JP5194753B2 - Shift control device for vehicle transmission - Google Patents

Description

  The present invention relates to a shift control device that automatically controls a shift stage according to a vehicle running state in a vehicle equipped with a transmission having a plurality of shift stages.

  In recent vehicles, automation of various devices has progressed, and various automatic vehicle power transmission devices have been developed for power transmission devices in order to facilitate vehicle operation and reduce driver fatigue. ing. A typical example is an automatic transmission that combines a torque converter and a planetary gear mechanism, and is widely used as a power transmission device for so-called automatic vehicles (AT vehicles). In addition to the automatic transmission, a parallel shaft gear mechanism type transmission similar to a so-called manual vehicle (MT vehicle) is used, and this is combined with an automatic operation clutch, and automatically controlled according to the running state of the vehicle by an electronic control unit. There is a power transmission device that automatically switches the gear position. A transmission that automatically shifts using a parallel shaft gear mechanism type transmission is sometimes referred to as an AMT. Hereinafter, this transmission is referred to as a “parallel shaft gear mechanism type transmission for automatic transmission control”.

  There is a transmission loss in the torque converter of the automatic transmission, and the planetary gear mechanism and its control device are complicated and expensive. The automatic transmission control parallel shaft gear mechanism type transmission is combined with an automatic operation clutch and has no transmission loss due to the intervention of the torque converter, so it is superior to the automatic transmission in terms of fuel economy of the vehicle. The structure and control of the speed change mechanism are simpler and more reliable than the automatic transmission. Accordingly, a parallel shaft gear mechanism type transmission with automatic shift control that performs automatic shift operation with an actuator is often used in a truck that has a large load weight and places importance on fuel economy.

An outline of a power transmission device for a vehicle equipped with a transmission that automatically switches gears and the overall relationship between the control devices of each device will be described with reference to FIG.
In the vehicle shown in FIG. 3, an engine 1 and a transmission 2 are mounted as a power transmission device, and a clutch (wet multi-plate clutch) 3 is disposed therebetween. The engine 1 of this example is a diesel engine equipped with a fuel injection pump, and controls the fuel injection pump according to the depression amount of the accelerator pedal 11 operated by the driver, etc., and changes the fuel supply amount ( ECU) 12. Further, the transmission 2 of this example is a parallel shaft gear mechanism type multi-stage transmission for automatic transmission control, and includes an actuator 22 that is controlled by a transmission control unit (TCU) 21 and switches the shift stage. The output shaft of the transmission 2 is finally connected to a wheel 4, and a vehicle speed sensor 5 that detects the vehicle speed based on the number of rotations is installed on the wheel 4. The clutch 3 disposed in front of the transmission 2 has a clutch control unit (CCU) 31 that automatically connects and disconnects the clutch when the gear position is switched.

  Note that the power transmission device of FIG. 3 has a fluid coupling (fluid coupling) 6 interposed between the engine 1 and the clutch 3. The fluid coupling 6 does not have a torque amplifying function like a torque converter. However, by interposing this, the smooth start of the vehicle utilizing slip between the fluid coupling pump 61 and the turbine 62 can be achieved. It becomes possible. When the vehicle reaches a predetermined speed of about 10 km / h after starting, the pump 61 and the turbine 62 are integrally fastened by the lockup clutch 63, and the engine 1 is directly coupled to the clutch 3.

  The transmission control device 21 is provided with a shift speed determining means for determining a shift speed corresponding to a vehicle running state. The shift speed determining means includes a vehicle speed and an accelerator opening degree of the engine (a depression of the driver's accelerator pedal). The shift map as shown in FIG. 4 is stored. The shift map defines the shift speed region corresponding to the vehicle speed and the accelerator opening, and when the traveling state of the vehicle moves beyond the shift point line in the shift map to another shift speed region, The shift speed determining means outputs a shift command, and the transmission control device 21 operates the actuator 22 to change the shift speed. The optimal shift point when the vehicle is running differs between the shift-up when changing from a low speed to a high speed and the shift-down when changing from a high speed to a low speed. A shift point line corresponding to each of the downs is written. In other words, the target shift speed range determined by the vehicle speed and the accelerator opening of the engine is different between the shift-up case and the shift-down case. There will be a shift map and a shift-down shift map.

The gear position determination means using the shift map is not limited to the parallel shaft gear mechanism type transmission of automatic transmission control as shown in FIG. 3 but is also adopted in an automatic transmission. For example, Japanese Patent Application Laid-Open No. 63-167162 discloses a shift control device that controls a parallel shaft gear mechanism type transmission using a shift map, and Japanese Patent Application Laid-Open No. 2005-308096 controls an automatic transmission based on a shift map. A transmission control device is disclosed.
JP 63-167162 A JP 2005-308096 A

  If a shift is performed while the vehicle is running, the gear ratio of the power transmission system from the engine to the wheels changes and torque fluctuations occur, giving a shift shock to the driver. A shaft gear mechanism type transmission tends to be larger than an automatic transmission. As shown in FIG. 3, the parallel shaft gear mechanism type transmission is provided with a plurality of gear trains and a meshing clutch on the main shaft and the counter shaft arranged in parallel, and the meshing clutch is engaged and released. In this case, the clutch between the engine and the transmission is disconnected, and the transmission of engine power is cut off for a short time. Since the vehicle is decelerated by shutting off the engine power and re-acceleration is performed after the shift, the behavior at the time of the shift gives the driver a so-called feel and shift shock, and is referred to as “acceleration loss (torque loss)”. Deteriorating driving feeling. On the other hand, in an automatic transmission, since the gear stage is switched by changing the wet multi-plate clutch installed in the planetary gear mechanism, the engine power cut-off period is short, and the torque amplification function of the torque converter intervening in the power transmission system Torque fluctuations are absorbed to some extent. However, in order to improve fuel economy, the automatic transmission torque converter is directly connected (locked up) and unlocked its function when certain driving conditions are reached. Deterioration and driver discomfort increase.

In addition, in a transmission that automatically controls the shift speed using a shift map, for example, if a shift up occurs while the vehicle is traveling on an uphill road, the gear ratio of the transmission decreases due to the shift up, and the wheels are driven. The torque may decrease and the vehicle may decelerate significantly due to the slope resistance of the uphill road, resulting in a stalled state. This will be explained with reference to the shift map of FIG. 4. The speed of the vehicle in the second speed traveling state at point A increases due to an increase in the accelerator opening, etc., and moves to point B in the third speed region (shift-up map). Then, the gear stage shifts up and switches to the third speed. However, if the gear ratio of the transmission is reduced by switching to the third speed and the driving torque that overcomes the gradient resistance of the road surface is insufficient, the vehicle speed will decrease and the vehicle will stall, causing the vehicle to run against the driver's intention. It becomes a state. When the vehicle speed decreases and the vehicle running state again shifts to point C in the second speed region (shift down map), the gear is shifted down to the second speed. is there. When hunting occurs, a shift shock accompanying a shift occurs frequently, resulting in a deterioration in driving feeling and a heavy burden on the transmission and the transmission operating device.
The present invention relates to a transmission control device that automatically controls a shift stage of a transmission using a shift map, and prevents a shift shock and a loss of acceleration during a shift-up shift to prevent a deterioration in driving feeling, and It is an object of the present invention to avoid a vehicle stall associated with a shift up on an uphill road.

In view of the above-described problems, the present invention provides a transmission control device that switches a gear stage using a shift map, when the acceleration of the vehicle is small and the driving force of the vehicle after shifting is greater than the current driving force. Thus, the shift-up shift is allowed to prevent deterioration of driving feeling and vehicle stall on an uphill road. That is, the present invention
“A transmission control device for controlling the speed of a transmission mounted on a vehicle,
The transmission control device includes a shift speed determining means for determining a target shift speed corresponding to a vehicle speed of the vehicle and an accelerator opening of an engine mounted on the vehicle,
The transmission control device includes means for detecting the acceleration of the vehicle, and driving force calculating means for calculating the driving force of the vehicle based on the output torque of the engine and the shift speed of the transmission,
When the target shift speed determined by the shift speed determination means is higher than the current shift speed, the acceleration of the vehicle is equal to or less than a predetermined value and is calculated by the driving force calculation means. when the driving force in the target gear is greater than the driving force in the current shift speed target, it performs a shift to the high speed stage, when the acceleration of the vehicle is greater than a predetermined value, again by the gear-determining means Determine the gear position "
The transmission control device is characterized by this.

  According to a second aspect of the present invention, the driving force calculating means can determine the output torque of the engine using a torque map corresponding to the engine speed and the accelerator opening.

  According to a third aspect of the present invention, the present invention is suitable for a parallel-shaft gear mechanism type transmission in which a shift stage is controlled by the transmission control device.

The transmission control device according to the present invention includes a shift speed determining means for determining a target shift speed corresponding to the vehicle speed of the vehicle and the accelerator opening of the engine, that is, a shift speed determining means for determining the target shift speed by a shift map. The gear stage during vehicle travel is basically determined according to the vehicle speed and the accelerator opening. The transmission control apparatus according to the present invention includes means for detecting the acceleration of the vehicle, and driving force calculating means for calculating the driving force of the vehicle based on the output torque of the engine and the shift speed of the transmission. When the target shift speed determined by the shift speed determining means is higher than the current shift speed, the target speed determined by the shift speed determining means is within a range where the vehicle acceleration is smaller than a predetermined value. The upshift is performed on condition that the driving force at the stage is larger than the driving force at the current shift stage. As described above, in the transmission control device of the present invention, the shift is prohibited when the driver depresses the accelerator pedal and acceleration exceeding a predetermined value occurs in the vehicle. The upshift is permitted when the vehicle acceleration is in a small range, that is, when the vehicle is in a traveling state where the vehicle acceleration is substantially zero and can be ignored. When the acceleration of the vehicle can be ignored, the driving torque of the power transmission system is also relatively small, and even if the upshift is executed, there is no sudden deceleration at that time. Since the shift shock accompanying the engine power cut-off is reduced, it is possible to avoid the deterioration of the driving feeling.
Furthermore, in the transmission control device of the present invention, even if the target shift speed determined using the shift map requires upshifting, the actual shift is executed when the acceleration of the vehicle is very small. Therefore, it is not necessary to adjust the shift point of the shift map from the viewpoint of preventing the deterioration of the driving feeling. Therefore, the operation of determining the shift point of the shift map is simplified, and the time and labor required for creating the shift map can be saved.

  In the transmission control device of the present invention, the driving force at the target shift stage determined by the shift stage determining means is larger than the driving force at the current shift stage, that is, the vehicle driving force predicted after the shift is currently Upshifting is permitted when the driving force is greater than When this condition is satisfied, even if upshifting is performed, the driving force of the vehicle does not decrease after shifting, and the vehicle does not decelerate due to running resistance acting on the vehicle. Therefore, even when the vehicle is traveling on an uphill road and gradient resistance is acting, it is possible to prevent a situation where the vehicle falls into a stalled state or shift hunting occurs.

  Incidentally, the running resistance acting on the vehicle can be divided into acceleration resistance based on inertial force when the vehicle is accelerated, gradient resistance based on road surface gradient, air resistance acting on the vehicle body during running, and wheel rolling resistance. . The driving force of the vehicle is equal to the running resistance obtained by adding up these resistances. However, if the acceleration is zero, the acceleration resistance is also zero, and the driving force of the vehicle is in balance with the remaining gradient resistance and the like. In other words, in the transmission control device of the present invention, the driving force of the vehicle is in a state equal to the gradient resistance or the like before the upshift is executed, and the driving force after the shift exceeds the gradient resistance on the uphill road. As a result, the vehicle does not decelerate.

  According to a second aspect of the present invention, in the driving force calculating means for calculating the driving force of the vehicle, the output torque of the engine is determined using a torque map corresponding to the engine speed and the accelerator opening. The driving force of the vehicle is a value obtained by dividing the driving torque acting on the wheel by the wheel radius, and the driving torque can be obtained by multiplying the output torque of the engine by the gear ratio of the power transmission device (transmission, final gear, etc.). . Normally, a control device for a vehicle power transmission device stores a torque map that represents the characteristics of the engine speed and output torque with the accelerator opening as a parameter. Both the predicted driving force and the driving force at the current gear can be easily calculated.

  According to a third aspect of the present invention, the present invention is applied to a parallel shaft gear mechanism type transmission for automatic transmission control. The present invention can be applied to an automatic transmission as long as it is a transmission control device provided with a shift speed determining means for determining a shift speed based on a shift map. However, as described above, in a parallel shaft gear mechanism type transmission, an engine is used. Inhibition of driving feeling due to power interruption tends to be more severe than that of an automatic transmission, and the present invention for preventing deterioration of driving feeling is suitable for a parallel shaft gear mechanism type transmission for automatic transmission control.

  Hereinafter, an embodiment of a transmission control device of the present invention will be described with reference to the drawings. This embodiment is an application of the present invention to a parallel shaft gear mechanism type transmission for automatic transmission control, The basic configuration of the power transmission device and the operation of each device are not different from the conventional one shown in FIG. In other words, the transmission control device of the present invention receives a signal from the vehicle speed sensor 5 of the vehicle and a signal of the accelerator opening of the engine (the amount of depression of the accelerator pedal 11 by the driver) to obtain the vehicle speed and the accelerator opening. The gear position is determined based on the corresponding shift map. When a gear change signal is output from the transmission control device 21, the actuator 22 changes the gear accordingly.

The transmission control device of the present invention has a low vehicle acceleration and a current driving force of the vehicle after the shift in order to prevent deterioration of driving feeling at the time of upshifting and vehicle stall on an uphill road. A shift-up shift is permitted when the driving force is greater than the driving force, and the configuration and operation of the transmission control device will be described with reference to the flowchart of FIG.
In FIG. 1, when the flow for determining the gear position is started, in step S1, the vehicle speed V detected by the vehicle speed sensor and the accelerator opening A detected by the accelerator sensor are read. Next, in step S2, a target shift speed is determined corresponding to the read vehicle speed V and accelerator opening A using the shift map stored in the control device. The shift map used in the present invention is a map similar to the shift map shown in FIG. 4 used in the conventional transmission control device, and the shift-up shift point line and the shift-down shift point line are written. Yes. Since the target shift speed range is different between the shift-up shift map and the shift-down shift map, in step S2, the shift-up target shift speed Nd and the shift-down target shift speed Nd ' Are determined respectively. Steps S1 and S2 constitute the gear position determining means of the present invention.

  In step S3, the current shift speed Nr, which is the actual gear speed while the vehicle is running, is read. In steps S4 and S5, the target shift speeds Nd and Nd ′ determined by the shift speed determination means and the current shift speed are determined. Nr is compared. In step S4, it is determined whether or not the upshift target shift speed Nd is greater than the current shift speed Nr, that is, whether or not the vehicle traveling state requires upshifting. If the determination in step S4 is negative, it is determined in step S5 whether or not the target gear stage Nd ′ for downshifting is smaller than Nr. If Nd ′ is smaller than Nr, the process proceeds to step S6 to shift gears. The machine control device outputs a downshift command. If the determination in step S5 is negative, the current gear stage is in a state where neither upshifting nor downshifting is required, so the flow is terminated without outputting a gear shift command.

If the determination in step S4 is Yes and the target gear stage Nd for upshift determined corresponding to the vehicle speed V and the accelerator opening A is higher than the current gear stage Nr, the present invention In this transmission control device, it is determined whether or not the running state of the vehicle is within a range in which upshifting is permitted. In this determination, first, in step S7, a differential calculation of the vehicle speed signal from the vehicle speed sensor is performed to obtain the longitudinal acceleration α of the vehicle. In step S8, the absolute value of the computed acceleration alpha executes judgment whether less than a predetermined value alpha _0. The predetermined value α ₀ is set to a small value in the vicinity of 0, specifically about 0.2 to 0.4 m / ss. When the acceleration α exceeds the predetermined value, an upshift command is output. End the flow without prohibiting upshifting. The predetermined value alpha _0, to become a little larger when the accelerator opening degree A is greater may be set as a function of the accelerator opening.

When the absolute value of the acceleration alpha is determined to be smaller than the predetermined value alpha ₀ in step S8, the process proceeds to step S9, which is a driving force calculating means of the present invention, calculates the driving force of the shift-up before and after the vehicle. The calculation procedure will be described below.
The driving force F of the vehicle is expressed by the following equation, where T is the engine output torque, r is the gear ratio of the power transmission device including the transmission, and R is the wheel radius.
F = T × r / R
Normally, a control device for a vehicle power transmission device stores a torque map as shown in FIG. 2 that represents the characteristics of the engine speed n and the output torque T with the accelerator opening A as a parameter. The engine output torque T when the accelerator opening A is constant has a characteristic of decreasing in accordance with an increase in the engine speed n in a normal use region. Since the engine output torque is substantially determined by the amount of fuel injected into the engine, it is stored in the engine control unit (ECU) when the vehicle control unit is not equipped with a torque map. Further, the output torque T can be obtained using a map that determines the fuel injection amount corresponding to the accelerator opening and the engine speed.

  The engine speed n is proportional to the vehicle speed V if the gear ratio r is constant. When a shift-up shift is performed and the shift speed is switched to a high speed, the gear ratio r decreases, and the vehicle speed V hardly changes during the short-lasting time, so the engine speed n decreases. The gear ratio r is a known value set corresponding to the gear position, and is determined based on the current gear ratio r (Nr) of the gear speed Nr, the gear ratio r (Nd) of the target gear speed Nd, and the vehicle speed V. The engine speed n (Nr) of the engine and the engine speed n (Nd) when shifted up can be respectively calculated. As for the engine output torque, the output torque T (Nr) at the current gear stage and the output torque T (Nd) predicted after the upshift are obtained corresponding to the respective engine speeds from the torque map of FIG. However, the output torque T (Nd) after the shift-up when the accelerator opening A is constant is higher than the current output torque T (Nr).

In step 10, the vehicle driving force at the current gear stage Nr and the vehicle driving force at the target gear stage Nd are compared to determine whether the vehicle driving force after the upshift is greater than the current driving force. To do. This comparison ultimately determines whether or not the following equation holds.
T (Nd) × r (Nd) ≧ T (Nr) × r (Nr)
If the determination in step 10 is Yes, the vehicle driving force does not fall below the current driving force even if the vehicle is shifted up to the target gear stage Nd, so that the vehicle in which the acceleration is zero is not decelerated. Therefore, the transmission control device outputs an upshift command to the actuator (step 11). If the determination in step 10 is negative, the flow is terminated without outputting the upshift command, and the upshift is prohibited.

  In the transmission control device of the present invention, the conditions for allowing the upshifting are first when the absolute value of acceleration is a small value near zero, and is limited to a traveling state in which the vehicle speed hardly changes. In such a state, the transmission torque for driving the vehicle in the power transmission system is small, and even if the power transmission state changes at the time of upshifting, the shift shock is small, resulting in a deterioration in driving feeling accompanying the upshifting. There is nothing. In particular, in the automatic transmission control parallel shaft gear mechanism type transmission that disengages the clutch and executes the upshifting, even if the engine power is cut off, there is no sudden deceleration feeling, and the driver feels that the acceleration is missing. Will not give.

  Further, the transmission control device of the present invention is provided with driving force calculating means for calculating the driving force of the vehicle based on the output torque of the engine and the shift speed, and the driving force of the vehicle predicted after the shift is the current driving Shift up is allowed when greater than force. When this condition is satisfied and the acceleration can be ignored, the vehicle will not decelerate due to the running resistance acting on the vehicle even if the upshift is performed. Therefore, even when the vehicle is traveling on an uphill road and the gradient resistance is acting, it is possible to prevent a situation where the vehicle stalls due to a shift-up or shift hunting occurs.

  As described in detail above, the present invention is a transmission control device that switches gears according to a shift map, and shifts when the acceleration of the vehicle is small and the driving force of the vehicle after shifting is greater than the current driving force. By allowing the upshift, the driving feeling is deteriorated and the stall on the uphill road is prevented. Therefore, if the transmission control device of the present invention is a control device using a shift map, it can be applied to any automatic transmission or a parallel shaft gear mechanism type transmission for automatic transmission control, or is not limited to a diesel engine. Needless to say, the present invention can also be applied to a vehicle equipped with a gasoline engine. In the above embodiment, the current engine speed and output torque are obtained by calculation and using a torque map. However, the engine speed sensor, the torque detector, and the like are used to obtain these values. It is clear that changes can be made.

It is a flowchart which shows the action | operation of the transmission control apparatus of this invention. It is a figure showing the torque map used in the Example of this invention. It is a figure which shows the power transmission device in a vehicle, and its control apparatus. It is a figure which shows the shift map of a transmission control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 11 Accelerator pedal 2 Transmission 21 Transmission control apparatus 22 Actuator 3 Clutch 31 Clutch control apparatus 5 Vehicle speed sensor S1-S11 Each step of control flow

Claims (3)

A transmission control device for controlling a shift stage of a transmission mounted on a vehicle,
The transmission control device includes a shift speed determining means for determining a target shift speed corresponding to a vehicle speed of the vehicle and an accelerator opening of an engine mounted on the vehicle,
The transmission control device includes means for detecting the acceleration of the vehicle, and driving force calculating means for calculating the driving force of the vehicle based on the output torque of the engine and the shift speed of the transmission,
When the target shift speed determined by the shift speed determination means is higher than the current shift speed, the acceleration of the vehicle is equal to or less than a predetermined value and is calculated by the driving force calculation means. when the driving force in the target gear is greater than the driving force in the current shift speed target, it performs a shift to the high speed stage, when the acceleration of the vehicle is greater than a predetermined value, again by the gear-determining means A transmission control apparatus for determining a gear position. The transmission control device according to claim 1, wherein the driving force calculating means determines an output torque of the engine based on a torque map corresponding to an engine speed and an accelerator opening. The transmission control device according to claim 1, wherein the transmission is a parallel shaft gear mechanism type transmission that controls a gear position by the transmission control device.

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