JP3365304B2 - Shift control device for vehicle with continuously variable transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a control device for a vehicle having a continuously variable transmission capable of continuously changing a gear ratio, and more particularly to a control device for a vehicle at the end of a gear shift. The present invention relates to a shift control device that performs control to suppress the expected longitudinal vibration of the vehicle. 2. Description of the Related Art Recently, a continuously variable transmission has been adopted as a transmission for a vehicle. This type of continuously variable transmission is configured to continuously change the gear ratio by changing the groove width between the input side pulley and the output side pulley around which the belt is wound, that is, the belt winding radius. Or by inclining the power rollers sandwiched between the input side disk and the output side disk each having a toroidal surface to change the radius of the contact position of the power roller with each disk, thereby changing the gear ratio. It is configured to change continuously. The gear ratio is determined by, for example, an accelerator pedal depression angle (accelerator opening) signal indicating a driver's output request, an output request signal from a cruise control that maintains the vehicle speed at a constant vehicle speed, and a vehicle speed. It is controlled based on the running state of the vehicle. Therefore, when there is an acceleration request due to depression of an accelerator pedal or the like, the gear ratio is controlled to be increased. This is because, in a belt-type continuously variable transmission, the width of the belt on the input side pulley is increased to gradually reduce the winding radius of the belt, and at the same time, the width of the output side pulley is reduced to reduce the belt winding radius. Is performed by increasing. Further, the gear ratio finally set at that time is determined based on the target rotation speed of the prime mover, the vehicle speed, and the like which are determined based on the degree of the output increase request. In the case of such a so-called power-on downshift, inevitable torsion occurs in a power transmission system such as a propeller shaft, and the number of revolutions increases at a predetermined rate. At the end of the reached shift, the torsional torque or the inertia torque may cause a drive torque thrust (overshoot) and a longitudinal vibration (shake) of the vehicle. In order to prevent or suppress the longitudinal vibration of the vehicle at the end of the shift, it is effective to change the change in the driving torque associated with the shift immediately before the end of the shift. No. 8-177997. The device described in this publication is configured to temporarily reduce the speed ratio immediately before the end of the speed change for increasing the speed ratio. That is, in this device, the time when the speed ratio reaches the target speed ratio and the half cycle of the vehicle longitudinal vibration at the target speed ratio are predicted, and the correction start time of the speed ratio is determined based on the prediction result. At this point, the gear ratio is corrected to the higher vehicle speed side to change the tendency of the drive torque to increase. [0005] However, during actual running, the accelerator pedal is usually operated during gear shifting, and the vehicle speed usually changes depending on road conditions.
In such a case, the above-described conventional apparatus merely changes the gear ratio to the high gear stage half a period before and after the end of the gear shift, and changes the accelerator opening and the accompanying gear ratio. No control is disclosed when the vehicle speed changes or the vehicle speed changes. Therefore, in the control by the above-described conventional device, the start of the longitudinal vibration suppression control is determined based on the target gear ratio determined at the beginning of the gear shift and the associated target rotation speed. When the running state of the vehicle such as the vehicle speed changes, the control for suppressing the longitudinal vibration becomes inappropriate, and the longitudinal vibration may not be sufficiently suppressed or the shift responsiveness may be deteriorated. For example, when the target rotation speed changes during a rapid shift, if the shift control is executed according to a schedule based on the previous target rotation speed, the shift control for the previous target rotation speed and the shift control for the new target rotation speed are performed. Continuously occur, the driving torque becomes a two-stage acceleration waveform, and there is a possibility that the riding comfort or drivability is deteriorated. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is desirable to appropriately control the longitudinal vibration of a vehicle accompanying a shift even if the state of the vehicle changes during a shift. It is an object of the present invention to provide a shift control device that can perform the shift control. SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a longitudinal vibration which is determined in advance based on a period of a longitudinal vibration of a vehicle which is expected to occur at the end of a shift. In a shift control device for a vehicle equipped with a continuously variable transmission that starts control for suppressing vehicle longitudinal vibration at a time before a shift end time only during a suppression period, a target rotational speed that changes according to a traveling state during a shift operation. Means for determining the required time until the target rotational speed is reached when the current shift speed is continued, and the determined required time is shorter than a predetermined judgment reference period shorter than the longitudinal vibration suppression period. And means for starting suppression control of the vehicle longitudinal vibration when it is detected that the required time is shorter than the determination reference period. It is assumed that. Therefore, according to the shift control device of the present invention, the control for suppressing the vehicle longitudinal vibration expected to occur at the end of the gear shift is performed by the shift ending for a predetermined longitudinal vibration suppression period based on the cycle of the longitudinal vibration. Started before the time. During the shift, a target rotation speed that changes according to the traveling state and a time required to reach the target rotation speed based on the shift speed at that time are obtained. That is, if the output demand amount such as the accelerator opening degree or the traveling state such as the vehicle speed changes during the gear shift, the target rotation speed changes accordingly.
Even during the shift, the target rotation speed and the time required to reach the target rotation speed are constantly updated. The required time updated in this manner is compared with a predetermined criterion period shorter than the longitudinal vibration suppression period, and it is detected that the updated required time is shorter than the criterion period. Then, the longitudinal vibration suppression control is started at that time. As a result, according to the present invention, even if the traveling state changes during gear shifting, and accordingly the target rotation speed and the time to reach the target rotation speed change, the longitudinal vibration suppression control is executed with good timing, The longitudinal vibration of the vehicle can be suitably prevented or reduced. Next, the present invention will be described with reference to specific examples. First, an example of a power transmission system of a vehicle to which the present invention is applied will be described. In FIG. 3, an output shaft 2 of a prime mover 1 is connected to a transmission 3. Here, the prime mover 1 includes various power sources that can be used for a vehicle, such as an internal combustion engine such as a gasoline engine or a diesel engine, or an electric motor such as a motor, or a device combining these internal combustion engines and an electric motor. In the following description, the prime mover 1
An example in which an engine is adopted will be described. The engine 1 is configured to be electrically controllable, and is provided with an electronic control unit (ECU) 4 mainly composed of a microcomputer for the control. The control device 4 is configured to control at least the output of the engine 1, and an output request signal such as an output shaft rotation speed Ne and an accelerator opening Acc is input as data for the control. This output request signal is a signal for increasing / decreasing the output of the engine 1, and is an accelerator pedal (not shown) operated by the driver.
In the case of the engine 1 provided with an electronic throttle valve in addition to the operation amount signal Acc of the above, an electronic throttle valve opening control signal, a cruise control system (not shown) for maintaining the vehicle speed at a set vehicle speed, and the like. Output request signal from the PC. The transmission 3 is for enabling the engine 1 to be kept rotating even when the vehicle is stopped. The transmission 3 transmits the torque by pressing the friction plates against each other. Various types of clutches, such as a general clutch, a fluid coupling (fluid coupling), a fluid type torque converter, a torque converter having a built-in lock-up clutch, an electromagnetic clutch, a powder clutch, and the like, can be employed. The transmission 3 is connected to a forward / reverse switching mechanism 5. This is provided because a continuously variable transmission 6, which will be described later, cannot invert and output the input.
The forward / reverse switching mechanism 5 includes, for example, a 3
A mechanism having one rotating element, wherein one of the rotating elements is connected to the transmission 3 to be an input element, and the other one is a fixed element that is selectively fixed,
The remaining one rotation element is an output element. By fixing the fixed element by a brake mechanism or the like, the output element rotates in the opposite direction with respect to the input element, and by releasing the fixed element and connecting any two rotating elements integrally. , As a whole, and the input is output as it is. The continuously variable transmission 6 connected to the forward / reverse switching mechanism 5 will be described. The point of the continuously variable transmission 6 is that the speed ratio of the input shaft 7 and the output shaft 8 is continuously adjusted. This is a mechanism for changing, specifically, an appropriate type of continuously variable transmission such as a belt type or a toroidal type. An electronic control unit (ECU) 9 for electrically controlling the gear ratio is provided. The electronic control unit 9 is connected to the electronic control unit 4 for the engine 1 so as to be able to perform data communication, and inputs necessary data such as a vehicle speed for controlling a gear ratio. The output shaft 8 of the continuously variable transmission 6 is connected to a final reduction gear (differential gear) 10.
The differential gear 10 distributes torque to the right and left wheels while allowing differential rotation of the wheels. In a vehicle having a power transmission system including the continuously variable transmission 6 described above, for example, when a shift is performed to increase the speed ratio in the continuously variable transmission 6, the torque applied to the power transmission system increases. In addition, an inertial force is generated due to the torsion and rotation change of the power transmission system, which may cause an overshoot (push up) of the torque at the end of the shift. In addition, longitudinal vibration of the vehicle may be caused accordingly. Therefore, the above control device according to the present invention
At the end of the shift, control is performed to suppress vehicle longitudinal vibration. This is, for example, control for reducing the shift speed from a point in time half a cycle before and after the predicted shift end point of the vehicle longitudinal vibration, or reducing the output torque of a power source such as an engine. The control device according to the present invention determines the start point of the vehicle longitudinal vibration suppression control as follows. FIG. 1 is a flowchart showing an example of a routine for judging the start timing of the longitudinal vibration suppression control. After performing initial processing such as reading of necessary data, a discrimination flag F during rapid shift control is set. It is determined whether or not it is set to "1" (step 1). Here, the rapid shift control refers to a vehicle in which a change in torque applied to the power transmission system is increased due to a large change width (change amount) of the gear ratio, and is expected to occur at the end of the shift. This is shift control in which control for suppressing longitudinal vibration is performed. The determination of the shift control with the longitudinal vibration suppression control at the shift end timing is performed by another routine (not shown) based on the change amount of the total torque acting on the power transmission system due to the shift. If a positive determination is made in step 1 because the so-called rapid shift control is being performed, the required time ta required to reach the target rotational speed is obtained (step 2). This is because the current target engine speed Net and the actual engine speed N
ta = (Net-Ne) /. DELTA.Ne based on e and the rate of change of the engine speed (i.e., shift speed) .DELTA.Ne at that time. The target engine speed Net
Can be determined based on the output demand and the vehicle speed for the power source such as the accelerator opening at that time.Specifically, a map using the accelerator opening and the vehicle speed as parameters is prepared in advance, and the map is prepared. Can be determined based on The routine shown in FIG. 1 is executed at predetermined short intervals. Each time, the target engine speed Net is obtained, and the required time ta to reach the target engine speed Net is calculated based on the target engine speed Net. In other words, the target engine speed Net and the required time to reach the target engine speed ta are constantly obtained, and these are updated even during shifting by changing running conditions such as accelerator opening and vehicle speed. Therefore, step 2 corresponds to a means for obtaining the target rotation speed and the time required to reach the target rotation speed in the present invention. Next, it is determined whether or not the required time ta is shorter than the criterion period To / 4 (step 3). Here, To is the cycle of the vehicle longitudinal vibration that is expected to occur at the time when the target rotational speed is reached, that is, at the end of the shift, so that the determination reference time in this specific example is 1/4 of the cycle. More specifically, the control for suppressing the longitudinal vibration of the vehicle is started at a time earlier than the shift end time by a predetermined period (for example, To / 2) based on the cycle of the longitudinal vibration. In this control, the point in time that is shorter than the execution period of the longitudinal vibration suppression control by the time when the target engine speed is reached when the shift is performed at the shift speed at the start of the shift is determined. Therefore, step 3 corresponds to a means for detecting that the required time is shorter than the reference time in the present invention. If a negative determination is made in step 3, the previous shift speed ΔNe is adopted as the target shift speed ΔNet (step 4). Step 3
If the result is affirmative, that is, if the current speed is maintained and the target engine speed Net is reached, and the time is reached by a quarter of the period To of the longitudinal vibration To, the sudden speed change control is performed. The middle determination flag F is set to "0", and the counter value is set to a predetermined value Cts (step 5). The counter value Cts is a predetermined value as a continuation time of the longitudinal vibration suppression control. For example, when the shift speed is suppressed to the immediately preceding half, the target engine speed Net
It is time to reach. Therefore, this counter value Cts
Can be a value determined in advance according to a target gear ratio, a target engine speed, a shift speed, a vehicle speed, and the like. That is, a map value can be adopted. Then, when a positive determination is made in step 3, the longitudinal vibration suppression control is started (step 6). This is executed, for example, by setting the front-rear vibration suppression shift speed as the target shift speed ΔNet, and the front-rear vibration suppression shift speed is, for example, the previous shift speed ΔN
The shift speed is 1/2 of e. Therefore, step 6 corresponds to a means for starting the control for suppressing the longitudinal vibration in the present invention. Returning after the execution of the control of step 6, the determination of step 1 is made again. If the flag F is already set to "0" in step 5, a negative determination is made. As a result, the routine proceeds to step 7, where it is determined whether the counter value is "0". Immediately after the start of the longitudinal vibration suppression control, the counter value is set to the value C set in step 5.
Since it is ts, a negative determination is made in step 7, and in this case, the process proceeds to step 8 and the counter value is reduced by "1". Then, the program proceeds to a step S6, wherein the shift speed is maintained at the shift speed for suppressing the longitudinal vibration. That is, the control for suppressing the longitudinal vibration is continued. After starting the longitudinal vibration suppression control, the counter value is decreased by "1" each time the routine shown in FIG. 1 is executed. As a result, when the counter value becomes "0", step 7 is executed. Is affirmatively determined. That is, the counter value Cts set in step 5 is determined based on the execution cycle time of the routine of FIG. 1, and when the value becomes “0”, the engine speed N
e reaches the target number of revolutions Net, and the shift with longitudinal vibration suppression control ends. Then, in this case, the routine proceeds to step 9, where normal shift control (for example, proportional integration (PI) feedback control) is executed. FIG. 2 is a time chart when the control shown in FIG. 1 is executed. For example, when an accelerator pedal (not shown) is depressed, a shift determination with Net1 as the target rotation speed is established, and the shift control is started at time t1. The shift speed in that case is ΔNe. During the shift, more precisely, if the accelerator pedal is further increased at time t2 before the start of the longitudinal vibration suppression control for the rapid shift with Net1 as the target rotation speed, the target rotation speed is updated to Net2. You. In step 2 described above, the required time to reach the target rotational speed ta is calculated based on the updated target rotational speed. That is, the target rotation speed required time ta is updated. The target rotation speed required time ta is equal to Net.
At a time t3 which is one-fourth of the period To of the longitudinal vibration expected to occur at the end of the rapid shift with the target rotational speed of 2 and reaches the target rotational speed, the shift speed becomes the longitudinal vibration suppressing shift speed ΔNe / Set to 2. By continuing this shift speed for half the period To of the longitudinal vibration To (until time t4), the engine speed Ne increases to the target speed Net2, and the shift ends. Therefore, the engine speed Ne changes as shown by the thick solid line in FIG. When the accelerator pedal is not further depressed, the speed at the start of the shift is maintained, and the period of the longitudinal vibration expected to occur at the end of the shift at the initial target rotational speed Net1 is 1/1. The front-rear vibration suppression control is executed at a point before the end of the shift by two, and the shift speed is halved. Therefore, the engine speed Ne in that case changes as shown by the broken line. As described above, in the control device according to the present invention, the target rotational speed and the time required to reach the target rotational speed are always obtained, and the time of reaching the target rotational speed is determined by the period of the longitudinal vibration. The point in time before 1/4 is detected, and the longitudinal vibration suppression control for halving the shift speed from that point is started. Therefore, in the device according to the present invention, even when the target rotational speed changes during the gear shift, it is possible to prevent a situation in which the shift control is performed a plurality of times, stepwise, etc. Smooth shifting can be performed. In addition, since the shift speed during shifting and the shifting speed for suppressing longitudinal vibration at the end of shifting are always updated to match the target rotational speed, shifting at the shifting speed for suppressing longitudinal vibration is completed. The actual rotational speed at the time when the target rotational speed coincides with the target rotational speed with high accuracy. As a result, both the target followability and the response are improved. In the above-described specific example, the control for suppressing the longitudinal vibration at the end of the shift is started at a time before the end of the shift by a half of the period of the longitudinal vibration, and accordingly, the shift is performed at the current speed. Although the control for suppressing the longitudinal vibration is started at a point in time that is 1/4 of the period of the longitudinal vibration with respect to the target rotational speed when the target rotation speed is reached, the present invention
The present invention is not limited to the above specific example, and the duration and the start time of the longitudinal vibration suppression control may be appropriately set as necessary. In short, in the present invention, the start of the longitudinal vibration suppression control is started. If the time point is an appropriate time interval shorter than the continuation time of the suppression control determined based on the cycle of the longitudinal vibration, and the time point is set immediately before the target rotation speed reaching time point when the shift is continued at the current shift speed, Good. In the above specific example, the shift speed is reduced by half as the longitudinal vibration suppression control. However, the longitudinal vibration suppression control according to the present invention controls not only the speed but also the output of a power source such as an engine. It may be one that lowers it. Further, in the case of a belt-type continuously variable transmission, the speed of change of the groove width in the input-side and output-side pulleys is controlled by hydraulic pressure or the like. Alternatively, the tilting speed of the power roller may be controlled by hydraulic pressure or the like. As described above, according to the present invention, when the shift is continued at the current shift speed, the time required to reach the target rotational speed is always obtained, and the value is calculated before and after the end of the shift. Since the longitudinal vibration suppression control is executed when the time becomes equal to or less than a judgment reference period set as a period shorter than the longitudinal vibration suppression period determined based on the vibration cycle, the target rotational speed may be changed during gear shifting. However, a smooth shift can be performed, and the actual speed at the end of the speed change after the longitudinal vibration suppression control and the target speed match with high accuracy, so that there is no stepwise change in the driving torque. In addition, it is possible to perform a shift control with good target following and response.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing an example of a control routine for suppressing longitudinal vibration by the device of the present invention. FIG. 2 is a time chart showing a change in engine speed when the control shown in FIG. 1 is executed. FIG. 3 is a block diagram schematically illustrating an example of a power transmission system to which the present invention can be applied. [Description of Signs] 1 ... prime mover, 4, 9 ... electronic control unit, 6 ... continuously variable transmission.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48 B60K 41 / 00-41/28 F02D 29/00-29/06 F02D 41/00-41/40

Claims (1)

(57) [Claim 1] The vehicle is moved back and forth at a time earlier than the shift end time by a predetermined longitudinal vibration suppression period based on a cycle of the vehicle longitudinal vibration expected to occur at the end of the shift. In a shift control device for a vehicle equipped with a continuously variable transmission that starts control to suppress vibration, the target rotation speed changes according to the traveling state and the target rotation speed when the current shift speed is continued during shifting. Means for calculating a time required to reach a number; means for detecting that the calculated required time is shorter than a predetermined judgment reference period shorter than the longitudinal vibration suppression period; and Means for starting the vehicle longitudinal vibration suppression control when it is detected that the time is shorter than the determination reference period. A shift control device for a vehicle having a continuously variable transmission.