the transfer 5 is connected to the four-part negative contact 81 of this switch 80.
is connected to ground via a four-part status indicator lamp 82. Furthermore, the solenoid of the axle free on-off valve 70 is
It is connected to the electric fi 76 via a normally closed relay 83 which is opened when power is applied between the four-side negative contact 81 of the switch 80 and the indicator lamp 82. The two-part/four-wheel drive changeover detection switch 80 is, for example, a switch that is closed by the movement of the slide shaft 43 from the second-part position to the fourth-part position in the two-part/four-wheel drive switching mechanism. can do. Next, the operation of the four-wheel drive vehicle of this example having the above configuration will be explained. In this state, as shown in FIG. 1, the solenoids of the four-part on-off valve 67 and the two-part on-off valve 68 are energized, so as mentioned above, negative pressure acts on the suction boat of the former 67. , the suction boat of the latter 68 is open to atmospheric pressure. Therefore, transfer actuator 2
Negative pressure acts on the four-way side compartment 22a of No. 2, and the slide shaft 43 of the two-part/four-wheel drive switching mechanism 2 is located at the rear, that is, on the four-part position side. In addition, the center differential lock/free switching mechanism 3 is the two-part/four-wheel drive switching mechanism 2 described above.
It is located at the differential free position depending on the position of the slide shaft 43. At the same time, it is detected that the slide shaft 43 is in the four-section position, the two-section/four-wheel-drive changeover detection switch 8° is closed to the four-section negative contact, and the four-section status display lamp 82 is lit. Furthermore, the coil of the normally closed relay 83 is connected to the detection switch 80.
Since current flows from the negative contact 81 on the fourth side of the relay 83, this relay 83 is opened and the axle free on-off valve 70
The solenoid is not energized. Furthermore, the solenoid of the axle lock on-off valve 69 is not energized. The axle lock on/off valve 69 applies negative pressure to the suction boat when the solenoid is de-energized, and the axle free on-off valve 70 allows the suction boat to be opened to the atmosphere when the solenoid is de-energized. Negative pressure acts only on the lock-side compartment 41a of the actuator 41, so that the switching sleeve 40 of the freewheel clutch 9 is in the lock position and connects the front axle 36 and the front differential 8. In this state, a four-wheel drive state appears in which the center differential 1 functions while the rotational difference between the front wheel drive system 6 and the rear wheel drive system 7 can be absorbed. 2nd part / 4WD switching switch, cheer 1 is 4th part 1! When the switching is made from the first to the second part side, first, the energization to the solenoids of the four part on-off valve 67 and the two part on-off valve 68 is cut off. Then, the speaker port of the four-part on-off valve 67 is opened to the atmosphere, and negative pressure acts on the suction port of the two-part on-off valve 68, so negative pressure acts on the two-part side chamber of the transfer actuator 22, causing it to slide. The shaft 43 is moved forward, that is, to the second part side. At the same time, the line 74 is energized and the solenoid of the axle lock on-off valve 69 is energized.
The suction boat is opened to the atmosphere. Therefore, in this state, equal atmospheric pressure acts on both the chambers 41a and 41b of the freewheel actuator 41, but due to the holding mechanism such as the detent mechanism,
The switching balk 42 and/or the switching sleeve 40 are still held in the locked position. As described above, until the slide shaft 43 is moved to the second section side, the second section/four-wheel drive changeover detection switch 80 is still closed to the fourth section side, so the axle free on-off valve 70 is still in a de-energized state. As described above, equal atmospheric pressure acts on both compartments of the actuator 41, but when the slide shaft 43 moves to the second part side and the detection switch 80 is opened, the coil of the normally closed relay 83 The relay 83 is closed and the solenoid of the axle free on-off valve 70 is energized. Therefore, at this time, negative pressure acts on the suction boat of the on-off valve 70, and as a result,
Negative pressure acts only on the free side compartment 41b of the actuator 41, and the freewheel clutch 9 is switched to the free state. In addition, the two-part/four-wheel drive switching mechanism 2 in the transfer
The center pfloat free mechanism 3 is connected,
As described above, the vehicle moves from the four-part center differential free state to the two-part center differential locked state via the four-part center defrot state, and the racing in the center differential is avoided. When the 2-part/4-wheel drive changeover switch 71 is switched from the 2-part side to the 4-part side, first, the solenoids of the 4-part on-off valve 67 and the 2-part on-off valve 68 are energized, and only the 4-part side compartment 22a of the transfer actuator 22 is energized. The negative pressure acts to move the slide shaft 43 rearward toward the four-position position. At the same time, aTi from the line 74 to the solenoid of the axle lock on-off valve 69 is cut off. That is, after the switch 71 is switched to the four-layer side until the slide shaft 43 is completely moved to the four-layer position, the suction ports of both the axle lock on-off valve 69 and the axle free on-off valve 70 are closed. Negative pressure acts on both compartments of the freewheel actuator 4. However, the detent mechanism holds the switching sleeve 40 on the free side. Then, when the -1-2 slide shaft 43 moves completely to the fourth section side, the second section/four-wheel drive changeover detection switch 80 is closed, the coil of the normally closed relay 83 is energized, and this relay 83 is opened. death,
Power to the solenoid of the axle-free on-off valve 70 is cut off. At this point, the intake port of the on-off valve 70 is opened to the atmosphere, and negative pressure acts on the actuator 41 only in its lock-side compartment 41a, so that the freewheel clutch 9 becomes locked. In this case, the freewheel actuator 41 is switched by following a unique procedure of first passing through a standby stage in which negative pressure is applied to both compartments 41a and 41b, and then opening the actuator free side compartment 41b to the atmosphere. Therefore, compared to reapplying negative pressure from one branch chamber 41b to the other branch chamber 41a, the pipe friction loss of the pneumatic pipeline at the time of switching is reduced, and the operating time is dramatically shortened. It is. In the transfer 5, the interlocking mechanism moves the slide shaft 43 completely from the second position to the fourth position, and then the center differential lock/free switching mechanism 3 is moved.
The shift balk 23 is moved from the differential lock position to the differential free position by the force of the compression coil spring 55.
As mentioned above, due to the rapid switching of the actuator 41 of the freewheel clutch 9, the switching from the axle free state to the axle free state is delayed by the switching of the center differential lock/free switching mechanism 3 to the differential free position. This prevents the engine from revving up at this time. Of course, the scope of the invention is not limited to the duplicate embodiments. The type of each actuator or the pneumatic circuit for operating it can be modified in various ways in addition to the embodiments. Moreover, although the embodiment is an example in which the rear wheels are driven all the time and the front wheels are driven part-time, it is also possible to drive the front wheels all the time and drive the rear wheels part-time. In this case, the rear export force shaft of the embodiment is connected to the front wheels, and the front export force shaft is connected to the rear wheels. l! All you have to do is make a design change to connect them. In the embodiment, a means for delaying the switching operation of the center differential lock/free switching vA structure from the center differential lock state to the center differential free state is provided, but whether or not to install this means is a matter of choice. .

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an embodiment of a four-wheel drive vehicle according to the present invention, Fig. 2 is a sectional view of the transfer seen from the rear of the above embodiment, and Fig. 3 is taken along the line ■-■ in Fig. 2. 4 is an enlarged cross-sectional view taken along the line V-V in FIG. 2, and FIG. 6 is an enlarged view taken along the arrow ■ in FIG. 2. . l...Center differential, 2...Second part.
Four-layer switching mechanism, 3...Center differential lock/free switching mechanism, 5...Transfer, 6...Continuous drive system (rear wheel drive system), 7...Second Chamberlain faJ (!1.!
I drive system (front wheel drive system), 8... Differential (of the two-part driven side drive system), 9... Free wheel clutch, 10... Engine, 11... Transmission, 12
...output shaft, 13...differential case, 14...trunnion shaft, 15...pinion, 16...first side gear, 17...second side gear, 36...7xle, 41...freewheel actuator, 41
a...Lock operation side branch, 41b...Free operation side branch, 71...Two-part/four-layer remote changeover switch, 80
...Two-part/four-layer changeover detection switch.

Claims (1)

[Claims] (1) A center differential comprising a differential case to which the rotation of the output shaft of the transmission is transmitted, a pinion rotatably supported by the trunnion shaft of the differential case, and a pair of side gears that mesh with the pinion at the same time; Among the side gears, one of the front wheels or the rear wheels is a constant drive system connected to the first side gear, and among the side gears, the other of the front wheels or the rear wheels is connected to the second side gear. The second side gear is interposed between the driven side drive system during two-wheel drive and the second side gear connected thereto, and is operated by operating the two-wheel drive/four-wheel drive changeover switch. Two-wheel drive/four-wheel drive switching that allows switching between a two-wheel drive state in which the side gear and the driven side drive system are cut off during two-wheel drive, and a four-wheel drive state in which the second side gear and the driven side drive system are connected during two-wheel drive. and a center differential lock state that is linked to the operation of the two-wheel drive/four-wheel drive switching mechanism and prevents relative rotation between the differential case and the second side gear when in the two-wheel drive state, and the above-mentioned when in the four-wheel drive state. A center differential lock/free switching mechanism that switches between a center differential free state and a center differential free state that allows the differential case and the second side gear to rotate relative to each other, and a center differential lock/free switching mechanism that operates to switch between a center differential free state and a center differential free state that allows the differential case and the second side gear to rotate relative to each other; an axle that isolates between the differential and the axle shaft when in a two-wheel drive state by a double-acting actuator that is interposed in the 2WD/4WD switching mechanism and is operated using negative pressure as an energy source; A four-wheel drive vehicle, comprising: a freewheel clutch that switches between a free state and an axle lock state that connects the differential and the axle shaft when in a four-wheel drive state, wherein the two-wheel drive/four-wheel drive switching mechanism is A detection switch is further provided for detecting a switch to a four-wheel drive state, and an axle of an actuator that drives the freewheel clutch when the two-wheel drive/four-wheel drive changeover switch is switched from a two-wheel drive position to a four-wheel drive position. The actuating pneumatic circuit of the actuator is configured to apply negative pressure to the lock activation side compartment and communicate the axle free activation side compartment of the actuator to the atmosphere when the detection switch detects a four-wheel drive state. Characterized by
four wheel drive vehicle.