JPS62221924A - Car speed detecting method for four-wheel drive type vehicle - Google Patents

Abstract

PURPOSE:To detect the car speed accurately even if a slip takes place during the period of car running by detecting revolving speed of a front wheel driving member and a rear wheel driving member by each of separate revolving speed sensors respectively whereby setting up the smaller one as the car speed out of the detected revolving speed. CONSTITUTION:Each of a rear wheel revolving speed sensor 122 and a front wheel revolving sensor 124 includes an electromagnetic pick up so as to detect each revolving speed of a rear wheel and a front wheel drive output member. Then the comparison of the detected value is made between the rear wheel revolving sensor 122 and the front wheel revolving sensor 124, and the rear wheel revolving speed is, for example, found to be smaller than the front wheel revolving speed, the front wheel is judged to be being slipped whereby the rear wheel revolving speed is set up as the car speed. owing to this constitution, even if the front wheel slips, the car speed can be accurately detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vehicle speed detection method for a four-wheel drive vehicle, and particularly to a four-wheel drive vehicle having an automatic transmission for the vehicle. The present invention relates to a method for detecting a vehicle speed required for speed change control.

BACKGROUND OF THE INVENTION A four-wheel drive vehicle having an automatic transmission for a vehicle is already known, and is disclosed, for example, in Japanese Patent Application Laid-Open No. 56-138020. Automatic transmissions for vehicles generally automatically switch gears according to a predetermined shift pattern depending on medium speed and engine load such as throttle opening.

Detection of vehicle speed for this shift control has conventionally been carried out using only the rotational speed of either the rear wheel drive output member or the front wheel drive output member, even in four-wheel drive vehicles. The vehicle speed is determined.

Problem to be Solved by the Invention When the vehicle is running, if the wheel on the rotation speed detection side for detecting the vehicle speed does not slip on the road surface, the vehicle speed can be accurately detected from the rotation speed of this wheel. However, if these wheels slip on the road surface, the vehicle speed cannot be detected accurately, and when this vehicle speed is used for speed change control of a vehicle automatic transmission, the vehicle speed is determined by the degree of slippage of the wheels. A phenomenon occurs in which the gear position changes moment by moment.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle speed detection method for a four-wheel drive vehicle that can accurately detect vehicle speed even if either the front wheels or the rear wheels slip on the road surface.

Means for Solving the Problems According to the present invention, the rotational speed of the output member for front wheel drive and the rotational speed of the output member for rear wheel drive are individually determined by separate rotational speed sensors. This is achieved by a method for detecting a medium speed of a four-wheel drive vehicle, which is characterized in that the vehicle speed is determined by detecting the rotation speed of the two rotation speed sensors and determining the smaller of the rotation speeds detected by the two rotation speed sensors as the vehicle speed.

Functions and Effects of Lighting In the vehicle speed detection method for a four-wheel drive vehicle according to the present invention,
The rotational speed of each of the output member for bamboo wheel drive and the output member for rear wheel drive is detected, and the smaller rotational speed is used as the vehicle speed, so either the front or rear wheels are relative to the road surface. When slippage occurs, vehicle speed b is accurately detected, and based on this vehicle speed, shift control of the automatic vehicle transmission can be performed accurately even when slippage occurs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 is a skeleton diagram showing a four-wheel drive power transmission device used to implement the vehicle speed detection method according to the present invention. In the figure, reference numeral 10 indicates an internal combustion engine (J3). Device 3
0 are connected in order.

The automatic transmission 20 for a vehicle includes a hydraulic torque converter 22 of a general structure provided in a converter case 21 and a gear type transmission @26 provided in a transmission case 24. The input member 22 is drivingly connected to the output shaft (crankshaft) 12 (not shown) of the internal combustion engine 1, and the rotational power of the internal combustion engine 1 is transferred to the transmission 2 via the hydraulic torque converter 22.
It is designed to be given to 6. The transmission 26 is a well-known transmission constructed of a planetary gear mechanism or the like, and is configured to switch between a plurality of gear stages, and is controlled by the hydraulic control device 100.

As clearly shown in FIG. 2, the four-wheel drive transfer device 30 has a TI star gear type center differential device 32 for full-time 4WD. Range cell equipped FE! Reference numeral 32 denotes a carrier 34 as an input member to which rotational power is applied from the output shaft 27 of the transmission 26, a planetary pinion 38 rotatably supported by the carrier by the shaft 36, and a number gear 40 meshed with the planetary pinion 38. and a ring gear 42, the ring gear 42 is connected to a rear wheel drive shaft 44,
The sun gear 40 is connected to the output shaft 27 and a front wheel drive intermediate shaft 46 in the form of a wide open sleeve.

The four-wheel drive transfer 1 device 30 is provided with a front wheel drive intermediate shaft 46 and a front wheel drive shaft 48 in the 1L row. The driving connection is made by an endless chain 54 that meshes with 50 and 52.

A hydraulically actuated differential control clutch 60 that selectively connects the ring gear 40 and the ring gear 42 is provided in the four-wheel drive 1 to lance force device 30. This is performed by the hydraulic control device 110 provided in the transfer device 30.

The differential control clutch 60 is a hydraulic servo type wet multi-disc clutch, and includes a clutch drum 62 fixedly connected to the sun gear 4o, a clutch sleeve 64 fixedly connected to the ring gear 42, and a clutch drum 62 fixedly connected to the ring gear 42, and a clutch drum 62 fixedly connected to the ring gear 42. It has a clutch disc 66 provided, a clutch plate 68 provided on the outer periphery of the clutch sleeve 64, and a double cylinder type hydraulic servo device 70.
The servo pistons 76 and 78 are moved to the right in the figure against the spring force of the return spring 80 by the servo oil pressure supplied to the oil chambers 72 and 74 of 0, and the sun gear of the center differential device 32 is connected to the sun gear of the center differential device 32 in a torque transmission relationship. 40 and ring gear 42 are connected, and the transmission torque capacity is increased proportionally in accordance with an increase in servo oil pressure supplied to oil chambers 72 and 74.

One end of a rear propeller shaft 58 is drivingly connected to the rear wheel drive shaft 44 through a universal joint 56 .

One end of a front propeller shaft 84 is connected to the front wheel drive shaft 48 via a universal joint 82 . The front propeller shaft 84 extends approximately parallel to the axis of the vehicle automatic transmission 20 on one side thereof, and is connected to the front differential system fi by a universal joint 86 and an intermediate connecting shaft 88 at the other end.
! It is connected to one end of a drive pinion shaft 92, which is the input shaft of the f90. The drive pinion shaft 92 has an internal combustion engine of 1 ton.
It is rotatably supported by a differential case 94 that is integrally molded with an oil pan 14 made of cast iron.

A drive pinion 96 made of a bevel gear is provided at the end of the drive pinion shaft 92, and the drive pinion meshes with a ring gear 98 of the front differential device 90.

The hydraulic control devices 100 and 110 are electrical control devices 12
It is operated based on a control signal from 0 to perform gear change control of the transmission 26 and transmission torque control of the differential Ill 1111 clutch 60.

The control device 120 includes a microcomputer with a general structure, and receives information regarding the rear wheel rotation speed from a rear wheel rotation speed sensor 122, information regarding the front wheel rotation speed from a front wheel rotation speed sensor 124, and information regarding the front wheel rotation speed from a throttle opening sensor 126. Information about the throttle opening of the internal combustion engine 1, information about the manual shift range from the manual shift position sensor 128, and information about the input torque given to the four-wheel drive transfer device 30 from the input torque sensor 130 are respectively given. In particular, the control signal for controlling the shift speed of the transmission 7 according to a predetermined shift pattern according to the vehicle speed and throttle opening determined by the manual shift range and the rear wheel rotation speed or the front wheel rotation speed. The hydraulic control device 110 outputs a control signal to the hydraulic control device 100 and also outputs a control signal to υJilt the transmission one herk capacity of the differential control clutch 60 according to the input torque.
It is designed to output to.

The rear wheel rotation speed sensor 122 is composed of an electromagnetic pickup 122a attached to the housing 31 of the four-wheel drive transfer device 30 and a gear-shaped uneven portion 122b formed on the outer peripheral surface of the ring gear 42. The rotation speed of a ring gear 42, which is an output member, is detected.

The front wheel rotation speed sensor 124 is a four-wheel drive transfer
The electromagnetic pickup 124a attached to the housing 31 of the housing 30 and the clutch drum 6 of the operation control clutch 60
An annular member 124 attached to the outer peripheral surface of 2
b, and detects the rotational speed of a clutch drum 62 integrated with the sun gear 40, which is an output member for driving the front wheels.

'Fi magnetic pickup 122 of rear wheel rotation speed sensor 122
a and the electromagnetic pickup 24a of the front wheel rotation speed sensor 124
and are arranged adjacent to each other in the housing 31 of the four-wheel drive transfer system a30 for ease of maintenance and common wiring harness. Rear wheel rotation speed sensor 122
The gear-shaped uneven portion 122b of the front wheel rotation speed sensor 124 and the annular comb tooth member 124b of the front wheel rotation speed sensor 124 are configured to have the same diameter.
1 go will be the same. As a result, the electromagnetic pickup 122
The vehicle speed due to the rear wheels and the vehicle speed due to the front wheels are determined by direct comparison between the pulse signal that a outputs in response to the rotation of the gear-shaped uneven portion 122b and the pulse signal output by the MFII pickup 124a in response to the rotation of the annular comb tooth member 124b. A determination is made as to which of the following is smaller.

FIG. 3 shows the automatic change y! of the automatic transmission 20 for a vehicle at the V4 position 26. It shows the A point. In this shift control, in order to more accurately detect the actual vehicle speed even if either the front wheels or the rear wheels are slipping on the road surface, first the rear wheels detected by the rear wheel rotation speed sensor 122 are The front wheel rotation speed Nr is detected by the front wheel rotation speed sensor 124.
It is determined whether or not it is smaller than f, and if Nr<Nf, it is assumed that the front wheels are slipping and the rear wheel rotation speed sensor 1
The rear wheel rotational speed Nr detected by the front wheel rotational speed sensor 122 is taken as the vehicle speed V, whereas when Nr<Nf, the rear wheel is slipping, and the front wheel rotational speed N'' detected by the front wheel rotational speed sensor 124 is taken as the vehicle speed V. This is done and this vehicle speed ■
and the throttle opening e detected by the throttle opening sensor 126 and the manual shift position sensor 126
A gear position is determined in response to a signal related to a manual shift position, and the gear position is changed based on the determined gear position.

In the above, the present invention has been described in detail with respect to specific embodiments, but the present invention is not limited thereto.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the invention.

[Brief explanation of drawings]

FIG. 1 is a skeleton diagram showing an example of a four-wheel drive power transmission device used to implement the vehicle speed detection method according to the present invention, and FIG. 2 is a vehicle speed detection diagram used to implement the vehicle speed detection method according to the present invention. FIG. 3, which is a longitudinal cross-sectional view showing the device portion, is a flowchart showing how to control the speed change of the automatic transmission for a vehicle based on the vehicle speed detected by the vehicle speed detection method according to the present invention. DESCRIPTION OF SYMBOLS 10... Internal combustion engine, 12... Output shaft, 20... Vehicle automatic transmission, 21... Converter case, 22...
...Fluid torque converter, 24...Transmission case, 26...Transmission device, 27...Output shaft, 28...Input member, 30...Transfer device for four-wheel drive. 31... Housing, 32... Center differential device, 34... Carrier, 36... Shaft, 38
... Plalet Ribinion, 40... Sangia, 42
...Ring gear, 44...Rear wheel drive shaft, 46...
Front wheel drive intermediate shaft, 48...Front wheel drive shaft, 50152
...Sprocket, 54...Chain, 56...
Universal joint, 58... Rear propeller shaft, 60... Differential control clutch, 62... Clutch drum, 64...
Clutch sleeve, 66...Clutch disc, 68
...Clutch plate. 70...Hydraulic servo device, 72.74...Oil chamber, 7
6.78... Servo piston, 80... Return spring,
82...Universal joint, 84...Front propeller shaft 8
6...Universal joint, 88...Intermediate connection shaft, 90...
Front differential device, 92... Drive pinion shaft. 94... Differential case, 96... Drive pinion, 98... Ring gear, 100.101
... Hydraulic control device, 120 ... Control device, 122.
...Rear wheel rotation speed sensor, 122a...Electromagnetic pickup. 122b...Gear-shaped uneven portion, 124...Front wheel rotation speed sensor, 124a...Electromagnetic pickup, 124b
... Annular 11-tooth member, 126... Throttle opening sensor. 128...Manual shift position sensor, 13
0...Input torque sensor

Claims (1)

[Claims] The rotational speed of the output member for front wheel drive and the rotational speed of the output member for rear wheel drive are individually detected by separate rotational speed sensors,
A vehicle speed detection method for a four-wheel drive vehicle, characterized in that the smaller of the rotational speeds detected by these two rotational speed sensors is taken as the vehicle speed.