JPH0537700Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a differential control device, and more particularly, to a device for controlling the differential of a differential device equipped with a differential limiting mechanism and installed in a vehicle. .

(Prior art) In addition to a normal differential mechanism, a differential device capable of limiting differential motion includes a differential limiting mechanism consisting of a plurality of friction plates and a hydraulic device for operating these friction plates. The differential that occurs is limited by bringing the friction plates into contact. This allows depending on the driving speed (e.g.
JP-A-61-102324, JP-A-61-102322), or depending on the magnitude of the ground load (JP-A-59
-199331 Publication) It is possible to limit the differential or release the limit to improve stability.

(Problem that the invention aims to solve) When a vehicle is traveling straight with the differential of the differential gear limited, and the tires receive random disturbances from the road surface, the vehicle will wobble and the stability when traveling straight will deteriorate. do. Therefore, stability can be further improved by detecting road surface disturbance and canceling the differential restriction depending on the magnitude of the disturbance. From this point of view, a differential control device was proposed (Japanese Patent Application No. 61-228446: Japanese Patent Application Laid-Open No. 1982-82834, Utility Application No. 180482: Japanese Utility Model Application No. 1983-86455, -189756: Utility Model Application Publication No. 63-94832).

The above proposal basically consists of a means for detecting a disturbance applied to the tires from the road surface, a means for detecting the magnitude of the steering angle, and a means for detecting the magnitude of the disturbance and the steering angle based on the signals from both of the means. a controller for determining whether to limit the differential or release the limit by determining the magnitude of the differential, and a means for operating the differential limiting mechanism controlled by a signal from the controller. .

However, in the differential control device according to the above proposal,
When driving on rough roads, the differential restriction may be lifted and sufficient traction cannot be secured.
There is a possibility that running performance cannot be improved.

An object of the present invention is to provide a differential control device that can improve running performance, especially when driving on rough roads.

(Means for Solving the Problems) The present invention is a device for controlling the differential of a differential gear having a differential limiting mechanism, which includes a means for detecting vehicle speed and a means for detecting disturbances applied to the tires from the road surface. means, a controller receiving signals from both means, and means for operating the differential limiting mechanism;
The controller determines whether the vehicle is traveling at a predetermined speed or higher based on the detected vehicle speed, and determines whether the vehicle is traveling on a rough road based on the detected disturbance, and determines whether the vehicle is traveling at a predetermined speed or higher based on the detected disturbance. and when the vehicle is traveling on a rough road, the operating means is controlled to release the differential restriction by the differential restriction mechanism.

(Functions and Effects) As a result of the controller's judgment that the vehicle is traveling at a predetermined speed or higher and is traveling on a rough road,
When the differential restriction is to be released, the controller controls the operating means to release the differential restriction. In other cases, that is, when the vehicle is running at a low speed lower than a predetermined speed, or when the vehicle is running at a speed higher than the predetermined speed but not on a rough road, the controller continues to limit the differential.

Only when traveling on rough roads at a predetermined speed or higher, the differential restriction is canceled to increase stability against yaw moment, and when traveling on rough roads at low speeds lower than the predetermined speed, traction is secured and the You can improve your sexuality.

Even if a disturbance is input, the differential restriction is not canceled each time, so the frequency of operation of the means for operating the differential limiting mechanism is reduced, and the durability of parts used in this operating means can be improved.

(Example) As shown in FIG. 1, the differential control device 10 controls the differential of a differential device 14 having a differential limiting mechanism 12, and includes means 16 for detecting vehicle speed.
, a means 18 for detecting a disturbance applied to the tire as vertical acceleration, a controller 20, and an operating means 22.

Any differential device can be used as long as it has a differential limiting mechanism. In the illustrated differential device 14, one of the shafts 30 is connected to a pair of side gears 28 (one of which is shown in the figure) that meshes with a plurality of pinions 26 disposed within the differential case 24. , the differential limiting mechanism 12 in relation to the differential case 24.
is provided.

The differential limiting mechanism 12 includes a plurality of first friction plates 34 that engage with each other via a spacer 32 of one shaft 30, and a plurality of second friction plates that engage with the differential case 24 via a transmission member 36. friction plate 38
Equipped with. The first friction plate 34 is the spacer 32
It is supported non-rotatably but movably in the axial direction of the shaft 30. On the other hand, a second friction plate 38 is supported by the enlarged diameter portion of the transmission member 36 so as to be non-rotatable and movable in the axial direction. The first friction plates 34 and the second friction plates 38 are arranged alternately.

A piston chamber 42 is provided in the differential carrier 40, and a first piston 44 is movably and non-rotatably disposed within the piston chamber 42. A second piston 46 is spaced apart from the first piston 44 , and the second piston 46
6 is supported by the spacer 32 so as to be non-rotatable and movable in the axial direction. Thrust bearing 4
8 is disposed between the first piston 44 and the second piston 46.

When hydraulic pressure is introduced into the piston chamber 42, the first piston 44 is pressed against the second piston 46 via the thrust bearing 48, and between the first friction plate 34 and the second friction plate 38, A friction force proportional to the pressing force is generated. This frictional force limits the differential movement of the differential device 14. The pressing force applied to the friction plates 34, 38 is applied to the thrust washers 50, 52.
and is transmitted to the differential carrier 40 via the thrust bearing 54 and received there.

The controller 20 is a CPU or a computer, receives signals from the vehicle speed detection means 16 and the disturbance detection means 18, determines the magnitude of the disturbance between the vehicle speed, and performs control as described below. In the illustrated embodiment, a signal from the steering angle detection means 60 is input to the controller 20.

In the illustrated embodiment, the operating means 22 includes a liquid pump 64, an unload relief valve 66, an accumulator 68, a current-controlled pressure reducing valve 70, and a check valve 72.

A pipe 74 is connected to the pump 64 and the differential carrier 40 of the differential limiting mechanism 12, and the pipe 74
4 communicates with the piston chamber 42. The unload relief valve 66 is installed in the pipe 74, and the current-controlled pressure reducing valve 70 is installed in the portion leading from the unload relief valve 66 to the differential limiting mechanism 12. Further, an accumulator 68 is connected between the unload relief valve 66 and the current-controlled pressure reducing valve 70, and a check valve 72 is installed between the unload relief valve 66 and the accumulator 68. The check valve 72 connects the unload relief valve 66 to the accumulator 6.
Allows only liquid flow or pressure transmission towards 8.

When pressurized liquid is supplied from the pump 64, the unload seat of the unload relief valve 66 is closed and the check valve 72 is opened. As a result, pump 64
The pressurized liquid from is led via pipe 74 to the accumulator 68, where the liquid pressure is increased. When the pressure of the accumulator 68 reaches the adjustment pressure of the unload relief valve 66, the unload relief valve 66 instantly opens, the pressurized liquid from the pump 64 flows back to the reservoir tank 76, and the check valve 72 closes. Thus,
A constant pressure is stored in the accumulator 68.

The current-controlled pressure reducing valve 70 has a DC solenoid installed in its pilot section, and controls the pressure continuously and steplessly by controlling the input current to the solenoid. The control pressure in this case is then substantially proportional to the input current. Therefore, if the current applied to the current-controlled pressure reducing valve 70 is controlled by the controller 20, an appropriate pressure can be obtained.

For example, the controller 20 executes a main routine as shown in FIG. 2, and a subroutine shown in FIG. 3 is inserted into this main routine at regular intervals.

In the main routine, initialization is performed 80 and steering angle δ is read 82. In advance of the controller 20, the relationship between the steering angle δ and the pressure P to be applied to the differential limiting mechanism 12, and the pressure P and the pressure P are determined by the current-controlled pressure reducing valve 7.
The relationship with the current I required to obtain 0 is stored as a map, and the pressure P is determined from the detected steering angle δ84. Next, a current I corresponding to the pressure P is determined 86 and this current I is outputted 88 to the differential limiting mechanism 12 . As a result, in the differential limiting mechanism 12, the friction plates 34 and 38 generate a friction force proportional to the pressure P.
The differential movement of the differential device 14 is limited.

During execution of the main routine, an interrupt routine shown in FIG. 3 is executed (100), and (101) the time T during which the differential restriction is released is set to T=0. Thereafter, the vehicle speed U is read 102, and the vehicle speed U is compared with a predetermined reference value _U0 (103).

When the vehicle speed U is equal to or higher than the reference value U ₀ , the disturbance α is read 104 and the detected disturbance α is compared with a predetermined reference value α ₀ 105 . Then, the disturbance α becomes the reference value α ₀
When this is the case, the time T is set to T=N (106), the differential restriction is set to be canceled (107), and the control signal is output (108).

If the above operation is repeated and the vehicle speed U becomes smaller than the reference value _U0 , the process immediately returns to the main routine (111). After returning to the main routine, the steering angle δ
The differential is limited based on 84,86.

Even if the vehicle speed U is greater than or equal to the reference value U ₀ , if the disturbance α is smaller than the reference value α ₀ , it is determined whether the time T is zero or not (109). If the time T is not zero, set the time T to T=T-1 at 110, set the differential limit to be canceled at 107, and output the control signal at 10.
8. Repeat the above operation. Thereafter, when the time T becomes zero (110), the process immediately returns to the main routine (111), and in the main routine, the differential is limited based on the steering angle δ.

In the embodiment, the main routine continuously controls the differential limiting amount depending on the magnitude of the steering angle δ, so that when the steering angle δ is small, the differential limiting amount is increased to improve straight-line stability. As the steering angle increases, the differential limiting amount can be reduced to improve turning performance. Furthermore, since the control is performed continuously, the vehicle characteristics do not suddenly change, unlike when differential restriction and release of a differential device is performed ON/OFF depending on the steering angle. In particular, it is possible to prevent unstable behavior due to switching between limiting and canceling the differential during rotation.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a differential control device, showing the differential device in cross section, FIG. 2 is a flowchart of a main routine, and FIG. 3 is a flowchart of an interrupt routine. 10...Differential control device, 12...Differential limiting mechanism, 14...Differential device, 16...Vehicle speed detection means,
18... Disturbance detection means, 20... Controller,
22... Operating means, 60... Rudder angle detection means, 70
...Current control pressure reducing valve.

Claims (1)

[Scope of utility model registration request] A device for controlling the differential of a differential gear having a differential limiting mechanism, the device comprising: means for detecting vehicle speed; means for detecting disturbances applied to the tires from the road surface; a controller receiving signals from both of the means; means for operating a differential limiting mechanism, the controller determines whether the vehicle is traveling at a predetermined speed or higher based on the detected vehicle speed, and determines whether the vehicle is traveling on a rough road based on the detected disturbance. A differential control device that controls the operating means to release differential restriction by the differential limiting mechanism when the vehicle is running at a speed higher than a predetermined speed and on a rough road.