JPH02253051A - Automatic transmission gear control device - Google Patents

Abstract

PURPOSE:To make an engine brake compatible by prohibiting the use of the maximum speed stage at the time of an accelerator not being stepped on, a brake being stepped on and the car speed at which an engine does not overrun even by the speed change to the gear stage which is one stage lower than the maximum speed stage. CONSTITUTION:A controller 10 inputs the signals of a select lever sensor 12, an accelerator sensor 14, a brake sensor 16, a gear stage detecting sensor 7, a car speed sensor 9 and an engine rotation sensor 2, and sets a flag 10-1 for prohibiting the use of the maximum speed stage at the time of an accelerator 13 not being stepped on, a brake 15 being stepped on, and the car speed at which an engine 1 does not overrun even if a transmission gear 5 is speed- changed to the gear stage which is one stage lower than the maximum speed stage (or the OD stage). When the accelerator 13 is stepped on or the fixed range is selected, the flag 10-1 is released. The engine brake is thus made compatible at the time of control during the high speed running so as to reduce the abrasion of a foot brake.

Description

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

The present invention is an automatic transmission system that applies engine braking even when driving in the automatic transmission range when driving at high speed and when braking is required.

[Conventional technology]

There are automatic cars that are equipped with a friction-type automatic clutch and automatic transmission, and are controlled by a controller consisting of a microcomputer or the like. In such an automatic vehicle, a shift range can be selected using a select lever, and the shift range can be broadly classified into a fixed range and an automatic shift range. If you select a fixed range, the vehicle will drive in a specific gear. For example, if the "1" range is selected, the vehicle will run in first gear. When the automatic shift range rl)J is selected, the controller selects the optimum gear based on the vehicle driving conditions, engine conditions, etc., and automatically shifts the gears. Selection of the optimum gear stage is performed according to a predetermined shift diagram. FIG. 5 shows an example of such a shift diagram. The horizontal axis is the vehicle speed, and the joint axis is the accelerator depression amount. In FIG. 5, curve A indicates the boundary when shifting up from 1st speed to 2nd speed. When the operating point determined by the vehicle speed and the amount of accelerator depression moves across curve A from left to right, 1
It will automatically shift up from 1st gear to 2nd gear. Similarly, the curve opening indicates the boundary when shifting up from 2nd speed to 3rd speed, and the boundary when shifting up from 3rd speed to 4th speed. Note that the curve in FIG. 5 is for upshifting. Therefore, even if the operating point crosses curve A from right to left, it does not mean that the gear is downshifted from second gear to first gear. In order to provide hysteresis to the gear shifting operation, another curve (not shown) is prepared for downshifting. In addition, as a conventional document regarding an automatic transmission control device, there is Japanese Patent Application Laid-Open No. 100023/1983.

[Problem to be solved by the invention]

(Problem) With the conventional technology described above, engine braking cannot be applied when the vehicle is running in the automatic transmission range, so the burden is placed only on the foot brake, which causes severe wear on the brake lining and brake pads. was there. (Explanation of the problem) When attempting to apply engine braking, it is customary for drivers to take their foot off the accelerator pedal. However, when driving in the automatic transmission range, the vehicle may end up shifting up. For example, in FIG. 5, vehicle speed N1. Accelerator depression amount P
The operating point when the vehicle is running at 1 is A, but when the accelerator pedal is released in this state, the operating point shifts to B. At this time, since the vehicle crosses curve C and enters the 4th gear region, the gear is shifted up from 3rd gear to 4th gear. Shifting up would disappoint the driver's expectations of applying engine braking. The driver has no choice but to apply the foot brake. At low and medium speeds, the degree of wear on fund brakes is small, but when used at high speeds, the wear is large. This is because the kinetic energy of a vehicle is related to the square of the vehicle speed, and a large braking force is required to stop a vehicle running at high speed. Additionally, some vehicles are equipped with an overdrive gear (hereinafter referred to as rOD) with a gear ratio of 1 or less as the highest speed gear in order to reduce engine speed and improve fuel efficiency when driving at high speeds. . An overdrive switch is provided which is a switch for selecting whether or not to use the OD stage. If you are driving in OD gear, you cannot expect engine braking, so if you want engine braking to work, turn off the overdrive switch and do not use OD gear. Then, even at high speed, 1
The vehicle will run in the lower gear, which has the effect of engine braking. However, the overdrive switch is cumbersome to operate because the driver has to switch it each time while judging the driving situation, and it cannot be said to be fully utilized to reduce the burden on the foot brake. An object of the present invention is to solve the above-mentioned problems.

[Means to solve the problem]

In order to solve the above problem, in the present invention, even if braking at low speeds and medium speeds is left to the foot brake, when braking at high speeds where the foot brake is severely worn,
The following measures were taken to obtain an engine braking effect by running the vehicle in a gear that is one gear lower than the OD gear (or the highest speed gear for vehicles without an OD gear). That is, in the automatic transmission control device of the present invention, even if the accelerator pedal is not depressed, the brake pedal is depressed, and the gear is shifted to a gear one gear below the highest gear, the engine does not run at a vehicle speed that does not run smoothly. It was decided to provide a means for prohibiting the use of the highest gear at a certain time, and a means for canceling the prohibition of the use of the highest gear when the accelerator pedal is depressed or a fixed range is selected.

[For production]

According to the above-mentioned automatic transmission control device, it is determined whether engine braking is likely to be required while driving in the automatic transmission range by checking the driver's intention and the vehicle situation. . The driver's intention is checked in two ways: ■Whether the accelerator pedal is depressed, and ■Whether the brake pedal is depressed. If you press the gas pedal, it means you want to accelerate, so there is no need for engine braking. If you keep your foot firmly pressed down on the brake pedal, that's exactly when you need engine braking assistance. Adding engine braking reduces the burden on the foot brakes, reducing wear on brake linings and brake pads. The vehicle status is checked to see if the vehicle speed is such that the engine will not overrun even if the gear is shifted to one gear below the OD gear (or the highest gear). When the vehicle speed is such that it would normally be running in OD gear (or highest gear), the effect of engine braking comes out because it is running in the gear one gear lower, but if you shift to that gear, It would be a problem if the engine speed was too high and the engine went into overrun condition. This is because even if the foot brake is less damaged, the engine is more likely to be damaged. As a result of checking the driver side and the vehicle side, if it is determined that there is no problem in using the gear one step below for engine braking, the O
Prohibits use of D gear (or highest speed gear). As a result, when the vehicle is automatically shifted to the OD gear (or the highest gear), the vehicle is driven in a gear one gear lower than the OD gear (or the highest gear), and engine braking is applied. On the other hand, when the fixed range is selected by the select lever or when the driver is depressing the accelerator pedal, the use of the OD gear (or the highest speed gear) is not prohibited. This is because, in the case of a fixed range, there is no relation to the shift diagram shown in FIG. 5, and there is no possibility that an upshift will occur when the accelerator pedal is released. Furthermore, if the accelerator pedal is pressed down, the driver has the will to accelerate, so there is no need to apply engine braking.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. (First Embodiment) FIG. 1 shows an automatic transmission control device according to a first embodiment of the present invention. In Fig. 1, 1 is the engine, 2 is the engine speed sensor, 3 is the clutch, and 4 is the clutch.
Actuator, 5 is a transmission, 6 is a transmission actuator, 7 is a gear stage detection sensor, 8 is a drive shaft, 9 is a vehicle speed sensor, 10 is a controller, 10-1 is a prohibition flag, 11
is the select lever, 12 is the select lever sensor, 13
1 is an accelerator pedal, 14 is an accelerator sensor, 15 is a brake pedal, and 16 is a brake sensor. The clutch actuator 4 controls whether the clutch 3 is engaged or disengaged in response to a signal from the controller 10 . The transmission actuator 6 shifts gears in response to a signal from the controller 10. Gear stage detection sensor 7
detects which gear is currently in use. The select lever 11 is a lever for selecting various fixed ranges or automatic shift ranges. FIG. 3 is a flowchart for explaining the control operation of the first embodiment. This flowchart is repeatedly executed at extremely short time intervals (for example, several tens of meters). Item numbers ■ to ■ in the following explanation refer to steps ■ in Figure 3.
It corresponds to ~■. ■ Read signals related to select lever range, vehicle speed, engine speed, accelerator depression, and brake depression. These signals are sent to the select lever sensor 12 vehicle speed sensor 9. Engine speed sensor 2. It is obtained from the accelerator sensor 14 and the brake sensor 16. ■ Recognize which gear is currently in use. This is done by reading the signal from the gear stage detection sensor 7. ■ Check whether you are driving in the automatic transmission range. This is done by examining the signal from the select lever sensor 12. ■ The fact that the vehicle is not in an automatic transmission range means that it is running in a fixed range. In this case, the prohibition flag 10-1 set in the controller 10 is reset. The prohibition flag 10-1 is O when it is set.
This means that the use of the D gear (or the highest speed gear) is prohibited, and is not prohibited when it is reset. ■ Since the vehicle is running in a fixed range, processing operations are performed according to that range. For example, when the fixed range of "1" is selected,
Travel is performed while maintaining the first gear. ■ Check whether the accelerator pedal is pressed. This determines whether the driver has the intention to accelerate. In other words, you can run eight laps to see if you have the will to reduce engine braking. When you press the accelerator pedal to accelerate, it is determined that there is no intention to apply engine braking. This step, along with step (3), is a step to check whether it is necessary to prepare for engine braking by looking at the driver's side. Step (2) that comes after this is a step to investigate by approaching the vehicle side. - If it is determined that there is no intention to apply the engine brake, the prohibition flag 10-1 is reset. This is because in this case, there is no need to prohibit the use of the 00th gear (or the highest speed gear). ■ Check whether the brake pedal 15 is depressed. Naturally, it would be convenient if the engine brake also worked while the pedal was being stepped on. This is because the burden on the mat brake is reduced accordingly. ■ Check to see if the engine will overrun if you downshift one gear at the current vehicle speed. Engine speed can be calculated from the gear ratio after downshifting, vehicle speed, etc., so check based on that. If the engine overruns, you need to give up on engine braking. [Phase] If there is no overrun even after downshifting, set the prohibition flag 10-1. This means that the use of the OD gear (or the highest speed gear) is prohibited, and the conditions for applying engine braking have been established. (2) Check whether the prohibition flag 10-1 is set. @ If the prohibition flag 10-1 is cent, the OD gear (or highest speed gear) cannot be used. Therefore, automatic shift range processing operations (processing to determine the optimum gear stage) such as shift amplifier operation according to the shift diagram shown in Fig. 5 are performed only when the OD stage (or highest speed stage) is not used. It will be held in For example, in Figure 5, where 4th gear is the highest gear, if you release your foot from the accelerator pedal when the gear is at
The engine will shift from speed to 4th gear, but if the use of 4th gear is prohibited, it will remain in 3rd gear and apply engine braking. - When the prohibition flag 10-1 is reset, there is no need for engine braking. Therefore, the use of OD gear (or highest speed gear) is not prohibited. The processing operation of the automatic shift range is performed including the OD gear (or the highest gear). [Phase] Check whether gear shifting operation is necessary. This is the optimal gear determined in step @3■,
This is done by comparing the current gear position recognized in step (3). If they match, there is no need for a shift operation; if they do not match, it is necessary. - When a gear shift operation is not required, it is sufficient to maintain the current gear position, so the clutch 3 is controlled accordingly. [Phase] Perform gear change operation. The gear shifting operation involves driving the clutch actuator 4 to disengage the clutch 3, driving the transmission actuator 6 to perform a gear shift, and then driving the clutch actuator 4 again to disengage the clutch 3. (Second Embodiment) FIG. 2 shows an automatic transmission control device according to a second embodiment. Reference numbers correspond to those in FIG. 1. The difference is that a counter 10-2 is provided in the controller 10.
This is the point where we set . In this embodiment, when the prohibition flag 10-1 is set, even if the accelerator pedal 13 is depressed, it is not reset immediately as in the first embodiment, but is reset only after a predetermined period of time has elapsed. . (・This was done to avoid this. The reason for this is that if the use of OD gear (or highest gear) is prohibited or canceled too often, the durability of the structural parts related to gear shifting will deteriorate. Depending on the road you are traveling on, you may have to operate the accelerator pedal 13 and brake pedal 15 alternately and frequently.For example, on a winding road (a winding road ), or when driving in a city area.In such a case, in the first embodiment, the brake pedal 15
The prohibition flag 10-1 is set when you step on the accelerator pedal 13, and is reset when you press the accelerator pedal 13. Therefore, the use of the OD gear (or the highest gear) is prohibited and canceled too often, and structural parts related to gear shifting are damaged. Durability may deteriorate. Therefore, a counter 10-2 is provided to prevent the prohibition flag 10-1 from being reset until a predetermined period of time has elapsed since the accelerator pedal 13 was depressed. Case,! ＝There is also a method of not setting it until a predetermined period of time has elapsed, but it is better to prioritize and maintain the state in which the engine brake is effective (until the predetermined period of time elapses, the prohibition flag is set to 1).
A method of maintaining 0-1 cents) is fail-safe and desirable. FIG. 4 is a flowchart for explaining the control operation of the second embodiment. Steps ① to [phase] correspond to steps with the same numbers in FIG. Therefore, a description of those steps will be omitted. The newly added steps are steps C-■, C-■, C-■, and C■ regarding counter 1.degree.2. The counter 10-2 starts counting up when the accelerator pedal 13 is depressed in the automatic shift range. Therefore, if this is not the case, that is, if the automatic shift range is not set, or if the accelerator pedal 13 is not depressed, the counter 10-2 is cleared. Steps C-1 and C-2 do this. The time elapsed since the accelerator pedal 13 was depressed can be measured by the count number of the counter 10-2. This is because the flowchart is executed at a fixed short time interval T (for example, T - several tens of meters), and as long as the accelerator pedal 13 is kept pressed, the count is incremented by 1 each time the flowchart is executed, and the count is M. and MX
It can be seen that time T has elapsed. When the value (M) of the counter 10-2 reaches the set value (in other words, when a predetermined period of time has elapsed), the prohibition flag 10-
1 (step ■). The larger the set value is, the less frequently the use of the OD gear (or the highest gear) is inhibited and canceled, which is preferable in terms of improving the durability of structural parts related to gear shifting. However, if it is made too large, the engine braking condition may still be maintained even though it is no longer necessary to apply the engine brake, which is undesirable. Therefore, the size of the set value is determined by comprehensively considering these circumstances.

【Effect of the invention】

As described above, the present invention provides the following effects. ■ Even if you are driving at such high speed that the OD gear (or the highest gear) is used in the automatic gear range, if the predetermined conditions such as the brake pedal being depressed are not met, the OD shift will occur.
It is now possible to prohibit the use of the highest gear (or the highest gear), drive in the next lower gear, and apply engine braking. Therefore, it has become possible to use engine braking in conjunction with braking during high-speed driving, where foot brake wear is severe, making it possible to reduce foot brake wear. (2) If the OD gear (or highest gear) is maintained in a prohibited state until a predetermined time has elapsed after the accelerator pedal 13 is depressed in the automatic shift range, the following effects will also be obtained. First, even if you release the brake pedal 15, °ζ
This has the effect that engine braking force can be maintained for a while (in the first embodiment, it immediately stops working). Second, even if you press the accelerator pedal 13 thickly (depressing it) to accelerate, it will not shift up to the OD gear (or the highest gear), but will stay at the gear one gear below. This has the effect of providing powerful driving force.

[Brief explanation of drawings]

Fig. 1: Automatic transmission control device according to the first embodiment of the present invention Fig. 2: Automatic transmission material filling device according to the second embodiment of the present invention Fig. 3: Flowchart for explaining the control operation of the first embodiment. FIG. 4. Flowchart for explaining the control operation of the second embodiment. FIG. 2 is an engine rotation speed sensor, 3 is a clutch, 4 is a clutch actuator, 5 is a transmission, 6 is a transmission actuator, 7 is a gear detection sensor, 8 is a drive shaft, 9 is a vehicle speed sensor, 10 is a controller, 10 -1 is a prohibition flag, 10-2 is a counter, 11
is the select lever, 12 is the select lever sensor, 13
1 is an accelerator pedal, 14 is an accelerator sensor, 15 is a brake pedal, and 16 is a brake sensor. Patent applicant: Izu-゛Jidosha Co., Ltd. Representative Patent Attorney Tomio Honjo, Procedural Principal (spontaneous)

Claims (1)

[Claims] A means of prohibiting the use of the highest gear when the accelerator pedal is not depressed, the brake pedal is depressed, and the vehicle speed is such that the engine will not overrun even if the gear is shifted to one gear below the highest gear. and means for canceling prohibition of the use of the highest speed gear when the accelerator pedal is depressed or a fixed range is selected.