JPH0756341B2 - Engine brake controller for continuously variable transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an engine brake control device for a continuously variable transmission, which is preferably applicable when the continuously variable transmission is used as a transmission for an automobile.

[Prior Art] When driving a car, it is indispensable for the running stability to apply the engine braking on a curve or downhill. In order to develop the engine braking torque, the gear change lever is switched to the low speed position while the clutch is disengaged in the manual vehicle, and the selector lever is switched to the low speed position in the automatic vehicle.

[Problems to be Solved by the Invention] However, the engine braking torque obtained in this way becomes unique by the gear ratio peculiar to the new position and the vehicle speed at that time, and the driver arbitrarily adjusts it. It is not possible. That is, the gear ratio is set step by step for each position, and a large opening occurs between engine braking torques depending on which position is selected, so the driver selects a position that is not inappropriate as much as possible. I just try to do it. However, at the position once selected, a uniform engine brake torque is generated according to the vehicle speed when the vehicle is in the non-accelerated state, and therefore the driver has no choice but to rely on the brake pedal when further braking is required. For this reason, there is a problem that it is difficult to ensure sufficient running stability on a curve or a downhill. In addition to such a problem, this type of vehicle also has a problem that a dangerous state is likely to occur due to a delay in operation of a shift lever or a brake pedal. On the other hand, in the vehicle currently equipped with the continuously variable transmission, the shift control is merely programmed in relation to the vehicle speed, etc., and engine brake torque hardly occurs even if the accelerator is opened, Even if it happens, there is no change in the point that the driver does not want it.

The present invention has been made in view of such a problem, and is premised on using a continuously variable transmission capable of continuously changing a speed ratio, and The purpose is to develop and apply an engine brake control device that can positively change the engine brake torque with a simple operation even during non-acceleration.

[Means for Solving the Problems] The present invention adopts the following configuration in order to achieve such an object.

That is, the engine brake control device for a continuously variable transmission according to the present invention, as shown in FIG. 1, is an accelerator opening change region (a non-acceleration which is commonly called "play") that makes the throttle opening zero. Region), a detecting means for detecting the angular deviation from the maximum opening degree to the current accelerator opening degree as an offset amount, and the offset amount is inputted from this detecting means, and the engine brake torque changes in accordance with the increase or decrease of the offset amount. Thus, the control means for controlling the speed ratio of the continuously variable transmission is provided.

[Operation] With such a configuration, when the offset amount of the accelerator changes, a new offset amount is detected by the detection means, and the control means continuously changes the engine brake torque in response to the increase or decrease of the offset amount. Control the speed ratio of the transmission. Therefore, the driver can positively adjust the engine braking torque only by depressing the accelerator even when the vehicle is not accelerating, and can easily pull in such a decelerated state even from the acceleration region.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 2 to 6.

As shown in FIG. 2, a continuously variable transmission 1 for a vehicle to which this embodiment is applied is a variable displacement hydraulic pump driven by an engine 3 whose output changes according to the amount of depression of an accelerator pedal 2. 4 and a hydraulic motor 6 that drives the wheels 5 with the hydraulic fluid discharged from the hydraulic pump 4. The speed ratio e can be adjusted steplessly by changing the capacity of the hydraulic pump 4. Also,
This vehicle is equipped with a mode selector 7 shown in FIG. The mode selector 7 has two engine braking control modes E _B1 , E in addition to the parking mode P, reverse mode R, neutral mode N, drive mode D.
_B2 is set. Then, when the shift lever 8 is set to either of the engine brake control modes E _B1 and E _B2 , the engine brake control device according to the present embodiment operates.

In constructing the engine brake control device, the accelerator pedal 2 is provided with a relatively wide accelerator opening change region A in which the throttle opening θ ₂ is zero, as shown in FIG. This accelerator opening change area A
Is a portion excluding the throttle opening change area θ ₂ from the total accelerator opening change area θ ₁ and θ in the area A
The angular deviation from the opening at which ₁ is the maximum to the current accelerator opening is set as the offset amount α. A detector 9 shown in FIG. 2 is arranged around the accelerator pedal 2 to detect the offset amount α, and a detector V for detecting the vehicle speed V around the traveling wheels 5. 10 are arranged. Appropriate sensors such as potentiometers, rotary encoders, and tachogenerators are used as the detection means 9 and 10. Also,
The microcomputer 11 is provided with a microcomputer 11 as a control means for inputting the detection values α, V extracted from both the detection means 9, 10 and outputting an appropriate shift control signal x to the continuously variable transmission 1. , A memory 13, a well-known one equipped with an interface 14,
Stores the program that controls 2. According to this program, the CPU 12 sequentially inputs the detected values α, V,
A predetermined calculation for determining the speed ratio e is performed based on the data stored in the memory 13 in advance, and the control signal x for realizing the speed ratio e is output from the continuously variable transmission 1. It outputs to the hydraulic pump 4, and the capacity can be changed appropriately.

FIG. 5 is a flow chart showing the outline of the program. The operation of this embodiment will be described below with reference to this flowchart. When the program starts, it is first determined in step 21 whether the mode selector 7 is in the drive mode D or not. If YES, the routine proceeds to the normal traveling routine 22. This routine 22 is composed of a program for controlling the speed ratio e in the drive mode D, and calculation by a general method is performed. Then, after the shift control is executed, the process returns. If NO in step 21, step 23
Then, it is determined whether the mode selector 7 is in the E _B1 mode. YES
If k = k _{1 in} step 24 (k will be described later)
In the case of NO, k = k ₂ is set in step 25, and the process proceeds to step 26 to read the vehicle speed V and the offset amount α into the CPU 12. Then, in step 27, it is first determined whether the vehicle speed V is 10 km / h or less. In the case of YES, it is difficult to generate an effective engine brake torque no matter how the speed ratio e is controlled, and rather, the inconvenience such as the engine 3 being blown up is more serious. Therefore, the engine brake control according to the present invention is not performed. , And shifts to the normal traveling routine of step 22. If NO, the speed ratio e is calculated in step 28.

The arithmetic expression at this time is set as follows. First, as shown in FIG. 2, assuming that the torque generated on the input shaft 1a of the continuously variable transmission 1 is the engine brake torque T _E and the torque generated on the output shaft 1b is the wheel torque T _H , the engine performance when the accelerator is opened is shown. From the curve (see FIG. 6), it is possible to formulate a linear approximation formula T _E = C ₁ × S _E (1) C ₁ is a coefficient and S _E is the engine speed. Further, the following two equations are also established in the continuously variable transmission 1 with C ₂ as a coefficient.

T _H = T _E / e (2) V = C ₂ × e × S _E (3) where the engine brake torque T _E is the accelerator pedal 2
In order to correspond to the offset amount α of, T _H = k × α (4) is defined. k is determined according to whether the driver selects the E _B1 mode or the E _B2 mode with the select lever 8 in advance, takes a value of k ₁ or k ₂ , and affects the effectiveness of the brake (k ₁ <k ₂ ). As a result, (1) to
From the equation (4), e = {V / (k × C ₂ × α)} ^1/2 (5) is obtained. The CPU 12 calculates e by this equation (5).

Then, in step 29, the control signal x for realizing the speed ratio e is output to the hydraulic pump 4, and the flow returns after execution.

However, with such a configuration, even in the non-acceleration state, a braking effect corresponding to the offset amount α of the accelerator pedal 2 as defined by the equation (4) is generated,
The driver can positively change the engine brake through the offset operation. Therefore, the engine brake that matches the driving feeling of the driver can be applied at will, and the running stability can be improved. Further, since such control is performed through the accelerator operation, it is possible to easily shift to such a deceleration state even from the acceleration region, and the operability becomes excellent.

It should be noted that the coefficients in the above-described arithmetic expressions should be determined in practical use, and other correction coefficients and the like can be added as appropriate. Further, the calculation result may be previously made into a map or the like. Furthermore, the hydraulic pump side of the continuously variable transmission is fixed, the hydraulic motor side is of a variable displacement type, or both are variable, etc.
Various modifications can be made without departing from the spirit of the present invention.

EFFECTS OF THE INVENTION Since the engine brake control device of the present invention is configured as described above, by applying it to a vehicle equipped with a continuously variable transmission, the accelerator pedal can be operated without complicated operation of the brake pedal during non-acceleration. It is now possible to change the engine braking torque and apply braking based on one's own will only by offsetting operation.Through such a function, driving stability on curves and downhills can be improved, operation delays, etc. It is possible to surely reduce the risk due to.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of the present invention. 2 to 6 show an embodiment of the present invention, FIG. 2 is a schematic circuit diagram, FIG. 3 is a plan view of a position selector, FIG. 4 is an explanatory diagram of an offset amount, and FIG. Is a flowchart and FIG. 6 is a graph showing a characteristic curve of the engine. e ... Speed ratio θ ₁ ... Accelerator opening θ ₂ ... Throttle opening A ... Change area α ... Offset amount T _E ... Engine brake torque 1 ... Continuously variable transmission 2 ... Accelerator pedal 9 ... Offset amount detecting means 11 ... Control means (Microcomputer)

Claims (1)

[Claims] 1. A throttle opening, which is applied to a vehicle equipped with a continuously variable transmission configured so that a speed ratio represented by an output speed / an input speed can be changed steplessly. The detection means for detecting the angular deviation from the maximum opening to the current accelerator opening as an offset amount in the accelerator opening change region where 0 is set to 0, and the offset amount is input from this detecting means, and the engine brake torque is set to the offset amount. And a control means for controlling the speed ratio of the continuously variable transmission so as to change in accordance with the increase or decrease of the.