JPS63110029A - Wheel drive controller for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To simplify a remote free wheel structure, by utilizing a power steering pump as a hydraulic source for engaging/disengaging a clutch which constitutes the remote free wheel mechanism. CONSTITUTION:In order to prevent back drive of a differential gear 7 by the torque from a right front wheel 6 during two-wheel drive, a remote free wheel mechanism 11 for blocking said power transmission path is provided to a right front axle shaft 9. In order to drive said remote free wheel mechanism 11, a hydraulic actuator 12 having a piston which is reciprocated by switching oil lead-in paths is provided. While a power steering pump 15 for feeding oil to a power steering circuit B is provided so as to feed oil to the hydraulic actuator 12 through the pump 15.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a four-wheel drive vehicle equipped with a switching function between four-wheel drive and two-wheel drive.
The present invention relates to a wheel drive control device for a wheel drive vehicle.

1' [Prior Art] It is well known that a four-wheel drive system is used to improve the running performance of an automobile on muddy, snowy roads, etc. However, when driving on a normal paved road, a two-wheel drive type is preferable from the standpoint of reducing mechanical loss in the power transmission section and improving fuel efficiency. Therefore, we installed a switching mechanism between two-wheel drive and four-wheel drive in the transfer device that transmits engine power to the wheels, and created a so-called part-time four-wheel drive system that allows switching between two and four wheels. is proposed. .

In such a part-time four-wheel drive system, mechanical loss is reduced during two-wheel drive compared to four-wheel drive, but mechanical loss is reduced between the idle wheels. Since the ring gear that makes up the differential device (hereinafter simply referred to as the differential) is backdriven by the rotation of the wheels, the oil in the differential is agitated and the propeller shaft is also driven. There was a problem.

Therefore, as a method to solve this problem, power transmission is cut off to the axle shaft on the side of the wheel that becomes the idle wheel during two-wheel drive. A so-called freewheel mechanism with a clutch interposed therein has been proposed.

Such freewheel mechanisms include a method in which a clutch is interposed on both the left and right axle shafts to prevent wheel power from being transmitted to the differential, or a clutch is interposed only on either the left or right axle shaft. A method is known (for example, see Japanese Patent Laid-Open No. 135320/1983). In particular, in the latter method, during two-wheel drive, the side gear on the side without the clutch is backdriven by the torque of the wheel, but the torque of the wheel is transmitted to the side gear on the side with the clutch. Therefore, the torque ratio of both side gears is approximately 1:0, and therefore, due to the differential operation of the differential, the former side gear backdrives the latter side gear, but the ring gear and propeller shaft are not backdriven. Mechanical losses are now significantly reduced.

By the way, connecting and disconnecting the clutch installed on the axle shaft as described above requires a force of 2 to 3 kg.
Conventionally, actuators consisting of negative pressure or electric motors have been used as this drive source, but their structures are complex and have many parts, and in order to obtain sufficient driving force, the actuators have to be used. There was a problem that it was large and bulky.

[Object of the invention] The present invention has been made in view of the above-mentioned conventional problems.
In a part-time 4-wheel drive vehicle that is equipped with a remote freewheel mechanism on the axle shear and foot of the wheel side, which becomes an idle wheel during wheel drive, the clutch that makes up the remote freewheel mechanism has a simpler structure and stronger drive. The purpose is to be able to drive with force.

[Structure of the Invention] In order to achieve the above object, the present invention provides a means for transmitting the power of the engine to the wheels with a switching mechanism between two-wheel drive and four-wheel drive, and also provides a mechanism for switching between two-wheel drive and four-wheel drive, and also provides a mechanism for switching between two-wheel drive and four-wheel drive. In a four-wheel drive vehicle in which a remote freewheel mechanism is provided on the side axle shaft, the remote freewheel mechanism is provided with a hydraulic actuator for intermittent driving thereof, and a power steering pump is used as a pressure source for the hydraulic actuator. A wheel drive control device for a four-wheel drive vehicle is provided, characterized in that a means for supplying oil is provided.

[Effects of the Invention] According to the present invention, a hydraulic actuator having a simpler structure than a negative pressure air type or an electric actuator is provided in order to connect/disconnect the clutch constituting the remote freewheel mechanism. Since the existing power steering pump with high discharge pressure is used as the power source, there is no need for a dedicated pump for the hydraulic actuator, making it possible to create a simple, powerful, and compact remote freewheel mechanism. Cost reduction can be achieved.

[Example] Examples of the present invention will be specifically described below.

As shown in Figure 1, the power transmission mechanism T of a part-time four-wheel drive vehicle consists of a two-wheel drive system with a built-in hub clutch located behind a transmission l that can extract engine output with torque depending on the driving condition. A transfer device 2 equipped with a wheel-to-four wheel switching mechanism transmits power to an input shaft (
A front propeller shaft 3 and a rear propeller shaft 4 are connected to the transfer device 2, and the front propeller shaft 3 is connected to the front wheels 5.6 by changing the rotational speed of the left and right wheels. Differential 7 and left and right front axle shafts 8.
The basic configuration is such that power is transmitted through the propeller shaft 9 and also transmitted from the rear propeller shaft 4 to the rear wheels by a similar mechanism (not shown).

In this embodiment, the front wheel 5.6 becomes an idler wheel when the two wheels are driven, and the right front axle shaft 9 is configured to transfer the torque of the right side moe transfer 6 to the differential 7 when the two wheels are driven. To prevent backdrive,
A remote freewheel mechanism 2 is provided to interrupt this power transmission path. To drive this remote freewheel mechanism 11, a hydraulic actuator 12 is equipped with a built-in piston 49 (see Fig. 2) that makes reciprocating motion by switching the oil introduction path. It is provided.

On the other hand, a power steering circuit 13 is provided to reduce the labor required for steering wheel operation, and an oil reservoir 55 is connected to this power steering circuit 13 via an oil passage 14.
A power steering pump 15 is provided to supply power steering oil stored in the engine (see FIG. 3).

In order to supply oil to the hydraulic actuator 12 using this power steering pump 15, the oil passage 14 has an oil introduction passage 1 in order from upstream.
6 and an oil return passage 17 are connected. An orifice 18 is interposed in the oil passage 14 at a position downstream from the connection position with the oil introduction passage 16 and upstream from the connection position with the oil return passage 17, and the resulting pressure drop causes the oil introduction passage 16 to The oil pressure on the side is higher than the oil pressure on the oil return passage 17 side. On the other hand, the hydraulic actuator 12 has a first oil passage 21 communicating with its left cylinder chamber 5 (see FIG. 2) and a second oil passage 22 communicating with its right cylinder chamber 52 (see FIG. 2). It is connected. The above oil introduction passage 16, oil return passage 17, first oil passage 2
1. The second oil passages 22 are each connected to an oil switching device 23 composed of a solenoid valve, and in response to an electric signal, connect the oil introduction passage 16 to the first oil passage 21 and connect the oil return passage 17 to the second oil passage. 22, or connect the oil introduction passage 16 with the second oil passage 22 and connect the oil return passage 17 with the first oil passage 21.

Hereinafter, the configurations of the differential 7, the remote freewheel mechanism 11, and the hydraulic actuator 12 will be explained in detail with reference to FIG.

As shown in FIG. 2, the differential 7 includes a drive pinion gear 32 attached to the tip of a drive shaft 31 to which power is transmitted from the front propeller shaft 3, a ring gear 33 that meshes with the drive pinion gear 32, and a ring gear 33 that meshes with the drive pinion gear 32. 33 and a differential case 34 formed integrally with the differential case 34.
A pinion shaft 35 has both ends fixed to the pinion shaft 35, a pinion gear 36.37 is rotatably fitted to the pinion shaft 35, and a pinion gear 36.37 is engaged with the pinion gear 36.37, and the left and right front axle shafts 8.
It consists of side gears 38, 39, etc. fixed to the left and right front wheels 5.6 (see Figure 1) based on the differential principle.
Each can rotate at different speeds. Note that the differential 7 is housed within a casing 41.

Further, the remote freewheel mechanism 11 is configured around a clutch 40, and the clutch 40 is attached to the other end of the drive-side front axle shaft 9a, to which the side gear 39 is attached to the end on the differential 7 side. Opposed to this wheel 42 is a driven wheel 42 attached to the other end of the driven front axle shaft 9b, to which the right front wheel 6 (see FIG. 1) is attached. A drive side wheel 43 and a sleeve 44 that can be engaged across splines formed on the outer peripheries of both wheels 42 and 43 are fitted into outer circumferential grooves of this sleeve 44 and are axially rotated. It consists of a fork 45 that slides, a shift rod 46 for driving this fork 45, and the like.

In the state shown in FIG. 2 in which the sleeve 44 is engaged only with the splines of the driven wheel 43, the clutch 40 is in a disconnected state, and on the other hand, the sleeve 44 is on the left side from the state shown in FIG. direction (differential 7 direction),
The clutch 40 is connected when it is engaged across the splines of both the drive side and slave drive side wheels 42,43.

In order to reciprocate the shift rod 46 of the remote freewheel mechanism 11 in the axial direction of the front axle shaft 9, the shift rod 46 is connected to the connecting rod 47.
The connecting rod 47 is connected to the hydraulic actuator 12
The piston 49 is fitted into a cylinder 48 and is connected to a piston 49 fitted into the cylinder 48 so as to be able to reciprocate and slide. As shown in FIG. 3, this piston 49 allows high pressure oil upstream of the orifice 18 to flow from the oil introduction passage 16 through the oil changer 23 and the first oil passage 21 into the left cylinder chamber 51 in the cylinder 48. When introduced, the oil is moved to the right, while similarly high-pressure oil is transferred from the oil introduction passage 16 to the oil switching device 23.
When the oil is introduced into the right cylinder chamber 52 through the second oil passage 22, it is moved to the left (see FIG. 1). Note that when high-pressure oil is introduced into the left cylinder chamber 51 via the first oil passage 21, the piston 49 is moved rightward, so that the oil held in the right cylinder chamber 52 is in turn Second oil passage 22, oil switching device 23. The pressure downstream of the orifice 14 is returned to the oil passage 14 through the oil return passage 17, where the pressure has decreased slightly (
(see figure).

In addition, the right cylinder chamber 52 is
Similarly, when high-pressure oil is introduced into the left cylinder chamber 51, the oil in the left cylinder chamber 51 is sequentially introduced into the first oil passage 21.
The oil is returned to the oil passage 14 via the oil switching device 23 and the oil return passage 17 (see Fig. 1).
.

Next, the operation of the hydraulic actuator 12 will be explained with reference to FIG.

The oil stored in the oil reservoir 55 is constantly circulated between the power steering circuit 13 and the power steering circuit 13 via the oil passage 14 by the power steering pump 15. In the above power steering circuit 13, a 20-meter drive is used to change the direction of the front wheels 5.6 (see Fig.
Since an output of ~50 kg is required, the power steering pump 15, which is the source of this output, has a structure that can ensure a strong output, and is designed to supply oil, which is the output medium, with sufficient discharge pressure and flow rate. aisle! I am sending it to 4th. When the oil discharged from the power steering pump passes through the orifice 18, a pressure drop occurs, so the oil introduction passage 16 connected upstream of the orifice 18 is connected to the orifice return connected downstream of the orifice 18. The pressure is always higher than that in the passage 17, and this pressure difference serves as a power source for the hydraulic actuator 12.

During two-wheel drive, the oil switching device 23 composed of a solenoid valve operates to connect the oil introduction passage 16 to the first oil passage 21 and to connect the oil return passage 17 to the second oil passage 22. . As a result, high pressure oil is introduced into the left cylinder chamber 51 of the hydraulic actuator 12, and the pressure in the left cylinder chamber 51 becomes higher than the pressure in the right cylinder chamber 52, and the piston 4
9 is moved to the right. As a result, the shift rod 46 is moved to the right via the connecting rod 47, the fork 45 attached to the shift rod 46 slides the sleeve 44 to the right, and the sleeve 44 engages only with the slave drive wheel 43. Therefore, it is mechanically isolated from the driving side wheel 42 and the secondary driving side wheel 431 (backdrive is eliminated). At this time, the force required to slide the sleeve 44, that is, the required output of the hydraulic actuator 12, is 2 to 3 kg, and the pressure difference between the oil introduction passage I6 and the oil return passage 17 is adjusted to correspond to this. , the diameter of the orifice 18 is set. On the other hand, the oil held in the right cylinder chamber 52 is pushed out to the second oil passage 22 by the piston 49 and passes through the oil return passage 17 to the oil passage 1.
Returned to 4.

On the other hand, during four-wheel drive, the oil switching device 23 operates to connect the oil introduction passage 16 to the second oil passage 22 and to connect the oil return passage 17 to the first oil passage 21 . As a result, high pressure oil is introduced into the right cylinder chamber 52 of the hydraulic actuator 12, and the pressure in the right cylinder chamber 52 is reduced to the left cylinder chamber 52.
1 and the piston 49 is moved to the left. As a result, the shift rod 46 is moved leftward via the connecting rod 47, the fork 45 slides the sleeve 44 leftward, and the sleeve 44 is engaged with both the driving wheel 42 and the slave driving wheel 43. Thus, both wheels 42, 43 are connected and rotate as one. Thereby, the power of the engine is transmitted to the right front wheel 6.

As mentioned above, the output of the hydraulic actuator 12 is 2 to 3 kg, while the power steering circuit 13
Since the output of the hydraulic actuator 12 is 30 to 50 kg, the power spent on the hydraulic actuator 12 does not substantially affect the output of the power steering circuit 13.

As described above, according to the present invention, by using the existing power steering pump I5 as a hydraulic power source, the remote freewheel mechanism of a part-time four-wheel drive vehicle can be made simple, powerful, and compact.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a power transmission mechanism for a part-time four-wheel drive vehicle showing an embodiment of the present invention. FIG. 2 is a plan sectional view of essential parts of the power transmission mechanism including a differential and a remote freewheel mechanism. FIG. 3 is an operation circuit diagram for explaining the operation of the hydraulic actuator. l...Transmission, 2...Transfer device, 3, 4...Propeller shaft, 7...Differential resolution, shaft device (differential) 1.8.9...Front axle shaft, 11...Remote Freewheel mechanism, 12... Hydraulic actuator, 15... Power steering pump, 40... Clutch. Patent developer Mazda Motor Corporation

Claims (1)

[Claims] (1) A switching mechanism between two-wheel drive and four-wheel drive is provided as a means of transmitting engine power to the wheels, and a remote freewheel mechanism is provided on the axle shaft on the wheel side that becomes an idle wheel when driving two wheels. 4. A wheel drive vehicle, characterized in that the remote freewheel mechanism is provided with a hydraulic actuator for intermittently driving the remote freewheel mechanism, and a means for supplying oil to the hydraulic actuator using a power steering pump as a hydraulic source. Wheel drive control device for wheel drive vehicles.