JP2000283285A - Driving force control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of driving force control in a low speed region while the input/output shaft rotating speed and the speed change ratio are respectively detected asynchronously. SOLUTION: In a driving force control device for setting the target torque the of an engine according to the arithmetic results of a target driving force fTd and the speed change ratio R(k), the arithmetic result of the speed change ratio is corrected when at least one of the period Tin of a rotation synchronous signal of an input shaft and the period Tout of a rotation synchronous signal of an output shaft is larger than the arithmetic period Tr of a speed change ratio operating part 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a driving force control device used in a vehicle or the like, and more particularly to appropriately controlling a driving force characteristic of a vehicle according to a traveling environment.

[0002]

2. Description of the Related Art Conventionally, as a driving force control device used in a vehicle, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-242862, a slope resistance of a road surface is estimated during uphill traveling, and the slope resistance is determined according to the slope resistance. There is known a device which corrects a speed ratio by controlling the reduction in acceleration or vehicle speed due to an increase in gradient resistance.

In this method, an engine torque is estimated from a throttle opening and an engine speed based on a map or the like, and the output torque is obtained by multiplying the engine torque by a speed ratio of a transmission and a final reduction ratio. The gradient resistance is calculated by subtracting the acceleration resistance, the rolling resistance, and the air resistance from the vehicle speed, and control is performed so that the target engine torque according to the gradient resistance is obtained.

[0004]

When the above-described driving force control is performed by a discrete-value control device, for example, a digital computer, the transmission ratio of the transmission is calculated by the input shaft and the output shaft of the automatic transmission. The number of rotations is detected by measuring the time interval of a pulse signal output in accordance with the rotation angle by a rotation sensor or the like that detects a change in magnetism in accordance with the proximity of a gear provided on the shaft and the tooth tip. The gear ratio is determined from the ratio of the rotational speed detection values.

[0005] The pulse signal corresponding to the rotation angle is
The arithmetic processing for obtaining the gear ratio from the detected time interval while being detected in synchronization with the rotation is executed at a preset cycle.

However, when the conventional example is controlled by a discrete value system, the detection of the number of rotations is performed in synchronization with the rotation of the input shaft and the output shaft, and the calculation process of the gear ratio is performed at predetermined time intervals. In the low vehicle speed region including the stop state, the interval between the pulses synchronized with the rotation of the input / output shaft is longer than the calculation period of the gear ratio, so that the detection accuracy of the input shaft rotation speed and the output shaft rotation speed of the transmission is improved. And the accuracy of the gear ratio calculated as the ratio of the output shaft rotation speed to the input shaft rotation speed decreases, the accuracy of the target engine torque also deteriorates.
There is a problem that the control accuracy of the driving force is reduced.

That is, when the vehicle is accelerated from a low vehicle speed range by starting or the like, the input shaft rotation speed and the output shaft rotation speed are, as shown in FIG. 12, a pulse generated by a rotation sensor of the input shaft connected to the engine side. The pulses generated by the rotation sensor of the output shaft connected to the drive shaft have different rotation speeds, so that the generation of the pulses is not synchronized. Further, the cycle for calculating the gear ratio is Tr in the figure, and the generation of the pulses is performed. And are running asynchronously.

In the low vehicle speed range where the vehicle starts moving from a stopped state, the period of the pulse from the rotation sensor of the output shaft is very long.
At time t2, the output shaft rotation speed becomes Vo1 based on the time interval Tout1. In addition,
If the pulse is not updated for a certain period of time or more, it is determined that the vehicle is in a stopped state.

On the other hand, the period of the pulse from the input shaft rotation sensor connected to the engine is shorter than that of the output shaft.
At times t1 and t3, the input shaft rotation speed is Vi1 at time t3 based on this time interval Tin1.

When the gear ratio is calculated at time t4, the gear ratio R (k) = Vi1 / Vo1.

Further, when a pulse is detected from the input shaft rotation sensor at time t5, the time interval Tin between time 3 and t5
2, the input shaft speed is updated to Vi2 at time t5.

Immediately after this, when the gear ratio is calculated at time t6, since the input / output shaft rotation speed updated immediately before is used at this time, R (k) = Vi2 / Vo1. As indicated by the one-dot chain line in the figure, since the pulse from the sensor is not detected even though the actual output shaft rotation speed is increasing, the gear ratio is calculated at the rotation speed Vo1 at time t2. As a result, the detected gear ratio includes a large error, and the accuracy is reduced.

Even when a continuously variable transmission is used as the transmission, a predetermined maximum Lo is set at low vehicle speeds such as when starting or immediately before stopping.
w is set to the gear ratio or the like. However, as shown in FIG. 13, as described above, at low vehicle speed, the pulse cycle of the rotation sensor of the output shaft and the input shaft is longer than the calculation cycle of the gear ratio. The calculation result of the gear ratio greatly fluctuates with respect to the actual gear ratio, and when the driving force control as in the above-described conventional example is performed based on this gear ratio, the control accuracy deteriorates and the engine torque fluctuates. There is a problem that drivability is reduced.

On the other hand, if the input / output shaft rotation speed increases and the cycle of each pulse becomes shorter than the calculation cycle, the calculation result of the gear ratio becomes equal to the actually set gear ratio.
When the vehicle speed is equal to or higher than a predetermined speed, the accuracy of the driving force control can be secured. Therefore, the deterioration of the driving force control accuracy due to the decrease in the calculation accuracy of the gear ratio appears at the time of starting or stopping.

To solve such a problem, for example, in Japanese Patent Application Laid-Open No. Hei 10-201274 proposed by the present applicant,
Although a calculation cycle of the rotation speed is set longer than a pulse cycle of the rotation synchronization to improve the calculation accuracy, in this case, the calculation cycle of the gear ratio cannot be made constant,
At an extremely low vehicle speed, that is, in an extremely low rotation speed region, the calculation cycle of the gear ratio becomes longer, and as a result, the calculation cycle of the target engine torque becomes longer, resulting in a problem that the responsiveness is reduced.

Further, as disclosed in Japanese Patent Application Laid-Open No. 5-262159, when the driving force is controlled in accordance with the vehicle speed obtained from the output shaft rotation speed, the operation cycle of the output shaft rotation speed becomes longer in a low vehicle speed range. As a result, the detection accuracy of the vehicle speed is reduced, so that in a low vehicle speed range, a vehicle speed for calculating a target value, which substitutes a fixed value, is also known.

However, when the above-described driving force control is performed according to this conventional example, an error occurs in the target value of the driving force control according to the substitute fixed value when the vehicle speed increases from 0, for example, at the time of starting. There was a problem that it reduced.

Further, it is conceivable to increase the number of pulses generated per one rotation of the input shaft and the output shaft in order to accurately detect the rotation speed of the input and output shafts in the low vehicle speed range. In this case, the pulse period becomes extremely short, and the cost of a digital computer employed to detect the pulse period with high accuracy increases.

The present invention has been made in view of the above problems, and an object of the present invention is to improve the accuracy of driving force control in a low vehicle speed range while asynchronously detecting the input / output shaft speed and the gear ratio. With the goal.

[0020]

According to a first aspect of the present invention, there is provided a target driving force setting means for setting a target driving force based on a driving state of a vehicle, and a method for controlling a period of a signal synchronized with a rotation of an input shaft of an automatic transmission. Input shaft rotation speed detecting means for detecting the input shaft rotation speed based on the output shaft rotation speed detecting device for detecting the output shaft rotation speed based on the cycle of a signal synchronized with the rotation of the output shaft of the automatic transmission; Speed ratio calculating means for calculating the speed ratio of the automatic transmission from the input shaft speed and the output shaft speed at a predetermined calculation cycle; and a target torque of the engine based on the calculation result of the target driving force and the speed ratio. And a driving force control device for controlling the engine so as to achieve the target engine torque, wherein the speed ratio calculating means includes a rotation synchronization signal for the input shaft. Lap of When, among the period of the rotation synchronizing signal of the output shaft, when at least one of the period is greater than the calculation cycle of the speed ratio calculating means is provided with a gear ratio correcting means for correcting the calculation result of the transmission ratio.

According to a second aspect of the present invention, in the first aspect, the speed ratio correction means includes at least one of a cycle of a rotation synchronization signal of an input shaft and a cycle of a rotation synchronization signal of an output shaft. Is larger than the calculation cycle of the gear ratio calculation means, the maximum gear ratio of the automatic transmission is set as the calculation result.

In a third aspect based on the first aspect, the speed ratio correction means includes at least one of a cycle of a rotation synchronization signal of an input shaft and a cycle of a rotation synchronization signal of an output shaft. Is larger than the calculation cycle of the speed ratio calculating means, the previous calculation result is set as the current speed ratio.

The fourth invention is characterized in that the second or the third is
In the invention, the speed ratio correction means may include a speed ratio calculation means of a period of the rotation synchronization signal of the input shaft and a period of the rotation synchronization signal of the output shaft, at or near the maximum speed ratio of the automatic transmission. Is larger than the calculation cycle of
This is compared with the calculation cycle.

According to a fifth aspect of the present invention, there is provided a target driving force setting means for setting a target driving force based on a driving state of a vehicle, and an input shaft based on a period of a signal synchronized with a rotation of an input shaft of the automatic transmission. An input shaft rotation number detecting means for detecting a rotation number; an output shaft rotation number detecting means for detecting an output shaft rotation number based on a cycle of a signal synchronized with the rotation of the output shaft of the automatic transmission; Speed ratio calculating means for calculating the speed ratio of the automatic transmission at a predetermined calculation cycle from the output shaft speed and a target for setting the target torque of the engine based on the result of the calculation of the target driving force and the speed ratio. In a driving force control apparatus for a vehicle, comprising: an engine torque setting means; and a driving force control means for controlling an engine so as to attain a target engine torque. Performance A speed ratio correction that corrects the speed ratio calculation result when at least one of the ratio of the period ratio, the period of the rotation synchronization signal of the output shaft, and the ratio of the calculation period is smaller than a preset value; Means are provided.

In a sixth aspect based on the fifth aspect, the speed ratio correction means includes a ratio of a period of the rotation synchronization signal of the input shaft to the operation period, and a period of the rotation synchronization signal of the output shaft. If at least one of the ratios of the calculation periods is smaller than a preset value, the maximum gear ratio of the automatic transmission is set as the calculation result.

In a seventh aspect based on the fifth aspect, the speed ratio correction means includes a ratio of a period of the rotation synchronization signal of the input shaft to a ratio of the operation period, and a period of the rotation synchronization signal of the output shaft. When at least one of the ratios of the calculation periods is smaller than a preset value, the previous calculation result is set as the current gear ratio.

According to an eighth aspect of the present invention, there is provided a target driving force setting means for setting a target driving force based on a driving state of a vehicle, and an input shaft based on a period of a signal synchronized with a rotation of an input shaft of the automatic transmission. An input shaft rotation number detecting means for detecting a rotation number; an output shaft rotation number detecting means for detecting an output shaft rotation number based on a cycle of a signal synchronized with the rotation of the output shaft of the automatic transmission; Speed ratio calculating means for calculating the speed ratio of the automatic transmission at a predetermined calculation cycle from the output shaft speed and a target for setting the target torque of the engine based on the result of the calculation of the target driving force and the speed ratio. In a driving force control device for a vehicle, comprising an engine torque setting means and a driving force control means for controlling an engine so as to attain a target engine torque, the speed ratio calculating means comprises: Times Within a few, it is smaller than the minimum rotation speed, at least one of the preset is provided with a gear ratio correcting means for correcting the calculation result of the transmission ratio.

In a ninth aspect based on the eighth aspect, the speed ratio correction means is configured such that at least one of the detected input shaft speed and output shaft speed is higher than a preset minimum speed. If is also smaller, the maximum gear ratio of the automatic transmission is set as the calculation result.

In a tenth aspect based on the eighth aspect, the speed ratio correction means is configured such that at least one of the detected input shaft speed and output shaft speed is higher than a preset minimum speed. If is also smaller, the previous calculation result is set as the current gear ratio.

An eleventh aspect of the present invention provides a target driving force setting means for setting a target driving force based on a driving state of a vehicle,
An input shaft rotation speed detecting means for detecting an input shaft rotation speed based on a cycle of a pulse signal synchronized with rotation of an input shaft of the automatic transmission; and Output shaft rotation speed detection means for detecting the output shaft rotation speed by using the input shaft rotation speed and the output shaft rotation speed to calculate the gear ratio of the automatic transmission at a predetermined calculation cycle; A driving force of a vehicle including target engine torque setting means for setting a target torque of an engine based on a calculation result of a target driving force and a gear ratio, and driving force control means for controlling an engine to achieve the target engine torque. In the control device, the speed ratio calculating means may determine whether the number of pulse signals detected by the input shaft speed detecting means and the output shaft speed detecting means immediately after the vehicle starts exceeds a predetermined number. Providing a gear ratio correcting means for correcting the calculation result of the transmission ratio.

In a twelfth aspect based on the eleventh aspect, the speed ratio correction means is arranged such that the number of pulse signals is
Until the value reaches at least 2, a preset value is set as the current gear ratio.

In a thirteenth aspect based on the eleventh aspect, the transmission ratio correction means is arranged such that the period of the pulse signal detected by the input shaft speed detecting means and the output shaft speed detecting means is set in advance. A start detecting means for detecting the start of the vehicle when the period becomes equal to or less than the cycle is provided.

In a fourteenth aspect based on the twelfth aspect, the transmission ratio correcting means is configured to determine that the number of pulse signals detected by the force shaft speed detecting means and the output shaft speed detecting means is at least two. Until the above, the maximum gear ratio of the automatic transmission is set as the current gear ratio.

[0034]

According to the first aspect of the present invention, a target driving force is set based on a driving state of a vehicle, and a driving force is controlled by obtaining a target engine torque from a gear ratio of the automatic transmission and the target driving force. In the calculation of the gear ratio, the rotational speeds of the input and output shafts of the automatic transmission are determined in synchronization with each other, and the gear ratio is calculated from the ratio of these rotational speeds.

When the gear ratio is calculated at a predetermined calculation cycle, the period of the rotation synchronization signal of the input shaft and the period of the rotation synchronization signal of the output shaft are smaller than the calculation period at a low vehicle speed such as when starting or immediately before stopping. At low vehicle speeds, at least one of the cycle of the rotation synchronization signal of the input shaft or the cycle of the rotation synchronization signal of the output shaft becomes longer than the calculation cycle of the gear ratio calculation means, the calculation result of the gear ratio is corrected. As a result, it is possible to reliably prevent an error or change in the speed ratio in a low vehicle speed range as in the above-described conventional example, and to perform driving force control based on the corrected speed ratio at a low vehicle speed such as when starting or stopping. This makes it possible to improve the drivability of the vehicle while performing the detection of the rotational speed of the input / output shaft and the calculation of the gear ratio asynchronously.

In a second aspect of the present invention, at low vehicle speeds, at least one of the cycle of the rotation synchronization signal of the input shaft and the cycle of the rotation synchronization signal of the output shaft is larger than the calculation cycle of the speed ratio calculation means. Since the maximum transmission ratio of the automatic transmission is used as the result of calculating the transmission ratio, the transmission ratio is fixed to the maximum value, and it is possible to reliably prevent the occurrence of errors and fluctuations in the transmission ratio as in the conventional example. In the low vehicle speed range, the actual gear ratio is also set to the maximum value side. Therefore, even if the maximum gear ratio, which is a fixed value, is set in the calculation result, it is possible to suppress the occurrence of an error, and the drive based on this gear ratio Force control can be performed with high accuracy even in low vehicle speed ranges such as when starting and stopping, and the drivability of the vehicle can be detected while asynchronously detecting the rotation speed of the input and output shafts and calculating the gear ratio. Can be improved.

In a third aspect of the present invention, at low vehicle speeds, at least one of the period of the rotation synchronization signal of the input shaft and the period of the rotation synchronization signal of the output shaft is larger than the calculation period of the speed ratio calculation means. By setting the previous calculation result as the current gear ratio, when the vehicle speed decreases due to deceleration or the like and enters a low vehicle speed region where an error occurs in the calculation of the gear ratio, the gear ratio is held at the immediately preceding value. As a result, it is possible to suppress the error of the gear ratio and to perform the driving force control with high accuracy even in the low vehicle speed range at the time of starting or stopping, and in addition to using the ABS (anti-lock brake system) for the driving force control. When combined, when the speed ratio of the automatic transmission is changed to a small value (Hi side) during the operation of the ABS and the operability of the ABS is improved, the ABS is activated by braking to enter a low vehicle speed range and the rotation speed is reduced. Sync signal When the period is longer than the calculation cycle,
By maintaining the previous gear ratio, an excessive change in the gear ratio can be suppressed, a sudden change in engine torque can be prevented, and the accuracy of driving force control can be ensured.

According to the fourth aspect of the invention, the calculation load can be reduced by comparing the period of the rotation synchronizing signal which is longer than the calculation period at or near the maximum speed ratio.

According to a fifth aspect of the present invention, the ratio of the period of the rotation synchronization signal of the input shaft to the operation period and the ratio of the period of the rotation synchronization signal of the output shaft to the operation period are determined. Is smaller than a preset value, the calculation result of the gear ratio is corrected, so that an error or fluctuation of the gear ratio in a low vehicle speed range as in the conventional example can be reliably prevented, and the correction is performed. It is possible to perform driving force control based on the changed gear ratio with high accuracy even in a low vehicle speed range such as when starting or stopping, and the detection of the rotational speed of the input / output shaft and the calculation of the gear ratio are performed asynchronously. It is possible to improve the drivability of the vehicle while performing.

According to a sixth aspect of the present invention, at least one of a ratio of the period of the rotation synchronization signal of the input shaft to the operation period and a ratio of the period of the rotation synchronization signal of the output shaft to the operation period is set in advance. When the value is smaller than the value, the maximum speed ratio of the automatic transmission is set as the calculation result, so that the speed ratio is fixed at the maximum value, and errors and fluctuations of the speed ratio as in the conventional example are surely prevented. Can be prevented.

According to a seventh aspect of the present invention, at least one of a ratio between the period of the rotation synchronization signal of the input shaft and the operation period and a ratio between the period of the rotation synchronization signal of the output shaft and the operation period is set in advance. If the speed ratio is smaller than the value, the previous calculation result is set as the current speed ratio, and when the vehicle speed falls due to deceleration or the like and enters a low vehicle speed region where an error occurs in the calculation of the speed ratio, the speed ratio becomes Since the value is maintained at the immediately preceding value, it is possible to suppress an error in the gear ratio and secure the accuracy of the driving force control.

According to an eighth aspect of the present invention, when at least one of the input shaft rotation speed and the output shaft rotation speed is smaller than a preset minimum rotation speed, the calculation result of the gear ratio is corrected. As in the conventional example described above, it is possible to reliably prevent an error or change in the speed ratio in a low vehicle speed range, and to perform driving force control based on the corrected speed ratio with high accuracy even in a low vehicle speed range such as when starting or stopping. This makes it possible to improve the drivability of the vehicle while performing the detection of the rotational speed of the input / output shaft and the calculation of the gear ratio asynchronously.

According to a ninth aspect, when at least one of the input shaft rotation speed and the output shaft rotation speed is smaller than a preset minimum rotation speed, the maximum gear ratio of the automatic transmission is calculated as a calculation result. By setting, the speed ratio is fixed to the maximum value in a low vehicle speed range, and errors and fluctuations of the speed ratio as in the conventional example can be reliably prevented.

According to a tenth aspect, when at least one of the input shaft rotation speed and the output shaft rotation speed is smaller than a preset minimum rotation speed, the previous calculation result is set as the current gear ratio. As a result, when the vehicle speed decreases due to deceleration or the like and enters a low vehicle speed region where an error occurs in the calculation of the gear ratio,
Since the speed ratio is held at the immediately preceding value, it is possible to suppress an error in the speed ratio and secure the accuracy of the driving force control.

Further, according to the eleventh invention, the speed ratio is maintained until the number of pulse signals detected by the input shaft revolution detecting means and the output shaft revolution detecting means immediately after the vehicle starts exceeds a preset number. Since the calculation result is corrected, when the vehicle speed starts near 0, among the pulses detected by the input / output shaft rotation speed detection means, the pulse immediately after the start is ignored, and the speed ratio is changed from a predetermined number or more pulses. By starting the calculation, the calculation accuracy can be improved, and the driving force control can be performed with high accuracy from a low vehicle speed range.

Further, in the twelfth invention, a predetermined value is set as the current gear ratio until the number of pulse signals becomes at least two, so that two pulses immediately after the start are ignored. By fixing the gear ratio during this time to a preset value, fluctuations of the gear ratio in the low vehicle speed range are prevented, and the accuracy of the driving force control is ensured. The driving force can be controlled with high accuracy from the range.

According to a thirteenth aspect of the present invention, the start of the vehicle is detected when the cycle of the pulse signal detected by the input shaft speed detecting means and the output shaft speed detecting means becomes equal to or less than a preset period. Thus, the pulse at the time of starting can be surely grasped.

According to a fourteenth aspect, the speed ratio is fixed at the maximum speed ratio until the number of pulse signals detected by the input shaft speed detecting means and the output shaft speed detecting means becomes at least two or more. This makes it possible to correct the calculation result of the gear ratio, which fluctuates greatly in the early stage of starting, and to secure the accuracy of the driving force control.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example in which the present invention is applied to a vehicle provided with a controller 1 for controlling the output of an engine 3 and the speed ratio of an automatic transmission 2 so as to obtain an optimum driving force according to the running state. Is shown.

The automatic transmission 2 connected to the engine 3 via the torque converter T / C is provided with gears 23 and 24 on an input shaft 21 and an output shaft 22, respectively. An input shaft rotation sensor 11 and an output shaft rotation sensor 12, each of which is constituted by a Hall element or the like and generates a pulse at each predetermined angle, are provided, and the outputs of these sensors are sent to the controller 1.

Although an example in which a toroidal type continuously variable transmission is used as the automatic transmission 2 is shown, a V-belt type or the like may be used.

The controller 1 is mainly composed of a digital computer which performs a discrete value system control. In order to detect an operating state and a running state, an accelerator depression amount APO (or throttle opening amount) from an accelerator pedal opening sensor 13 is detected. Degree TVO), the engine speed Ne from the crank angle sensor 15, and the gear ratio R detected according to the pulses from the input shaft rotation sensor 11 and the output shaft rotation sensor 12.
(K) Based on the vehicle speed VSP and the like from the vehicle speed sensor 14, control the fuel injection amount of the engine 3, the ignition timing, and control the transmission ratio of the automatic transmission 2 to control the driving force of the vehicle.

An example of the driving force control performed by the controller 1 is as shown in FIG.
And a vehicle speed VSP based on the vehicle speed VSP from the accelerator pedal opening amount sensor 13 and the target driving force tTd calculated from a map set in advance. The target driving force tTd and the vehicle speed VSP A target gear ratio calculating section 32 for calculating a target gear ratio tR (k) from a set map in advance in accordance with the above-mentioned conditions, and an automatic gear shift in response to pulses (rotation synchronization signals) from the input shaft rotation sensor 11 and the output shaft rotation sensor 12. A gear ratio detection unit 40 for detecting a gear ratio R (k) set for the machine 2 and a target drive force tTd for the gear ratio R
(K) a target engine torque calculating unit 33 that outputs the target engine torque tTe, an engine control unit 34 that controls the fuel injection amount and the ignition timing based on the target engine torque tTe, tR
The shift control unit 35 controls the shift mechanism of the automatic transmission 2 according to (k).

The gear ratio detecting unit 40 includes pulse cycle counters 41 and 42 for detecting the update cycles Tin and Tout of the pulses detected by the input shaft rotation sensor 11 and the output shaft rotation sensor 12, respectively. The input shaft rotation speed Nin and the output shaft rotation speed Nout are calculated from the number of teeth of the gears 23 and 24, and the ratio of these is = Nout / N.
A speed ratio calculation unit 43 that calculates in as an actual speed ratio R (k) is provided.

Here, an example of the gear ratio calculation performed by the gear ratio detector 40 of FIG. 2 is shown in the flowchart of FIG. Note that this flowchart is executed for each preset operation cycle Tr. For example, the operation cycle Tr =
It is set to 10 msec.

First, at step S1, the pulse cycle counters 41 and 42 update the pulse update cycles Tin and To from the input shaft rotation sensor 11 and the output shaft rotation sensor 12, respectively.
Read ut.

Then, in step S2, a calculation cycle Tr of the gear ratio, which is a fixed value, and an update cycle Tin of each pulse,
Compared with Tout, if both of these update periods are shorter than the operation period Tr, the speed ratio is calculated in step S3 and subsequent steps. If one of the update periods is longer than the operation period Tr, step S5 is executed. To the actual speed ratio R
(K) the maximum gear ratio Rmax (maximum Low
Gear ratio).

On the other hand, in step S3, the input shaft rotation speed Nin is calculated from the pulse update period Tout of the input shaft rotation sensor 11 and the known number of teeth of the gear 23 (ie, the number of generated pulses per rotation of the input shaft). The output shaft rotation speed Nout is calculated from the pulse update period Tout of the output shaft rotation sensor 12 and the known number of teeth of the gear 24 (that is, the number of generated pulses per rotation of the output shaft).

In step S4, the ratio of the input shaft rotation speed Nin to the output shaft rotation speed Nout = Nin / Nout
Is calculated as the actual speed ratio R (k).

Therefore, at low vehicle speeds where the pulse update cycle Tout of the output shaft rotation sensor 12 or the pulse update cycle Tin of the input shaft rotation sensor 11 is longer than the gear ratio calculation cycle Tr, the gear ratio R (k) Is the maximum value Rmax
, The error and fluctuation of the speed ratio as in the prior art can be reliably prevented, and the actual speed ratio is set to the maximum value (the lowest Low speed ratio) in the low vehicle speed range. Even if the value Rmax is set to the speed ratio R (k), it is possible to suppress the occurrence of an error, and the driving force control based on the speed ratio R (k) is highly accurate from a low vehicle speed range such as when starting or stopping. This makes it possible to improve the drivability of the vehicle while performing the detection of the rotational speed of the input / output shaft and the calculation of the gear ratio asynchronously.

Then, the vehicle speed VSP increases and the update period Tin of the input shaft rotation sensor 11 and the output shaft rotation sensor 12
When the update period Tout of the second embodiment is less than or equal to the operation period Tr of the speed ratio, the speed ratio can be calculated based on the actual rotational speed detection value without causing the error of the speed ratio as in the above-described conventional example. Driving force control can be performed with high accuracy in all regions from the vehicle speed region to the high vehicle speed region.

FIG. 4 shows the second embodiment. In the flowchart of FIG. 3 shown in the first embodiment, the setting of the maximum speed ratio Rmax performed in step S5 is changed to the previous speed ratio R (k−k). Step 1 is changed to step S5A, and the other configuration is the same as that of the first embodiment.

In step S5A of FIG. 4, if both the update periods Tin and Tout of the input / output shaft rotation sensors 11 and 12 become longer than the calculation period Tr, an error occurs in the calculation accuracy of the speed ratio. (K-1) is maintained so that when the vehicle speed VSP becomes a low vehicle speed and enters an area where an error occurs in the calculation of the gear ratio, the gear ratio becomes the previous gear ratio R (k-1). Therefore, errors and fluctuations in the gear ratio as in the conventional example can be reliably prevented.

That is, when the continuously variable transmission is employed as the automatic transmission 2, when the vehicle speed VSP decreases and the vehicle enters a low vehicle speed range where an error occurs in the calculation of the gear ratio, the target gear ratio tR
(K) shifts to the maximum value side (Low side), and by maintaining the previous speed ratio R (k-1) in step S5A, the error of the speed ratio is suppressed, and the low speed at the time of starting or stopping is suppressed. Driving force control can be performed with high accuracy from the vehicle speed range.

Further, the driving force control and the ABS (anti-lock brake system) are combined to change the speed ratio of the automatic transmission 2 to a small value (Hi side) during the operation of the ABS, thereby improving the operability of the ABS. In this case, when the ABS is activated by braking to enter a low vehicle speed range and the pulse update periods Tin and Tout become longer than the calculation period Tr,
Since the previous gear ratio R (k-1) is maintained, the gear ratio does not fluctuate excessively, so that a sudden change in engine torque can be prevented, and the accuracy of driving force control can be ensured.

FIG. 5 shows a third embodiment. In the flowchart of FIG. 3 shown in the first embodiment, the determination made in step S2 is determined by the input / output shaft rotation sensors 11 and 12.
Are performed by the ratio of the detected pulse update periods Tin and Tout to the operation period Tr, and the other configuration is the same as that of the first embodiment.

In step S2A of FIG. 5, the value obtained by dividing the speed ratio calculation period Tr by the update period Tin of the input shaft rotation sensor 11 and the speed ratio calculation period Tr are used as the output shaft rotation sensor 1
If the values divided by the update cycle Tout of 2 are both equal to or greater than the preset value K, the calculation accuracy of the gear ratio can be ensured.
The calculation of (k) is performed.

On the other hand, the value obtained by dividing the speed ratio calculation cycle Tr by the update cycle Tin of the input shaft rotation sensor 11 and the value obtained by dividing the speed ratio calculation cycle Tr by the update cycle Tout of the output shaft rotation sensor 12 are used.
If any one of the values divided by the above is smaller than the preset value K, it is determined that the low vehicle speed range causes an error in the calculation result of the gear ratio because the pulse update periods Tin and Tout become longer. Then, the process proceeds to step S5, where the actual speed ratio R
(K) is fixed to the maximum value Rmax.

In this case, the value K to be compared is, for example, K = 2
Since the calculation accuracy is set to a value that can ensure the calculation accuracy, the gear ratio can be calculated using the actually detected period as much as possible until the period ratio, which is the lower limit of the calculation accuracy, becomes K. it can.

FIG. 6 shows the fourth embodiment. In the flowchart of FIG. 5 shown in the third embodiment, the setting of the maximum speed ratio Rmax performed in step S5 is the same as in the second embodiment. The step is changed to step S5A for setting the previous speed ratio R (k-1), and the other configuration is the same as that of the third embodiment.

In this case, as long as the period ratio, which is the lower limit of the calculation accuracy, is equal to or greater than the preset value K, the gear ratio can be calculated using the actually detected period as much as possible. By maintaining the previous gear ratio R (k-1), A
Even when the BS is in operation, excessive fluctuation of the target engine torque can be prevented, and the accuracy of the driving force control can be ensured.

FIG. 7 shows a fifth embodiment. In the flowchart of FIG. 3 shown in the first embodiment, the determination made in step S2 is based on the update cycle Tout of the pulse detected by the output shaft rotation sensor 12. And the operation cycle Tr. The other configuration is the same as that of the first embodiment.

In step S2B of FIG. 7, if the update cycle Tout of the output shaft rotation sensor 12 is longer than the speed ratio calculation cycle Tr, it is determined that the vehicle is in a low vehicle speed range where an error occurs in the calculation result of the speed ratio R (k). After the determination, the process proceeds to step S5 to fix the actual speed ratio R (k) to the maximum value Rmax.

In this case, since the update cycle Tin of the input shaft rotation sensor 11 is on the engine side, the speed ratio R (k) becomes large (Low side) in a low vehicle speed range, compared with the update cycle Tout on the output shaft side. short. For this reason, the above step S2B
, The update period To of the output shaft rotation sensor 12 which greatly affects the calculation accuracy of the gear ratio.
By performing the comparison using only ut, the calculation load is reduced.

Here, the maximum speed ratio (lowest speed ratio) set for the automatic transmission 2 is 2.3, the number of pulses per rotation of the input shaft is 25, and the number of pulses per rotation of the output shaft is 3
Assuming that the input shaft rotation speed is ω _in [rad / sec] and the output shaft rotation speed is ω _out [rad / sec], the update periods Tin and Tout of the input / output shaft rotation sensors 11 and 12 are respectively:

[0077]

(Equation 1) Since Tout> Tin, the calculation accuracy can be ensured even if the update cycle Tin detected by the input shaft rotation sensor 11 is excluded from the comparison target.

However, the number of pulses per rotation of the input shaft and the output shaft can be set arbitrarily, and the input / output shaft rotation sensor 11 and the input / output shaft rotation sensor 11 are set so that Tin> Tout at or near the maximum speed ratio. 12 gears 23, 24
When the number of teeth is set, the comparison in step S2B may be performed with the update period Tin of the input shaft rotation sensor 11 whose period becomes longer near the maximum speed ratio.

The reason why the speed ratio is set near the maximum speed ratio is that the speed ratio of the automatic transmission 2 is not always at the maximum speed ratio when the vehicle is stopped. For example, a belt type or the like is adopted as the automatic transmission 2. This is because, in such a case, the vehicle may be stopped at a speed ratio (Hi side) smaller than the maximum speed ratio at the time of sudden deceleration or the like.

FIG. 8 shows a sixth embodiment. In the flowchart of FIG. 7 shown in the fifth embodiment, the setting of the maximum speed ratio Rmax performed in step S5 is the same as in the second embodiment. The step is changed to step S5A for setting the previous speed ratio R (k-1), and the other configuration is the same as that of the fifth embodiment.

In this case, the region where the calculation accuracy of the gear ratio is reduced is determined only by the update cycle Tout of the output shaft rotation sensor 12 to reduce the calculation load, and the gear ratio R (k)
In a region where the calculation accuracy of the gear ratio decreases, the previous gear ratio R (k−
By maintaining 1), it is possible to prevent the target engine torque from excessively fluctuating even when the ABS is operating, and to ensure the accuracy of the driving force control.

FIG. 9 shows a seventh embodiment, which is executed every predetermined time Tr = 10 msec in the same manner as described above.

In step S10, the pulse cycle counters 41 and 42 update the pulse update cycles Tin and Tout from the input shaft rotation sensor 11 and the output shaft rotation sensor 12, respectively.
Read.

In step S11, the input shaft rotation sensor 1
The input shaft rotation speed Nin is calculated from the pulse update period Tout of 1 and the known number of teeth of the gear 23 (that is, the number of generated pulses per one rotation of the input shaft), and the pulse update period Tout of the output shaft rotation sensor 12 is calculated. The output shaft rotation speed Nout is calculated from the known number of teeth of the gear 24 (that is, the number of pulses generated per rotation of the output shaft).

Next, in step S12, the minimum output shaft speed Nmi at which the gear ratio, which is a preset value, can be calculated.
n is compared with the calculated output shaft rotation speed Nout, and the output shaft rotation speed Nout is set to the minimum output shaft rotation speed Nmin.
If it is the above, it is determined that it is an area where the calculation accuracy of the speed ratio can be ensured, and the process proceeds to step S13 to calculate the speed ratio R (k) from the ratio of the detected values Nin and Nout of the input / output shaft rotation speed. On the other hand, if the output shaft rotation speed Nout is less than the minimum output shaft rotation speed Nmin, it is determined that the speed ratio calculation accuracy is low in a low vehicle speed range, and the process proceeds to step S14. A preset maximum gear ratio Rmax (maximum L
ow gear ratio).

The minimum output shaft rotation speed Nmin is a minimum value that can secure the calculation accuracy of the gear ratio, and is, for example, Nmin.
= 20 [rad / sec], and the update cycle Tout is a value exceeding the calculation cycle Tr.

Therefore, at low vehicle speeds where the output shaft rotation speed Nout is less than the minimum output shaft rotation speed Nmin, the gear ratio R (k) is fixed at the maximum value Rmax. And fluctuations can be reliably prevented, and
Actual speed ratio is also maximum value (lowest speed ratio) in low vehicle speed range
, The fixed value Rmax is changed to the gear ratio R
Even if it is set to (k), the occurrence of an error can be suppressed, and the driving force control based on this speed ratio R (k) can be performed with high accuracy from a low vehicle speed range such as when starting or stopping. Thus, the drivability of the vehicle can be improved while the detection of the rotation speed of the input / output shaft and the calculation of the gear ratio are performed asynchronously.

In step S12, the output shaft rotation speed Nout is compared with the minimum rotation speed Nmin. However, the speed ratio is obtained from each of the rotation speeds obtained in step S11, and this speed ratio is compared with a preset value. You may compare.

FIG. 10 shows an eighth embodiment.
In the flowchart of FIG. 9 shown in the embodiment, the setting of the gear ratio R (k) performed in step S14 is the same as the second gear ratio.
Similar to the seventh embodiment, the process is changed to step S14A for setting the previous gear ratio R (k-1), and the other configuration is the same as that of the seventh embodiment.

In this case, the region where the calculation accuracy of the speed ratio is reduced is defined by the minimum output shaft speed Nmin and the output shaft speed Nou.
In the region where the calculation accuracy of the gear ratio R (k) is reduced, the previous gear ratio R (k-1) is maintained, so that the target engine torque of the target engine torque is maintained even when the ABS is operating. Excessive fluctuation can be prevented, and the accuracy of driving force control can be ensured.

FIG. 11 shows a ninth embodiment, in which the first
The pulse period counters 41 and 42 shown in FIG.
It is determined that the vehicle is stopped from the overflow of the vehicle, and two rotation sensors 11 and
12 counts the number of times the pulse signal is detected and starts the calculation of the speed ratio R (k) after the number of times the pulse signal is input becomes two or more. On the other hand, when the number of times the pulse signal is input is less than two, Is designed to perform driving force control based on a preset vehicle-stop speed ratio.

In FIG. 11, first, in step S21, it is determined whether or not the pulse period counter 41 of the input shaft rotation sensor 11 (see FIG. 2) has overflown.
Then, the number of input axis sensor signal inputs is initialized to zero.

Subsequently, in step S23, it is determined whether or not the number of input shaft sensor signal inputs is two or more. If the number is less than two, the process proceeds to step S24, where the pulse cycle of the pulse cycle counter 41 on the input shaft side is determined. While it is determined whether or not it has been updated, if it has been updated twice or more, the process proceeds to step S27.

In step S24, if the pulse cycle of the pulse cycle counter 41 has been updated, step S25
The number of times of input shaft sensor signal input is incremented, and if not updated, the process proceeds to step S26, where the input shaft rotation speed Nin is set to zero.

If it is determined in step S23 that the number of times of input of the input shaft sensor signal is two or more, the process proceeds to step S27, and based on the update cycle Tin of the pulse cycle counter 41, as in the above embodiment. , Input shaft speed N
Calculate in.

Next, steps S28 to S34
Until the above, the same processing as the above steps S21 to S27 is performed on the pulse signal of the output shaft rotation sensor 12.

In steps S35 and S36, the input shaft speed Nin is determined in step S26 or S33.
Alternatively, it is determined whether or not one of the output shaft rotation speeds Nout is set to 0, and if at least one of them is set to 0, it is determined that the vehicle is stopped, and step S
Then, the process proceeds to step S38, where the preset stoppage gear ratio is set as the gear ratio R (k), and if both the input shaft rotation speed Nin and the output shaft rotation speed Nout are not 0, the input shaft side and the output shaft side It is determined that the pulse signal has been transmitted from the rotation sensors 11 and 12 twice or more, and it has been determined that the region has reached an area where the calculation accuracy of the speed ratio can be ensured.
Is output as the ratio (Nin / Nout) between the input shaft rotation speed Nin and the output shaft rotation speed Nout in the same manner as in the above embodiment.

Therefore, when the vehicle starts moving, the speed ratio R (k) = the speed ratio when the vehicle is stopped, ignoring the pulse signals of the input shaft rotation sensor 11 and the output shaft rotation sensor 12 up to the second time, respectively. The pulse signals detected by the input shaft rotation sensor 11 and the output shaft rotation sensor 12 are 2
After the first time, the input shaft rotation speed Nin and the output shaft rotation speed Nout are calculated based on these detected pulse signals to obtain the speed ratio R (k). As described above, when the vehicle speed VSP starts near 0, among the pulses Pi and Po generated by the input / output shaft rotation sensors 11 and 12, in FIG. 13, the first and second pulses Pi1, Pi2 and Po1, Po2
By ignoring the above, the calculation accuracy can be improved by starting the calculation of the gear ratio from the second and subsequent pulses Pi3 and Po3, and the driving force control can be performed with high accuracy from a low vehicle speed range. .

That is, the relationship between the rotation speed of the input / output shaft and each pulse period is as shown in FIG.
Since the angle / rotational speed is equivalent to one tooth of the gear, the pulse cycle is rapidly reduced after the first few pulses at the time of starting, and the phase difference between the pulses generated by the input shaft rotation sensor 11 and the output shaft rotation sensor 12 is also reduced. As a result, as described in the above-described conventional example, it is possible to suppress the occurrence of a speed ratio calculation error due to a longer period of the pulse signal, and to prevent a periodic fluctuation. As a result, it is possible to perform accurate driving force control by improving the calculation accuracy of the gear ratio.

The stationary gear ratio set in step S38 is a value set in advance in consideration of the frequency of use and error, and is, for example, the maximum gear ratio Rmax (minimum Low gear ratio) or the value learned during deceleration. The gear ratio is set.

Although the number of pulses to be ignored at the time of starting is set to 2, this number may be appropriately changed according to the rotation speed of the input / output shaft rotation sensors 11 and 12 and the input / output shaft. May be ignored.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a driving force control device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a controller.

FIG. 3 is a flowchart illustrating a gear ratio calculation process performed by the controller.

FIG. 4 is a flowchart illustrating a gear ratio calculation process performed by a controller according to the second embodiment.

FIG. 5 is a flowchart illustrating a gear ratio calculation process performed by a controller according to the third embodiment.

FIG. 6 is a flowchart illustrating a gear ratio calculation process performed by a controller according to the fourth embodiment.

FIG. 7 is a flowchart illustrating a gear ratio calculation process performed by a controller according to the fifth embodiment.

FIG. 8 is a flow chart showing a sixth embodiment and illustrating a gear ratio calculation process performed by a controller.

FIG. 9 is a flowchart illustrating a gear ratio calculation process performed by a controller according to the seventh embodiment.

FIG. 10 is a flowchart illustrating an operation of calculating a gear ratio performed by a controller according to the eighth embodiment.

FIG. 11 is a flowchart showing a ninth embodiment and illustrating a gear ratio calculation process performed by a controller.

FIG. 12 shows a conventional example, shows a state of speed ratio detection at the time of starting performed by a driving force control device, and shows a relationship between a lapse of time and an input / output shaft rotation speed.

FIG. 13 also shows a conventional example, shows how a gear ratio is detected at the time of starting, and shows the relationship between the passage of time, the input / output shaft rotation speed, and the gear ratio.

FIG. 14 is a graph showing a relationship between a pulse period of a rotation sensor and a rotation speed of a shaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Controller 11 Input shaft rotation sensor 12 Output shaft rotation sensor 40 Gear ratio detection part 41, 42 Pulse period counter 43 Gear ratio calculation part

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F16H 63:06 (72) Inventor Michinori Iwasaki 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Yoshinori Tanaka 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Tomoya Kimura 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. 2 Takaracho Nissan Motor Co., Ltd. F-term (reference) 3J052 AA04 AA19 CA21 CB01 EA04 FA01 FB31 GC03 GC13 GC23 GC43 GC44 GC72 HA13 KA01 LA01

Claims (14)

[Claims] 1. A target driving force setting means for setting a target driving force based on a driving state of a vehicle, and an input for detecting an input shaft rotation speed based on a period of a signal synchronized with a rotation of an input shaft of the automatic transmission. Shaft rotation number detecting means, output shaft rotation number detecting means for detecting the output shaft rotation number based on the cycle of a signal synchronized with the rotation of the output shaft of the automatic transmission, and, based on these input shaft rotation number and output shaft rotation number, Speed ratio calculating means for calculating the speed ratio of the automatic transmission at a predetermined calculation period; target engine torque setting means for setting a target torque of the engine based on the result of calculating the target driving force and the speed ratio; In a driving force control apparatus for a vehicle, comprising: a driving force control means for controlling an engine so as to attain a target engine torque, wherein the speed ratio calculating means comprises: a cycle of a rotation synchronization signal of an input shaft; Wherein at least one of the cycles is longer than the calculation cycle of the gear ratio calculation means, a gear ratio correction means for correcting the calculation result of the gear ratio is provided. apparatus. 2. The gear ratio correction means according to claim 1, wherein the period of the rotation synchronization signal of the input shaft and the period of the rotation synchronization signal of the output shaft are the same.
2. The vehicle driving force control device according to claim 1, wherein when at least one of the periods is longer than the operation period of the speed ratio operation means, the maximum speed ratio of the automatic transmission is set as an operation result. 3. The method of claim 2, wherein the speed ratio correction unit is configured to determine a period of the rotation synchronization signal of the input shaft and a period of the rotation synchronization signal of the output shaft.
2. The vehicle driving force control device according to claim 1, wherein when at least one of the periods is longer than the operation period of the speed ratio operation means, the previous operation result is set as the current speed ratio. 4. The speed ratio correction means calculates a speed ratio between a period of a rotation synchronization signal of an input shaft and a period of a rotation synchronization signal of an output shaft near or at a maximum speed ratio of an automatic transmission. The one that is larger than the operation cycle of the means,
4. The driving force control device for a vehicle according to claim 2, wherein the comparison is made with the calculation cycle. 5. A target driving force setting means for setting a target driving force based on a driving state of a vehicle, and an input for detecting an input shaft rotation speed based on a cycle of a signal synchronized with a rotation of an input shaft of the automatic transmission. Shaft rotation number detecting means, output shaft rotation number detecting means for detecting the output shaft rotation number based on the cycle of a signal synchronized with the rotation of the output shaft of the automatic transmission, and, based on these input shaft rotation number and output shaft rotation number, Speed ratio calculating means for calculating the speed ratio of the automatic transmission at a predetermined calculation period; target engine torque setting means for setting a target torque of the engine based on the result of calculating the target driving force and the speed ratio; A driving force control device for a vehicle, comprising: a driving force control unit that controls an engine to attain a target engine torque; wherein the speed ratio calculating unit includes: a ratio of a period of a rotation synchronization signal of an input shaft to the calculation period; Among the ratio of the period of the operational cycle of the rotation synchronizing signal of the force axis,
A driving force control device for a vehicle, further comprising a speed ratio correction unit that corrects a result of calculating the speed ratio when at least one of the ratios is smaller than a preset value. 6. The speed ratio correction means may be configured such that at least one of a ratio of a period of a rotation synchronization signal of an input shaft to the operation period and a ratio of a period of a rotation synchronization signal of an output shaft to the operation period is determined. The driving force control device for a vehicle according to claim 5, wherein when the value is smaller than a preset value, the maximum speed ratio of the automatic transmission is set as a calculation result. 7. The speed ratio correction unit may be configured to determine that at least one of a ratio of a period of a rotation synchronization signal of an input shaft to the operation period and a ratio of a period of a rotation synchronization signal of an output shaft to the operation period is equal to 6. The driving force control device for a vehicle according to claim 5, wherein when the value is smaller than a preset value, a previous calculation result is set as a current gear ratio. 8. A target driving force setting means for setting a target driving force based on a driving state of a vehicle, and an input for detecting an input shaft rotation speed based on a period of a signal synchronized with a rotation of an input shaft of the automatic transmission. Shaft rotation number detecting means, output shaft rotation number detecting means for detecting the output shaft rotation number based on the cycle of a signal synchronized with the rotation of the output shaft of the automatic transmission, and, based on these input shaft rotation number and output shaft rotation number, Speed ratio calculating means for calculating the speed ratio of the automatic transmission at a predetermined calculation period; target engine torque setting means for setting a target torque of the engine based on the result of calculating the target driving force and the speed ratio; A driving force control device for a vehicle, comprising: driving force control means for controlling an engine so as to attain a target engine torque, wherein the speed ratio calculating means comprises a small one of the detected input shaft rotation speed and output shaft rotation speed. If Kutomo one is smaller than the minimum rotational speed set in advance, the driving force control apparatus for a vehicle, characterized in that a gear ratio correcting means for correcting the calculation result of the transmission ratio. 9. The automatic transmission according to claim 1, wherein at least one of the detected input shaft rotation speed and the output shaft rotation speed is smaller than a preset minimum rotation speed. The driving force control device for a vehicle according to claim 8, wherein is set as a calculation result. 10. The speed ratio correction means, if at least one of the detected input shaft rotation speed and output shaft rotation speed is smaller than a preset minimum rotation speed, compares the previous calculation result with the current calculation result. 9. The driving force control apparatus for a vehicle according to claim 8, wherein the setting is performed as a speed change ratio. 11. A target driving force setting means for setting a target driving force based on a driving state of a vehicle, and detecting an input shaft rotation speed based on a cycle of a pulse signal synchronized with a rotation of an input shaft of the automatic transmission. An input shaft rotation number detecting means; an output shaft rotation number detecting means for detecting an output shaft rotation number based on a cycle of a pulse signal synchronized with the rotation of the output shaft of the automatic transmission; Speed ratio calculating means for calculating the speed ratio of the automatic transmission from the number in a predetermined calculation cycle; and target engine torque setting means for setting a target torque of the engine based on the calculation result of the target driving force and the speed ratio. And a driving force control device for controlling the engine so as to attain the target engine torque. The speed ratio calculating means comprises: an input shaft rotational speed detecting means immediately after the vehicle starts moving. And a gear ratio correcting means for correcting the calculation result of the gear ratio until the number of pulse signals detected by the output shaft rotation number detecting means exceeds a preset number. Control device. 12. The vehicle according to claim 11, wherein the gear ratio correction unit sets a preset value as a current gear ratio until the number of pulse signals becomes at least two or more. Driving force control device. 13. The speed ratio correcting means detects the start of the vehicle when the cycle of the pulse signal detected by the input shaft speed detecting means and the output shaft speed detecting means becomes equal to or less than a preset cycle. The driving force control device for a vehicle according to claim 11, further comprising a start detection unit. 14. The speed change ratio correction means, wherein the maximum speed change ratio of the automatic transmission is maintained until the number of pulse signals detected by the force shaft speed detection means and the output shaft speed detection means becomes at least two or more. 13. The driving force control device for a vehicle according to claim 12, wherein is set as a current gear ratio.