JP3015965B2 - Vehicle constant speed driving control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a constant-speed traveling control device for a vehicle that controls a throttle opening so that an actual vehicle speed converges to a target vehicle speed.
More specifically, the present invention relates to a constant-speed traveling control device for a vehicle that determines the end of climbing.

(Prior Art) For example, as described in Japanese Patent Application Laid-Open No. 61-285233, conventionally, an engine is controlled so that the actual vehicle speed converges on the target vehicle speed based on a deviation between the actual vehicle speed and the target vehicle speed. 2. Description of the Related Art There is known a constant-speed traveling control device that controls the opening of a throttle valve (throttle opening) to cause a vehicle to travel at its target vehicle speed.

By the way, in the above-mentioned constant speed traveling control, when the vehicle enters the uphill while traveling at a constant speed, the shift speed is shifted down, for example, from the 4th speed to the 3rd speed so as to increase the torque, thereby increasing the torque at the uphill speed. Control that keeps traveling and shifts up from third gear to fourth gear when a predetermined time has elapsed after downshifting is known.

However, in such a method of shifting up after a lapse of a predetermined time, if the required traveling time is longer than the predetermined time and the climbing board is used, the upshift is performed in the middle of the climbing, whereby the vehicle speed decreases and the downshift is immediately performed. In the case of a climbing board in which the required traveling time is shorter than the above-mentioned predetermined time, 3 hours after the completion of the climbing.
The vehicle travels at high speed, which causes problems such as a decrease in fuel efficiency.

Therefore, when the downshift is performed as described above during climbing, control may be performed to shift up from third speed to fourth speed in synchronization with the end of the climbing, thereby preventing a reduction in fuel efficiency.

In performing the above control, it is necessary to detect the end of the climbing. For example, a method of detecting a throttle return amount (a throttle opening decrease amount) from a predetermined reference throttle opening after downshifting may be detected. And
When it exceeds a predetermined value, it is conceivable to perform a pitching end determination. The throttle return amount may be, for example, a return amount from a throttle opening in a steady running state during uphill running after downshifting, or a maximum throttle opening after downshifting, as described later. The return amount may be the return amount from another reference, or may be the return amount from another reference.

(Problems to be Solved by the Invention) However, in the method of determining the end of climbing and shifting up according to the above, an abnormality occurs in the end of climbing due to, for example, a failure of the means for determining the end of climbing, and It is conceivable that the determination is output irrespective of the end of the climbing or that no output is output.

Then, when the pitching end determination is output irrespective of the end of the pitching, the upshift is also performed irrespective of the end of the pitching, and the above-described problems such as shift hunting and a decrease in fuel consumption are remarkable. Will occur.

Therefore, in the case where the completion of the pitching is determined as described above and the upshift is performed based on the determination, it is desirable to take measures against the abnormality in the determination of the completion of the pitching.

In view of the above circumstances, an object of the present invention is to provide a constant-speed traveling control device for a vehicle that can take measures against abnormalities in the determination of the end of pitching and can suppress occurrence of shift hunting and reduced fuel consumption during abnormal times. is there.

(Means for Solving the Problems) In order to achieve the above object, a constant-speed traveling control device for a vehicle according to the present invention provides a constant-speed traveling control device for controlling a throttle opening such that an actual vehicle speed converges to a target vehicle speed. A downshifting means for shifting down the transmission under a predetermined condition in order to maintain a constant speed traveling state during the uphill traveling; and when the throttle return amount after the downshift exceeds a predetermined value, the uphill climbing is completed. Climbing end determination means for performing determination; abnormality determination means for determining that the climbing end determination means is abnormal if the climbing termination determination is performed within a predetermined time for abnormality determination set in advance after the downshift; If the abnormality determination is not performed in response to the outputs of the climbing termination determination means and the abnormality determination means, the transmission is shifted up based on the climbing termination determination, and Shift-up means for shifting up after a predetermined shift-up predetermined time longer than the abnormality determination predetermined time after the shift-down when the abnormality determination is performed. .

(Operation) The downshifting is performed to maintain the constant speed traveling. Therefore, during downshifting, the vehicle speed usually tends to decrease and the throttle opening is increasing (opening). Therefore, immediately after the downshift, the vehicle speed further decreases due to the downshift, and as a result, the throttle opening tends to further increase.

Therefore, even if the pitching is completed immediately after the downshift, the pitching end determination is made because the throttle opening tends to further increase at that time and there is a time delay in the recovery of the vehicle speed due to the completion of the pitching. If the determination is made based on a large throttle return amount after downshifting, there is no possibility that the climbing end determination is inherently made for a predetermined short time after downshifting. When it is performed, the end determination can be determined to be abnormal.

Since the constant-speed traveling control device for a vehicle according to the present invention is configured as described above, it ends within the predetermined time after the downshift (the above-described predetermined time for abnormality determination) in which the decision to end the climbing is not output. When the determination is output, it is possible to appropriately determine that the pitching end determination means is abnormal, and in that case, the predetermined predetermined time (predetermined time for upshifting) without depending on the determination of the end. Since the upshift is performed after the lapse of time, it is possible to prevent a remarkable occurrence of the shift hunting, a decrease in fuel efficiency, and the like due to an abnormality of the climbing completion determination means, and to secure the performance equivalent to that of the related art.

(Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

 FIG. 1 is an overall configuration diagram of the embodiment.

Basic Configuration A throttle valve 3 for adjusting the amount of intake air is interposed in an intake passage 2 of the engine 1, and the throttle valve 3 is opened and closed by a throttle actuator 4, and its opening is controlled. Reference numeral 5 has a plurality of shift solenoids 6a to 6c and a lock-up solenoid 7, and a hydraulic circuit is switched by a combination of ON and OFF of the shift solenoids 6a to 6c to selectively fasten a plurality of hydraulic fastening elements. As a result, the transmission mechanism is controlled to switch to a plurality of shift speeds. The lock-up clutch (not shown) in the torque converter is engaged or released by turning on and off the lock-up solenoid 7.

As the throttle actuator 4, for example, DC
Although it is possible to use a motor or the like, in this embodiment,
A negative pressure actuator as shown in FIG. 2 is employed.

The actuator 4 includes a negative pressure chamber 41 for accumulating a negative pressure of the engine 1 and an atmosphere chamber 42 communicating with the atmosphere.
A diaphragm 43 operated by the negative pressure of the engine 1 introduced into the negative pressure chamber 41; a spring 44 for urging the diaphragm 43 in a direction opposite to the arrow A;
Rod 45 and throttle wire connected to the rod 45
46, a release pipe 47a communicating with the atmosphere, a release control valve 47 of an electromagnetic proportional type capable of communicating the release pipe 47a with the negative pressure chamber 41, and a pull pipe to which the negative pressure of the engine 1 is supplied. Path 48a and an electromagnetic proportional pull control valve 48 that can communicate the pull pipe 48a with the negative pressure chamber 41.The duty control is performed on the release control valve 47 and the solenoid of the pull control valve 48 by duty control. By controlling the negative pressure of the engine 1 with respect to the negative pressure chamber 41, the diaphragm 43 and the rod are controlled.
45 is reciprocated in the direction of arrow A to open and close the throttle valve 3 via the throttle wire 46.

The throttle valve 3 and the automatic transmission 5 are controlled by a controller 8.

That is, the controller 8 performs an engine output control and a shift control by a throttle control for controlling the vehicle speed, and outputs a throttle valve control signal A to the throttle actuator 4 to control the throttle valve 3 to automatically control the throttle valve 3. In order to control the transmission 5, a shift control signal B and a lock-up control signal C are output to the shift solenoids 6a to 6c and the lock-up solenoid 7, respectively. The throttle valve control signal A is composed of a release control signal A ₁ and the pull control signal A ₂ Metropolitan is input to release the control valve 47 and the pull control valve 48 of the throttle valve actuator 4, the release control signals A ₁ and the pull control signal a ₂ has its a pulse signal for variably controlling the opening degree of the release control valve 47 and the pull control valve 48 by the duty ratio.

The controller 8 includes a vehicle speed signal Vn from a vehicle speed sensor 9 for detecting a vehicle speed (actual vehicle speed) for controlling the throttle valve 3 and the automatic transmission 5, and an accelerator pedal.
An accelerator opening signal α from an accelerator sensor 11 for detecting an amount of depression (accelerator opening) of 10, a brake signal BR from a brake switch 12 for detecting a brake operation, and a throttle sensor for detecting an opening of the throttle valve 3. 13 and a gear position signal GP from a gear position sensor 14 for detecting the shift position of the transmission 5.
And a shift mode signal M from the mode switch 15 are input, respectively, and operation signals (ON, OFF) from the main switch 16, the set switch 17, the resume switch 18, and the coast switch 19 as the constant-speed traveling operation switches. Each is entered. The main switch 16 is for turning on the power of the cruise control device to put the entire system in a standby state, and the set switch 17 is
The resume (automatic return) switch 18 is used to set a desired target vehicle speed Vo, and is used for performing constant speed traveling again at the target vehicle speed Vo before the release after releasing the constant speed traveling control. The coast switch 19 is for performing desired deceleration during constant speed traveling control.

Configuration for constant-speed traveling control during climbing In the constant-speed traveling control device, when entering the climbing, shift down as appropriate to maintain constant speed traveling at the target vehicle speed Vo, and shift up when climbing is completed Is performed. Therefore, this constant speed traveling control device
As shown in FIG. 3, the shift-down means 50, the steady running determination means 51, the first climbing completion determination means 52, the second climbing completion determination means 53, the first and second climbing completion determination means 52, 53
First and second abnormality judging means 54 and 55 for judging abnormality
And a shift-up means 56. Each of these means is constituted by the controller 8.

 Each of these means will be described later in detail.

Overview of Basic Low-Speed Travel Control Next, an overview of basic low-speed travel control by the controller 8 will be described with reference to the flowchart shown in FIG.

FIG. 4 shows a main routine.
At the start of operation, predetermined system initialization (S1) is performed, detection signals from the various sensors are read, and various information necessary for control is input from these (S2).

S3 is for determining whether or not a condition for starting automatic speed control (ASC) including cruise control is satisfied.
The condition for starting the automatic speed control is when the main switch 16 is turned on, the shift position is in the D range, and the vehicle speed is equal to or higher than a set value (for example, 40 km / h). The condition for canceling the automatic speed control is when the start condition is not satisfied or when the brake is operated.

When the conditions for the automatic speed control are satisfied, the operation shifts to the automatic speed control, and the set switch 17 and the resume switch 1
8. Mode setting control such as a vehicle speed feedback control mode or an accelerator acceleration mode is performed in response to the operation of the coast switch 19, the accelerator and the brake operation (S4),
The target throttle opening To corresponding to each mode is set and controlled (S5). If the automatic speed control condition is not satisfied, the routine shifts to the normal throttle control, and the throttle opening To is set and controlled based on the accelerator operation amount (S6).

As described above, a throttle control signal A corresponding to the target throttle opening To set in S5 or S6 is output to the throttle actuator 4 (S7), the throttle valve 3 is operated to the target opening To, and the vehicle speed Vn , Throttle opening
The gear stage is set by the TH, the accelerator opening α, etc., and the gearshift control for outputting the control signals B and C to the solenoids 6a to 6c and 7 of the automatic transmission 5 is performed (S8). Execute every 30 msec).

In the above-described vehicle speed feedback control mode, a detailed routine is not shown, but the actual vehicle speed Vn is set to the target vehicle speed Vo by PI-PD calculation or the like based on a deviation between the actual vehicle speed Vn and the target vehicle speed Vo and a change amount of the actual vehicle speed Vn. Calculates the throttle opening Tv required to converge to the target throttle opening.
By setting to To, feedback control is performed.

If a brake operation is performed during the above-mentioned vehicle speed feedback control, the vehicle speed feedback control is stopped and the mode shifts to the normal throttle control mode.

In the normal throttle control mode, the detailed routine is omitted, but the accelerator opening α and the shift mode M
(Economy, Normal, Power), select the basic throttle opening map corresponding to the gear shift mode, and from this map, based on the detected throttle opening α, the basic throttle opening Tb according to the gear position. Various corrections such as an accelerator depression speed correction, a vehicle speed correction, and a water temperature correction are performed, and the corrected throttle opening is set as a target throttle opening To.

Further, when the accelerator pedal is depressed by a predetermined value (α = 5%) or more during the shift traveling control, the mode shifts to the accelerator acceleration mode. In this accelerator acceleration mode, a detailed routine is omitted, but the target throttle opening Tv corresponding to the target vehicle speed Vo in the vehicle speed feedback control up to that time is omitted.
And the basic throttle opening Tb corresponding to the depressed accelerator opening α is obtained from a preset map, and the sum Tv + Tb of the two is set as the target throttle opening To.

As described above, in the constant-speed traveling control, in the constant-speed traveling control, a downshift is appropriately performed in order to maintain the constant-speed traveling, and when the climbing is completed, the termination of the climbing is determined. Control for shifting up is performed based on the end determination.

In the downshifting, it is difficult to maintain the target speed Vo by the throttle opening control at the current gear stage during the uphill traveling by the downshifting means 50,
This is performed when it is determined that downshifting is necessary. The shift-down means 50 according to the present embodiment
The actual vehicle speed Vn with respect to Vo is a predetermined threshold value β set in advance.
It is determined that the downshift is necessary when the speed is lowered (for example, 8 km / h) or more. The determination of the end of the climbing will be described later in detail.

Hereinafter, the constant-speed running control in the climbing will be described with reference to FIG.

FIG. 5 shows a substantially straight uphill with a substantially constant inclination angle, where the uphill is long (solid line) and short (2).
(Dash-dot line).

First, for long pitched, as shown in FIG. 5, it is assumed that the constant-speed running control is performed at the fourth speed, when entering the mound at that time t ₁ when the actual vehicle speed Vn is reduced by increase of the load Then, control to increase the throttle opening is performed to maintain the actual vehicle speed Vn at the target vehicle speed Vo.

However, even if the throttle opening is increased in such a manner, the actual vehicle speed Vn continues to decrease, and the deviation Δ between the actual vehicle speed Vn and the target vehicle speed Vo
Upon reaching V (ΔV = Vo-Vn) threshold which is preset beta, and outputs the down-shifting signal e at the time t ₂ said downshift means 50 performs a shift-down determination, the automatic transmission 5 Is shifted down to the third speed.

After the downshift is performed, the actual vehicle speed immediately follows
Vn decreases and the throttle opening increases accordingly.However, the vehicle speed immediately increases and the throttle opening decreases accordingly, and eventually the vehicle speed converges to the target vehicle speed Vo and the throttle opening becomes almost constant. , And the vehicle enters the steady driving state D. Thereafter, the steady running state D continues until just before the end of the uphill climbing, and as soon as the uphill climbing is completed, the throttle opening is greatly reduced due to the reduction of the load, and the throttle opening returns to the throttle opening before entering the uphill.

 Next, the case of short climbing will be described.

In the case of a short pitch, the operation is the same as in the case of the long pitching until the vehicle enters the pitching and shifts down.However, in the case of the short pitching, before shifting to the steady driving state after the downshift, for example, as shown in the drawing, throttle opening pitched at t ₃ when the middle is completed has risen just after down and pitched ends throttle opening continues to increase thereafter until t ₄ when the relationship between the vehicle speed, the maximum value at t ₄ time Then, it is greatly reduced from there, and returns to the throttle opening before entering the climbing.

Next, a description will be given of the determination of the end of climbing.

As described above, when the downshift is performed during the uphill running, the upshift is performed when the uphill is completed, and therefore, the end of the uphill is determined.

The above-described climbing end determination is basically made in consideration of the fact that, when the climbing is completed and the climbing is completed and the vehicle shifts to the flat road traveling, the throttle opening is reduced to a certain extent by the load reduction compared with the climbing traveling. The decrease in the opening (throttle return amount) is detected, and the end of climbing is determined based on the detection.

Hereinafter, the termination determination will be described separately for long climbing and short climbing.

In the case of a long uphill, the uphill end determination is that, in the case of a long uphill, since a steady running state exists after downshifting, the steady running state is detected, and the throttle opening decreases by a predetermined value or more from the value in the steady running state. This is done by detecting that

Specifically, first, the steady-state running determination means 51 shown in FIG.
Thus, a steady running state D during climbing running as shown in FIG. 5 is determined.

The steady running state refers to a state in which the actual vehicle speed Vn converges to the target vehicle speed Vo under a substantially constant throttle opening as described above. The state is, for example, a deviation ΔV between the actual vehicle speed Vn and the target vehicle speed Vo. (A differential value of the actual vehicle speed Vn). Therefore, the steady running state can be determined based on whether or not the deviation ΔV and the acceleration are equal to or smaller than a predetermined threshold value. In the present embodiment, the determination as to whether or not the difference is equal to or smaller than the predetermined value is made fuzzy. Performed by theory.

That is, after the downshift signal e output from the downshift unit 50, the vehicle speed deviation ΔV, and the acceleration are input, the steady running determination unit 51 performs the fuzzy logic operation after the downshift signal e is input. The center of gravity with respect to the vehicle speed deviation ΔV and the acceleration is obtained based on the input membership function and the output membership function, and it is determined whether the center of gravity is larger or smaller than a predetermined threshold value γ for steady running determination. If it is large, it is determined that the vehicle is in a steady running state. The details of the fuzzy logic will be omitted.

Next, based on the detected steady running state, the first
The uphill ending determination means 52 makes an uphill ending determination.

The first climbing completion determination means 52 determines that the throttle opening is
When the threshold value for climbing completion determination δ ₁ which is set separately from the value in the steady running state is reduced by not less than ₁ , that is, the throttle return amount ΔTH ₁ from the steady running state is reduced to the threshold value δ _1.
When this is the case, the completion of pitching is determined. More specifically, as shown in FIG. 5, 4 → 3 downshift time t ₂
Output time of the pull control signal A ₂ and the release control signal from the
Begin accumulating output time and the difference of _{A 1 (A 2 -A 1)} . This integration is based on both control signals A ₁ , A
The _second output time, the A ₁ (-), it means that by accumulating each output of A ₂ as (+). Then, upon receiving the input of the steady running determination signal f from the steady running determining means 51, the integrated amount at the time of the input, that is, the integrated amount in the steady running state is stored as a reference integrated amount, and thereafter every predetermined period. Subtract the current integrated amount from the reference integrated amount,
The subtraction value determines the end of the mound at the time of exceeding the threshold value [delta] _1.

Next, a description will be given of how to determine the end of uphilling in the case of short uphilling.

As described above, in the case of a short uphill where the slope ends before shifting to the steady driving state after the downshift, the return amount of the throttle cannot be obtained based on the throttle opening during the steady driving state. Is determined based on the return amount of the throttle from the maximum value of the throttle opening.

That is, the second climbing completion determination means 53 shown in FIG.
As shown in FIG. 5, the throttle opening return amount (decrease amount ΔTH ₂ ) from the maximum value of the throttle opening after the downshift (throttle opening at time t ₄ ) is calculated, and the return amount ΔTH ₂ is calculated. a determination outing ends when it becomes a preset threshold value [delta] ₂ or more. More specifically, as shown in FIG. 3, the downshift signal e,
The pull control signal A ₂ and the release control signal A ₁ are input, and the output time of the pull control signal A ₂ and the release control signal A ₁ from the point of 4 → 3 shift down as in the first climbing determination means 51.
It starts integration of the difference between the output time of the (A ₂ -A _1), that is, the output time of the two control signals A _1, A ₂ and outputted after downshifting, the A ₁ (-), the A ₂ ( Each time it is output as +), it is integrated. Then, the mound terminated when its accumulated amount of time from the maximum value by subtracting, the subtracted value exceeds the threshold value [delta] ₂ stores the maximum value of the integrated amount up to that time in a predetermined cycle judge.

Note that the first, the integrated value of the difference of the pull control signal A ₂ and the output time of the release control signal A ₁ in the second pitched end determination means 51, 53 at each time point to the end based on the accumulation start time It means throttle opening.

Abnormality Determination and Upshift Next, abnormality determination by the first and second abnormality determination units 54 and 55 and upshifting by the shiftup unit 56 will be described.

The first climbing end determining means 52 is provided with a first abnormality determining means 54 for performing an abnormality determination of the means 52, and the second climbing completion determining means 53 is provided with a second abnormality determining means 53 for determining an abnormality of the means 53.
An abnormality determining means 55 is provided.

Both of the climbing completion determination means 52 and 53 perform the climbing completion determination based on the large throttle return amount after downshifting. Therefore, as described above, the climbing completion determination is performed within a predetermined short time after downshifting. Is not possible. Based on such circumstances, the two abnormality determination means 54 and 55 determine that the uphill termination determination means 52 and 53 are abnormal when the uphill termination determination is performed within a predetermined short time after the downshift.

More specifically, the first abnormality determination unit 54, pitched end determination signal g ₁ and downshift means from the first pitched end determination means 52
A shift-down signal e from 50 is input, and a predetermined time (predetermined time for abnormality determination) ε is set after the shift-down.
When there is an input of the pitched end determination signal g ₁ within determines that the first pitched end determining unit 52 is abnormal, abnormality determination signal h ₁
Is output. The second abnormality determination unit 55 includes a shift-down signal e from the pitcher end determination signal g ₂ and downshift means 50 from the second pitched end determination means 53 is input, a preset predetermined time after the shift down (abnormality determination for a given time) when a outing end determination signal g ₂ in ε is determined that the second pitched end determining unit 53 is abnormal, and outputs an abnormality determination signal h _2.

The predetermined time ε for abnormality determination may be the same for the first abnormality determination unit 54 and the second abnormality determination unit 55, or may be different. In addition, as the predetermined time for abnormality determination, it is possible to set an appropriate time for which it is assumed that the end of climbing after shifting down is not determined as described above, for example, 2 seconds or 3 to 4 seconds. can do.

Next, upshifting by the upshifting means 56 will be described.

As shown in FIG. 3, the upshift means 56 includes climbing end determination signals g ₁ and g ₂ from the first and second climbing end determining means 52 and 53, and first and second abnormality determining means 54. , an abnormality determination signal h _1, h ₂ from 55, down-shifting signal e from the shift-down means 50 is input, usually pitched end determination signal
In response to g ₁ and g ₂ , a 3 → 4 shift-up signal i is output, and the automatic transmission 5 is shifted up to the fourth speed. When the climbing end determination signal g ₁ is input, the abnormality determination signal h ₁ is simultaneously output. when the same time abnormality determination signal h ₂ when or is pitched end determination signal g ₂ is input when inputted is inputted, their pitched end determination signal g _1, the shift-up signal by g ₂ i
The shift-up signal i is output uniformly after a predetermined time (a predetermined time for shift-up) elapses after the shift-down, and the automatic transmission 5 is shifted up to the fourth speed.

Note that, as the predetermined time for upshifting, a time longer than the predetermined time for abnormality determination is set. The predetermined time for the upshift can be set to the same value as the predetermined time in the related art in which the upshift is performed uniformly after a predetermined time elapses after the downshift.
It can be 20 seconds.

(Effect of the Invention) Since the vehicle constant-speed traveling control device according to the present invention includes the abnormality determination means and the shift-up means as described above,
It is possible to appropriately detect an abnormality of the uphill exit determining means when the uphill exit determination is output within a predetermined time after the downshift (the above-mentioned abnormal determination predetermined time) in which the end determination is not originally output, and In this case, the shift-up operation is performed after a predetermined time (predetermined time for shift-up) elapses as before without depending on the end-of-pitch determination.
Performance comparable to that of the prior art can be ensured, and remarkable occurrences such as the shift hunting and a decrease in fuel efficiency due to an abnormality in the climbing end determination means can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall schematic view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a throttle actuator, FIG. 3 is a block diagram showing a part of a controller, and FIG. FIG. 5 is a flow chart showing a flow, and FIG. 5 is a time chart showing a control example in climbing. 50: downshifting means 52, 53 ... uphill end determination means 54, 55 ... abnormality determination means 56: upshifting means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI // F16H 59:66 (58) Fields investigated (Int.Cl. ⁷ , DB name) B60K 31/00 F02D 29/02 F02D 41 / 14 F02D 9/02 B60K 41/04

Claims (1)

(57) [Claims] 1. A constant-speed traveling control device for a vehicle, which controls a throttle opening so that an actual vehicle speed converges to a target vehicle speed, wherein a transmission is shifted under predetermined conditions to maintain a constant-speed traveling state during uphill traveling. Downshifting means for downshifting; climbing end determination means for performing climbing termination determination when a throttle return amount after the downshift exceeds a predetermined value; and within a predetermined abnormality determination predetermined time after the downshifting, Abnormality judging means for judging that the climbing end judging means is abnormal if the climbing end judging is performed, receiving the outputs of the climbing end judging means and the abnormality judging means,
If the abnormality determination is not performed, the transmission is shifted up based on the climbing termination determination, and if the abnormality determination is performed, a predetermined time longer than the predetermined time for abnormality determination after the downshift is set. And a shift-up means for shifting up after a lapse of a predetermined shift-up time.