JPH01109123A - Torque split type four-wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To improve turning performance at the time of a medium speed and a medium steering by determining the torque distribution to front and rear wheels based on the relation between a vehicle speed and a steering angle and selecting one map out of two types of maps according to the friction coefficient of a road surface. CONSTITUTION:In the captioned vehicle in which the output of a transmission 2 is distributed to front and rear wheels by means of a center differential gear 3 while distributing part of a front-wheel torque to rear wheels via a hydraulic multiple disk clutch 6, a map for determining a torque distribution ratio based on the relation between a vehicle speed and a steering angle is provided on a control unit 100. Two types for a high friction road surface and for a low friction road surface are provided for the map and each map is selected according to the signal from a mu computing element mus. By determining a torque distribution ratio according to the selected map, the turning performance of the medium and large steering at the time of medium speed can be improved while getting rid of tight corner breaking and improving a straight advancement accelerating property and traction.

Description

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

The present invention relates to a torque split type 4M drive vehicle, and more particularly to a torque split type four wheel drive vehicle in which the torque distribution ratio between the front and rear wheels is such that the front wheel torque is large.

[Conventional technology]

Vehicles, more specifically, automobiles include front-wheel drive, rear-wheel drive, and even all-wheel drive. installed to drive the front wheels. This is a so-called front-wheel drive car, with the engine mounted in the front and driving the rear wheels. This is a so-called FR car, with the engine mounted in the rear and driving the rear wheels. This is a so-called FR car, with the engine mounted in the rear and driving the rear wheels. Although the number of so-called RR vehicles is small, midship type vehicles in which an engine is mounted between the wheelbases and drives the rear wheels are known. In particular, the number of vehicles is overwhelmingly the aforementioned FF cars, PR cars, etc., and most cars are included in either of these categories. FF cars have excellent driving stability and are difficult to spin, but they exhibit understeer characteristics when cornering, which makes them difficult to maneuver and difficult for the average driver.
There is a problem with so-called oral nature. Furthermore, although the latter has some drawbacks in terms of stability when running in a straight line, it has oversteer characteristics when cornering and is difficult to maneuver. Therefore, both FF cars and FR cars have their own strengths and weaknesses, and depending on the vehicle application and driving environment, both exhibit characteristics that are difficult to abandon. The car is known. This all-wheel drive vehicle is effective when driving on difficult roads and roads with low mWA, but when driving around town, there is a possibility of tight corner braking, making it a vehicle that does not have a tight turning radius. Therefore, in addition to transmitting torque from the engine output to the front and rear wheels via the center differential, a torque transmission system that does not go through the center differential is provided, and a torque distribution system is provided in this torque bypass transmission system, so that the torque is transmitted to the front and rear wheels. By increasing the amount of torque distribution, you can convert an all-wheel drive vehicle into a front-wheel drive vehicle or a PR vehicle.
Measures have been proposed to change the vehicle to one with driving characteristics similar to that of a car. Specifically, JP-A-62-2
No. 03826 can be mentioned.

[Problems to be solved by the invention]

In a vehicle equipped with a torque distribution device as described above, vehicle speed,
In other words, since the torque distribution is determined by the selected gear of the transmission, it is not possible to operate the vehicle as if it were an FF or FR vehicle depending on the driving environment and driving conditions. Therefore, this invention aims to improve the FF depending on the driving environment and driving conditions.
The purpose is to distribute torque so that the vehicle has the characteristics of a car or a PR car, and to improve turning performance when cornering and steering stability when driving in a straight line.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a map that determines the torque distribution ratio in relation to the vehicle speed and the steering angle, and this map can be used for two types of road surfaces: high friction road surfaces and low friction road surfaces. By selecting one of these, it is possible to improve the maneuverability of medium and large turns at medium speeds, eliminate tight corner braking, improve straight-line acceleration, and improve traction. It is characterized by the fact that

[For production]

Therefore, torque is distributed according to the weight distribution of the vehicle during steady driving, and torque is distributed to the rear wheels during accelerated steering on surfaces other than low-friction roads, improving controllability.

【Example】

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, FIG. 1 is an explanatory diagram of a torque transmission system of an all-wheel drive vehicle to which the present invention is applied. The output of an engine 1 is inputted to a center differential 3 by a planetary gear mechanism via a transmission 2. A propeller shaft 4 is provided from the sun gear 32 to the rear wheels, a large gear 33 coaxial with the large ring gear 32 is provided, and a propeller shaft 5 is provided from the sun gear 32 to the front wheels.
The input gear 51 (gear ratio 1:1) meshes with the input gear 51 (gear ratio 1:1). The output ratio at the center differential 3 is 60% to the propeller shaft 5 to the front and 40% to the propeller shaft 4 to the rear. This output distribution at the center differential, in other words, the torque distribution ratio of 60:40, is in accordance with the weight distribution of the vehicle, and the weight borne by the front wheels is 60:40. The weight burden on the rear wheels is 40. The propeller shaft 4 is provided with an input gear 41,
This input gear 41 meshes with an output gear 62 provided on an output shaft 61 of a hydraulic multi-disc clutch 6, which is a provision for a portion of the propeller shaft 5 extending rearward from the input gear 51 (gear ratio = input gear 51). output gear 61). The propeller shaft 4 transmits torque to the rear wheels 71 via the rear differential 7, and the propeller shaft 5 transmits torque to the front wheels 81 via the front differential 8. The front wheels 81 are appropriately steered by the steering handle 9. The angle is detected by a steering angle sensor 91. The engine 1 has a throttle 11,
The opening of the throttle 11 is determined by the opening sensor 11S and the engine 1.
The rotational speed is detected by a rotational speed sensor 1S, the opening degree of the accelerator 12 is detected by an accelerator opening degree sensor 12S, the operation of the brake 13 is detected by a brake sensor 13s, and the selected gear of the transmission 2 is detected by a gear position sensor 21.
Furthermore, the left and right of the front and rear wheels 71.81 have respective wheels 71.
Wheel speed sensor 71 installed at L, 71R, 81L, 81R
s, 81s, and the road surface condition is detected by μ sensor μS.
, the acceleration state is detected by the G sensor GS. Signals from each sensor are input to a control unit 100 having two maps, which will be described later, and are taken out as control signals for the hydraulic multi-disc clutch 6, and furthermore, a control signal for the throttle opening is also taken out. The control unit 10G is determined based on the relationship between the steering angle and the vehicle speed, and has a torque distribution map for high friction road surfaces (high μ) and low friction road surfaces (low μ), and receives signals from the μ calculator μS. A high μ map or a low μ map can be selected by switching the map changeover switch Msw. This high μ map and low μ map have the contents as shown in Figure 2, and determine torque distribution based on the relationship between vehicle speed (arithmetic average of four transport speed sensors) and steering angle. and high μ
During steady driving on a low-μ road surface, the torque is made to be initial distributed (for example, distributed according to weight). In other words, the engagement rate of the hydraulic multi-disc clutch 6 is "0".
By doing so, torque is transmitted to the front and rear wheels using a split distribution ratio using the center differential. In addition, during accelerated steering (near the exit of cornering), the rear wheels 711 and 71
Torque is distributed to RlpI, and the torque distribution is performed so that the vehicle that was running with FF sensitivity during the initial run becomes a PR-like vehicle, and the turning performance is improved. however,
On low μ road surfaces, control is performed using a low μ map to maintain steering stability. Basically, the turning performance is improved when running at medium speeds and with medium steering (Figure 3). Furthermore, when accelerating or going straight, torque is distributed according to the weight distribution of the vehicle, acceleration is estimated by G sensor G3, and when braking, control is performed according to ABS control conditions. In addition, when slipping starts, torque is distributed to the front wheels that are not slipping or to the rear wheels, and when all wheels start slipping, the throttle 11 is narrowed and the output of the engine 1 is reduced. It is supposed to be done.

【Effect of the invention】

As is clear from the above explanation, Torrus 1 of this invention
Ritsu type four-wheel drive vehicles are configured so that the torque distribution to the front and rear wheels is determined by the relationship between vehicle speed and steering angle, and one of two types of maps can be selected depending on the traction coefficient of the road surface. As a result, you can expect improved controllability during mid-speed and mid-steering maneuvers, elimination of tight corner braking, and improved traction when driving straight.

[Brief explanation of the drawing]

The accompanying drawings show an embodiment of the present invention; FIG. 1 is an explanatory diagram showing a torque transmission system of a four-wheel drive vehicle, FIG. 2 is an explanatory diagram of a map, and No. 3 UfA is a schematic diagram of the same map. 1... Engine, 1S... Rotation speed sensor, 11...
・Throttle, 11s... Throttle opening sensor, 1
2...Accelerator, 12s...Accelerator opening sensor,
13s...Brake sensor, 2...Transmission, 21...Gear position sensor 3...Center differential, 31...Sun gear 4...Propeller shaft, 41...Input gear 5...Propeller Shaft, 51... Input gear 6... Hydraulic multi-plate clutch, 61... Output shaft, 62... Output gear 7... Rear differential, 71... Rear wheel, 71s... Transport speed sensor 8...Front differential, 81...Front wheel, 81s
... Transport speed sensor 9... Steering handle, 9S... Rudder angle sensor μS... μ calculator, GS... G sensor, M
SW...map changeover switch patent applicant Fuji Heavy Industries Co., Ltd. agent Nobu Kobashi Patent attorney Susumu Murai Procedural amendment (voluntary) December 3, 1985 Commissioner of the Japan Patent Office / JX Jll Voice β Husband 1986 Patent Application No. 268878 2 Name of the invention Torque split type 4-wheel drive vehicle 3 Relationship with the person making the amendment Patent Applicant 1-7-2-4 Nishi-Shinjuku, Shinjuku-ku, Tokyo Agent 5, Subject of amendment (1) Full text of the specification 6, Contents of amendment (1) Amend the entire specification as shown in the attached sheet. (Supplementary f) Description 1, Name of the invention Torque split type four-wheel drive vehicle 2, Claims (1) The output of the center differential is distributed between the front wheels and the rear wheels by a torque splitter, and the torque of the front wheels is divided. A torque split type four-wheel drive vehicle configured to distribute torque to the rear wheels using a hydraulic multi-plate clutch is equipped with a map that determines the torque distribution ratio in relation to vehicle speed and steering angle, and this map Two types of road surfaces are available: low-friction and low-friction road surfaces, and by selecting one of them, you can improve the ability to turn large steering wheels at medium speeds, eliminate tight corner braking, and improve straight-line acceleration. A torque split type four-wheel drive vehicle characterized by being configured to improve traction. 3. Detailed description of the invention

[Industrial application field]

The present invention relates to a torque split type four-wheel drive vehicle, and more particularly to a torque split type four-wheel drive vehicle in which the torque distribution ratio between the front and rear wheels is such that the front wheel torque is large.

[Conventional technology]

Vehicles, more specifically, automobiles include front-wheel drive, rear-wheel drive, and all-wheel drive. installed to drive the front wheels. This is a so-called front-wheel drive car, with the engine mounted in the front and driving the rear wheels. This is a so-called front-wheel drive vehicle, with the engine mounted in the rear and driving the front wheels. This is a so-called FF car, with the engine mounted in the rear and driving the rear wheels. Although the number of so-called rtR vehicles is small, midship type vehicles in which an engine is mounted between the wheelbases and drives the rear wheels are known. In particular, in terms of the number of vehicles, the aforementioned PF cars, PR cars, etc. are overwhelmingly large, and most cars are included in either of these. FF cars have excellent driving stability and are less likely to spin, but they exhibit understeer characteristics when cornering, which makes the -M driver's maneuverability worse.
There is a problem with the so-called turning ability. Also, although the latter has some drawbacks in stability when running in a straight line, it has oversteer characteristics when cornering and is easy to maneuver. Therefore, both front-wheel drive cars and front-wheel drive cars have their own strengths and weaknesses, and depending on the vehicle application and driving environment, both exhibit characteristics that are difficult to abandon. The driving vehicle is known. This all-wheel drive vehicle is effective when driving on difficult roads and low-friction roads, but when driving around town, there is a possibility of tight corner braking, making it a vehicle that does not have a tight turning radius. Therefore, in addition to transmitting torque from the engine output to the front and rear wheels via the center differential, a torque transmission system that does not go through the center differential is provided, and a torque distribution mechanism is provided in this torque bypass transmission system, so that the torque can be transferred to either the front or rear wheels. It has been proposed to take measures such as changing an all-wheel drive vehicle to a front-wheel drive vehicle, or a vehicle with driving characteristics similar to a front-wheel drive vehicle, by increasing the amount of torque distribution. Specifically, JP-A-62-20
No. 3826 can be mentioned. [Problems to be Solved by the Invention] In a vehicle equipped with a torque distribution device as described above, the vehicle speed,
In other words, since the torque distribution is determined by the selected gear of the transmission, it is not possible to operate the vehicle as if it were an FF or FR vehicle depending on the driving environment and driving conditions. Therefore, this invention aims to improve the FF depending on the driving environment and driving conditions.
The purpose is to distribute torque so that the vehicle has the characteristics of a car or a PR car, and to improve turning performance when cornering and steering stability when driving in a straight line.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention is provided with a map that determines the torque distribution ratio in relation to the vehicle speed and the steering angle, and this map is divided into two types: a high friction road surface and a low friction road surface. is available, and by selecting this option, it is possible to improve turning performance during medium and large turns at medium speeds, eliminate tight corner braking, improve straight-line acceleration, and improve traction. It is characterized by having the following configuration.

[For production]

Therefore, torque is distributed according to the weight distribution of the vehicle during steady driving, and torque is distributed to the rear wheels during accelerated steering on surfaces other than low-friction roads, thereby improving turning performance.

【Example】

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, FIG. 1 is an explanatory diagram of a torque transmission system of an all-wheel drive vehicle to which the present invention is applied. The output of an engine 1 is inputted to a center differential 3 by a planetary gear mechanism via a transmission 2. A propeller shaft 4 is provided from the sun gear 31 to the rear wheels, a large gear 33 coaxial with the large ring gear 32 is provided, and a propeller shaft 5 is provided from the sun gear 31 to the front wheels.
The input gear 51 (gear ratio 1:1) meshes with the input gear 51 (gear ratio 1:1). The output ratio at the center differential 3 is 60% to the propeller shaft 5 to the front and 40% to the propeller shaft 4 to the rear. The output distribution at the center differential, in other words, the torque distribution ratio of 60:40, is in accordance with the weight distribution of the vehicle, with the weight borne by the front wheels being 6G and the weight borne by the rear wheels being 40G. The propeller shaft 4 is provided with an input gear 41,
This input gear 41 meshes with an output gear 62 provided on an output shaft 61 of a hydraulic multi-disc clutch 6, which is a provision for a portion of the propeller shaft 5 extending rearward from the input gear 51 (gear ratio = input gear 51). output gear 61). The propeller shaft 4 transmits torque to the rear wheels 71 via the rear differential 7, and the propeller shaft 5 transmits torque to the front wheels 81 via the front differential 8. The front wheels 81 are appropriately steered by the steering handle 9. The angle is detected by a steering angle sensor 91. The engine 1 has a throttle 11,
The opening of the throttle 11 is determined by the opening sensor 11S and the engine 1.
The rotational speed of the accelerator 12 is detected by the rotational speed sensor 1S, the opening of the accelerator 12 is detected by the accelerator opening sensor 12S, the operation of the brake 13 is detected by the brake sensor 13S, the selected gear of the transmission 2 is detected by the gear position sensor 21, and the front and rear wheels 71 are detected. .81 left and right wheels 71L,
Wheel speed sensor 71s installed on 71R, 81L, 81R,
81s, the road surface condition is detected by the μ sensor μS or μ switching s w , and the acceleration state is detected by the G sensor GS. Signals from each sensor are input to a control unit 100 having two maps, which will be described later, and are taken out as control signals for the hydraulic multi-disc clutch 6, and furthermore, a control signal for the throttle opening is also taken out. The control unit 100 is determined based on the relationship between the steering angle and the vehicle speed, has a torque distribution map for high friction road surfaces (high μ) and low friction road surfaces (low μ), and has torque distribution maps from the μ calculation unit μS. A high μ map or a low μ map can be selected by switching the map changeover switch Msw using the signal. This high μ map and low μ map have the contents as shown in Figure 2, and determine torque distribution based on the relationship between vehicle speed (arithmetic average of four wheel speed sensors) and steering angle. and high μ
During steady driving on both low-μ road surfaces, the torque is made to be initial distributed (for example, distributed according to weight). In other words, the engagement rate of the hydraulic multi-disc clutch 6 is "0".
By doing so, torque is transmitted to the front and rear wheels using a split distribution ratio using the center differential. Furthermore, during accelerated steering (near cornering), the rear wheels 71E are driven at different rates on both high-μ and low-μ road surfaces. Torque is distributed to the 71R side, and F-F during the initial run.
Torque distribution is performed so that what used to be a vehicle that used to drive with a feeling becomes an FR-like vehicle, and turning performance is improved. However, in order to maintain steering stability on low μ road surfaces, control is performed using a low μ map. 1! ! ! Basically, at medium speed, and
This improves the ease of speaking during mid-steering maneuvers (Figure 3). Furthermore, when accelerating or going straight, torque is distributed according to the weight distribution of the vehicle, acceleration is estimated by the G sensor GS, and when braking, control is performed according to ABS control conditions. In addition, when slipping starts, torque is distributed to the front wheels that are not slipping or to the rear wheels, and when all wheels start slipping, the throttle 11 is narrowed and the output of the engine 1 is reduced. It is supposed to be done.

【Effect of the invention】

As is clear from the above description, in the torque split type four-wheel drive vehicle of the present invention, the torque distribution to the front and rear wheels is determined by the relationship between the vehicle speed and the steering angle, and there are two types of torque distribution depending on the friction coefficient of the road surface. Since the structure is configured so that one of the maps can be selected, it is possible to improve the controllability at medium speeds and medium steering, eliminate tight corner braking, and further improve traction when driving straight. .

[Brief explanation of the drawing]

The accompanying drawings show an embodiment of the present invention; FIG. 1 is an explanatory diagram showing a torque transmission system of a four-wheel drive vehicle, FIG. 2 is an explanatory diagram of a map, and FIG. 3 is a schematic diagram of the same map. 1... Engine, 1S... Rotation speed sensor, 11...
・Throttle, 11S...throttle opening sensor,
12... Accelerator, 12s... Accelerator opening sensor, 13s... Brake sensor, 2... Transmission, 21... Gear position sensor 3... Center differential, 31... Sun gear 4...・Propeller shaft, 41... Input gear 5... Propeller shaft, 51... Input gear 6... Hydraulic multi-plate clutch, 61... Output shaft, 62... Output gear 7... Rear differential , 71...Rear wheel, 71s...Wheel speed sensor 8...Front differential, 81...Front wheel, 81s
... Transport speed sensor 9... Steering handle, 9S... Rudder angle sensor μS... μ calculator, GS... G sensor, M
sw...Map changeover switch Patent applicant: Fuji Heavy Industries Co., Ltd. Agent: Patent attorney: Makoto Kobashi Ukiyo Patent attorney: Susumu Murai

Claims (1)

[Claims] (1) In a torque split type four-wheel drive vehicle configured to distribute the output of the center differential between the front wheels and the rear wheels using a torque splitter, and also distribute a portion of the torque from the front wheels to the rear wheels using a hydraulic multi-disc clutch, Equipped with a map that determines the torque distribution ratio in relation to vehicle speed and steering angle, this map is available in two types: high-friction road surface and low-friction road surface, and by selecting one of them, it is possible to A torque split type four-wheel drive vehicle that is configured to improve steering performance, eliminate tight corner braking, improve straight-line acceleration, and improve traction.