JPH01164844A - Down shift control device for vehicle incorporating automatic transmission - Google Patents

Abstract

PURPOSE:To aim at enhancing the power characteristic of a vehicle on a slope and at ensuring the safety on a turning road by changing over a counter speed change gear section so as to compensate differences in gear ratio between speed stages in a main speed change gear section when control is made depending upon an inclined angle and a steering angle. CONSTITUTION:An automatic transmission is disposed therein with a main speed change gear section having large differences in gear ratio between speed stages, and a counter speed change gear section in series with the main speed change gear section on a power transmission path, having small differences in gear ratio between speed stages. During normal running, the gear shift control is made for only the main speed change gear section in accordance with a speed change map containing vehicle speeds and engine loads. Further, depending upon an inclination angle of a running road and a steering angle, a down-shift means compulsorily carries out the down-shift of the transmission more strongly as the inclination angle or the steering angle is larger, including the speed change of the counter speed change gear section. Thereby it is possible to finely reconcile enhancing the power characteristic of the vehicle on a slope and ensuring the safety during a turning road.

Description

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

The present invention relates to a downshift mill control device for a vehicle equipped with an automatic transmission, and more particularly to an improvement of a downshift control device for a vehicle equipped with an automatic transmission, taking into consideration the inclination angle of a running road and the steering angle.

[Conventional technology]

A gear transmission mechanism and a plurality of frictional engagement devices are provided, and the engagement of the frictional engagement devices is selectively switched by operating a hydraulic control device to execute a gearshift according to a predetermined shift map. Automatic transmissions for vehicles are already widely known. The shift map is normally determined based on the vehicle speed and engine load, and a specific gear stage is determined by detecting the vehicle speed and engine load. Shift control of automatic transmissions is, in principle, performed based on this shift map, but conventionally, the slope angle of the road (slope) is also detected, and when the slope angle is greater than a predetermined value, the highest gear (
A technology has been disclosed that prohibits running in the overdrive stage (for example, Japanese Patent Publication No. 15301/1986).
. According to this technology, if the current gear position is other than the overdrive position, shifting to the overdrive position is prohibited, and the current gear position is the overdrive position]1.
At Y, the control dependent on the shift map is temporarily canceled and a forced downshift is performed. Therefore, the power performance can be improved accordingly. On the other hand, if the shift control of the automatic transmission is executed based on the shift map, this shift control will basically be performed even when the vehicle is turning. However, when a gear shift is performed during the turning, torque fluctuations or speed fluctuations occur, which not only gives the C driver an unexpected sense of fear, but also particularly when a downshift is performed at a sharp curve, etc. There is a risk that the sudden increase in driving force may cause problems such as side slipping of the vehicle. Conventionally, as a technique for solving such problems,
There is a technique disclosed in Japanese Patent No. 9729. In other words, this technology stops shifting when the vehicle is turning,
This is to prevent and cover unexpected torque fluctuations by the driver.

[Problems to be solved by the invention]

However, according to the prior art related to the above-mentioned Japanese Patent Publication No. 61-15301, when the slope angle of the traveling road is detected to be greater than a predetermined value, traveling in the highest speed gear is only prohibited. The problem was that it was not possible to increase power. For this problem, not only the highest gear, but also when the automatic transmission is in the second gear, third gear, etc.
It is also conceivable to configure the system to actively downshift to first gear, second gear, and so on. However, in this case, the downshift is generally too strong, giving rise to the problem of unexpected shift shock to the driver. To solve this problem, it would be possible to increase the number of gears and reduce the difference in gear ratio between each gear in the automatic transmission, but increasing the number of gears would make the structure extremely complex, which would increase costs. is remarkable. Furthermore, when trying to combine control based on slope angle with control that suppresses downshifts on turning roads as described above, roads with steep slope angles, such as mountain roads, must be combined with control based on turning roads at the same time. Therefore, both controls can easily cancel each other out, effectively making the downshift control that detects the tilt angle and steering angle no longer function, or the execution of one of them can cause the usage to be completely ignored. The problem was that I had something to do.

[Purpose of the invention]

The present invention has been made in view of such conventional problems, and the basic structure of an automatic transmission has been modified. ! It is an object of the present invention to provide a downshift control device for a vehicle equipped with an automatic transmission that can perform extremely fine downshift control according to the inclination angle of the road and the steering angle without making things too complicated.=4 -

[Means to solve the problem]

As summarized in FIG. 1, the present invention includes a main transmission section with a large difference in gear ratio between gears, and a main transmission section that is arranged in series with the main transmission section on a power transmission system, an automatic transmission comprising an auxiliary transmission section in which a difference in gear ratio is set to be smaller than a difference in gear ratio of the main transmission section; means for detecting vehicle speed; means for detecting engine load; and means for changing the speed of the main transmission section of the automatic transmission depending on the engine load, means for detecting and detecting the inclination angle of the traveling road, means for detecting the steering angle, and the inclination angle and the steering angle. When the tilt angle is large, the downshift of the automatic transmission is executed more strongly, including the shift of the sub-transmission part, and when the steering angle is large, the downshift of the automatic transmission is executed more strongly. The above object has been achieved by providing a suppressing means. (Operations and Effects of the Invention) In the present invention, an automatic transmission is arranged in series on a power transmission system with a main transmission section having a large difference in gear ratio between each gear stage, and and an auxiliary transmission section in which the difference in gear ratio between the gears is set to be smaller than the difference in gear ratio of the main transmission section.During normal driving, the gear shift section is configured based on the vehicle speed and engine load. According to the map, only the main transmission section is controlled to change gears.Depending on the inclination angle of the road and the steering angle, the automatic transmission is controlled more strongly when the inclination angle is large, including the shift of the auxiliary transmission section. The automatic transmission according to the present invention has a main transmission section and an auxiliary transmission section. Normal speed change control is performed only by the main transmission section.Therefore, for this main transmission section, for example, the same speed change mechanism as the conventional one can be used.Looking at the automatic transmission as a whole, However, when performing control dependent on the tilt angle and steering angle, the difference in gear ratio between each gear of the main transmission section must be adjusted. Since it is possible to switch the sub-transmission section to fill the gap, it becomes possible to perform extremely detailed downshift control.For example,
The main transmission section has four gear stages, and the sub-transmission section has two high and low gears.
When the vehicle has eight gears, it is possible to perform fine downshift control between substantially eight gears. As a result, according to the present invention, it is possible to finely balance improving power performance on slopes and ensuring safety on turning roads without any trouble for the driver. Note that in the present invention, there are limitations on how to specifically combine execution of the downshift of the automatic transmission based on the tilt angle α and suppression of the downshift of the automatic transmission based on the steering angle β. It's not something you do. For example, as in the embodiments described later, the configuration may be such that the automatic transmission downshifts are executed once based on the tilt angle α, and the extent of this execution is changed depending on the steering angle β. . or,
On the contrary, it is based on "suppression" of the downshift of the automatic transmission based on the steering angle β (downshift that should basically occur in the main transmission based on the shift map),
It is also possible to configure the degree of suppression to be changed depending on the inclination angle α. Naturally, it is also possible to compromise both of these concepts. In a specific embodiment, which type should be selected may be determined after considering the characteristics that the vehicle should have.

【Example】

Embodiments of the present invention will be described in detail below based on the drawings. FIG. 2 schematically shows a vehicle automatic transmission to which the present invention is applied. This automatic transmission includes a main transmission section 2 that can configure four gears, and a sub-transmission section 4 that can switch between direct coupling (1-1) and deceleration (L). The main transmission section 2 includes two planetary gear systems M21.22, and the planetary gear systems 21.22 are connected to clutches C1 to C4,
This is a well-known system that is controlled by brakes B1 and B2, one-way brakes F1 and F2, and achieves four forward speeds and one reverse speed. On the other hand, the sub-transmission section 4 is arranged in series with the main transmission section 2 on the power transmission system. This auxiliary transmission unit 4 is a well-known device that includes one planetary gear device 41, controls this planetary gear device by a clutch C5, a brake B3, and a one-way clutch F3, and switches between direct coupling and deceleration. FIG. 3(A) shows the state of engagement/disengagement control of the clutches, brakes, and one-way clutches at each gear stage in the main transmission section 2.
The state of engagement/disengagement control of the brake and one-way clutch is shown in FIG. 3(B). Here, the ◎ mark indicates that the engine brake is engaged only when necessary, and the O mark for a one-way clutch indicates that the engine brake is engaged only when necessary.
Each indicates that it operates (engages and transmits power) only when driving. The main transmission section 4 is controlled to change gears in the same manner as in the prior art. That is, the computer 6 includes a throttle sensor 61 that detects the throttle opening, a vehicle speed sensor 62 that detects the vehicle speed -1n (rotational speed of the output shaft 51 of the automatic transmission), and sensors for drive, reverse, parking, etc. Output signals from shift position sensors 63, etc. for detecting shift 1 to positions are input, and these (
Based on the fi number information, shifts from the first gear to the fourth gear are executed via the main transmission section hydraulic control means 8 according to a predetermined shift map. The computer 6 also receives signals from an inclination angle sensor 67 that detects the inclination angle α of the road and a steering angle sensor 68 that detects the steering angle β. Shift control of both the sub-transmission section 2 and the sub-transmission section 4 is carried out via the main and sub-transmission section hydraulic control means 8.10. In this embodiment device, the sub-transmission section 4 is normally maintained at the high speed side (H), and can be switched to the low speed side (L) as appropriate depending on the inclination angle α and the steering angle β. ing. FIG. 4 shows the control flow in this embodiment device. First, in step 102, the throttle opening, vehicle speed, shift position, etc. are detected, and in step 104
In this step, the basic gear stage of the main transmission section 2 is determined based on the shift map in exactly the same manner as in the conventional method. Thereafter, the process proceeds to step 106, where the tilt angle α and steering angle β are detected. In step 108, a threshold value a111 related to the inclination angle α is
, C (Q < a < b < C). That is, in this control flow, the inclination angle α is set to the threshold values a and b.
, c into four regions: strong, medium, weak, and fine. If the inclination angle α is extremely small or flat, step 10 is performed.
The basic gear determined in step 4 is used as is (step 112>, and as the inclination angle a increases, only the sub-transmission section 4 is shifted to the lower speed side (step 114); only the main transmission section 2 is shifted to one gear). Set to low speed (step 118)
Step 120): Downshift the main transmission section 2 by one gear to the low speed side and set the auxiliary transmission section 4 to the low speed side.
In this way, the basic gear determined in step 104 is corrected. In step 108, threshold values a, b, and c for determining this area are determined according to the detected steering angle β. This determination is made, for example, according to a map as shown in FIG. In other words, the larger the steering angle β, the lower the threshold value a.
, b1c are each corrected to become larger. As a result, the smaller the turning radius, that is, the steeper the curve, the more strongly the downshift is suppressed. Furthermore, when the steering angle β is greater than or equal to the predetermined value β1, no correction is made to downshift the basic speed gear. Steps 110 to 120 are steps for correcting the basic gear stage as described above in accordance with the absolute value 1α1 of the inclination angle α. As is clear from the fact that the absolute value of the inclination angle α is taken, according to this control flow, as the inclination angle α becomes steeper both on uphill and downhill slopes, a stronger downshift is executed. It has become. As a result, above,
You can get stronger driving force when going uphill, and stronger engine braking when going downhill. After the basic gear position is corrected in steps 110 to 120 in this manner, a gear shift is performed to achieve the corrected gear position (step 122). As a result of the above control, during normal driving, only the main transmission section 2 is controlled to be in the basic gear determined according to the shift map, and information on changes in the tilt angle α and steering angle β is input. It becomes possible to execute detailed speed change control including the auxiliary transmission section 4 when the speed change is reached. Therefore, it becomes possible to precisely balance ensuring strong driving force on slopes and maintaining good stability on turning roads without bothering the driver. In the above embodiment, the sub-transmission section 4 is tilted at an angle of inclination α.
, the switching depended only on the steering angle β, but
When controlling the sub-transmission section 4, it is not prohibited to take other factors into consideration. Furthermore, as shown in FIG.
The degree of execution is changed according to the steering angle β (A type). However, the present invention is based on the "suppression" of the automatic transmission downshift based on the steering angle β (the downshift that should basically occur in the main transmission section based on the shift map), and the degree of this suppression is It is also possible to configure it so that it changes depending on the inclination angle α (Type B). Naturally, it is also possible to combine both of these concepts (C type).Which type should be selected in a specific example depends on the characteristics of the vehicle in question. You should make a decision after doing so.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the gist of the present invention, FIG. 2 is a schematic skeleton diagram of a vehicle automatic transmission to which an embodiment of the present invention is applied, and FIGS. 3(A) and (B) are the above-mentioned A diagram showing the engagement and release states of each clutch, brake, and one-way clutch in the main transmission section and sub-transmission section of the automatic transmission,
FIG. 4 is a flowchart showing the control flow used in the device of the above embodiment, FIG. 5 is a diagram showing an example of a map for determining threshold values a, b, and c, and FIG. FIG. 2... Main transmission section, 4... Sub-transmission section, 6... Computer, 61... Throttle sensor, 62... Vehicle speed sensor, 67... Tilt angle sensor, 68... Steering angle sensor.

Claims (1)

[Claims] (1) A main transmission section with a large difference in the gear ratio of each gear stage, and a main transmission part arranged in series with the main transmission part on the power transmission system, where the difference in the gear ratio of each gear stage is large. an automatic transmission comprising an auxiliary transmission section set to be smaller than the difference in gear ratio; means for detecting vehicle speed; means for detecting engine load; means for changing the speed of the main transmission section of the aircraft; means for detecting the slope angle of the running road; means for detecting the steering angle; and means for changing the speed of the auxiliary transmission section depending on the slope angle and the steering angle. means for causing the automatic transmission to downshift more strongly as the tilt angle is larger, and for suppressing the downshifting of the automatic transmission more strongly as the steering angle is larger. A downshift control device for vehicles equipped with automatic transmissions.