JPH11123957A - Uphill start auxiliary device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uphill start auxiliary device which can always conduct complete and smooth uphill start regardless of the slope of a road surface of a vehicle load even with a worn clutch in a mechanical automatic- transmission. SOLUTION: In normal slope-starting, releasing conditions C1 to C4 are selected and braking force is released when stroke amount of a clutch reaches a prescribe stroke amount which is preset according to the slope. On the other hand, when the climbing slope S of a first prescribed value S4 or higher is detected (mainly in an area (b)), or the climbing slope S which is a second prescribed value S5 smaller than the first prescribed value S4 or higher is detected, and the degree α VL of a vehicle load which is a specified value α1 or higher is detected (in the case of stopping without complete contact of the clutch, the acceleration of a specified value α2 or lower is detected) (in an area (a)), a releasing condition C5 is selected, and the braking force is released only after a decrease in the prescribed amount of an engine rotational speed is once detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hill start assist device, and more particularly, to a hill start assist device applied to trucks, buses, and the like whose load weights vary greatly.

[0002]

2. Description of the Related Art Conventionally, as a vehicle transmission, an automatic transmission in which a shift operation is automated has been frequently used. In the case of a small vehicle, the automatic transmission mainly employs a torque converter instead of a clutch. However, in large vehicles such as buses and trucks, the transmission amount of the driving torque is large, and it is difficult for the torque converter to sufficiently transmit the driving torque.

Therefore, a mechanical automatic transmission using a mechanical transmission similar to a manual transmission and having a clutch device capable of automatically connecting and disconnecting to this transmission has been developed for large vehicles. Thus, even when the transmission drive torque is large, it is possible to automatically perform the shift by automatically controlling the clutch in accordance with the shift timing. Also, in such an automatic transmission with a clutch,
The clutch is automatically disengaged when the vehicle stops to avoid engine stall, and is automatically engaged when the vehicle restarts.

[0004] However, if the clutch is automatically controlled when the vehicle stops and starts, the vehicle may travel on an uphill road, although the road surface may be flat or downhill. In some cases, when the driver once releases his / her foot from the brake pedal when performing a so-called hill start, the vehicle may retreat, which is not preferable. In particular, when the weight (vehicle load) of the vehicle is large, the vehicle tends to retreat, and this problem is remarkable.

Therefore, when the vehicle is stopped, a braking force is automatically applied. When the vehicle starts moving, the braking force is released at a release timing corresponding to the gradient of the road surface, and the braking force is released based on the vehicle weight (vehicle load). A hill start assist device configured to change the release timing is disclosed in Japanese Patent Laid-Open No. 4-11024.
No. 0 publication.

[0006]

In the hill start assist device disclosed in the above-mentioned publications, etc., the control is easy. Therefore, the release of the braking force is determined based on the stroke amount of the clutch actuator for clutch connection / disconnection operation. I'm trying to do it. That is, in this device, the weight of the vehicle (vehicle load)
When the stroke amount reaches a predetermined amount, the braking force is released regardless of the change of the release timing according to.

However, the clutch is usually worn due to aging, and when the clutch is worn in this way, in the above-mentioned conventional method, the stroke is increased even though the clutch does not sufficiently transmit the driving torque to the driving wheels. When the amount reaches a predetermined amount, the braking force may be released. When the braking force is released while the clutch is slipping, the vehicle retreats inadvertently, particularly when the road gradient is large and the weight (vehicle load) of the vehicle is large, so that the driver cannot move in a so-called manner. You will feel a feeling of falling, which is not preferable.

Therefore, attention is paid to the fact that the engine speed once drops when the clutch is engaged, and control is performed when the engine speed drops to ensure that the driving torque is transmitted even when the clutch is worn. It is considered to release the power. However, if the braking force is released when the engine rotation speed decreases, the vehicle resembles a sudden start when the braking force is released when the road surface gradient or the vehicle weight (vehicle load) is not so large. This is not preferable.

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a mechanical automatic transmission that can be used on a slope even if a clutch is worn, irrespective of a road surface gradient or a vehicle load. It is an object of the present invention to provide a slope start assist device that can always start the vehicle reliably and smoothly.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, when starting on a normal slope,
Based on the first braking force release control means, when the stroke amount of the clutch reaches a predetermined stroke amount set in advance according to the gradient, the braking force applied when the vehicle stops is released. When the above-described ascending gradient is detected, or when the ascending gradient that is equal to or greater than a second predetermined value smaller than the first predetermined value is detected and the degree of the vehicle load equal to or greater than a specified value is detected, the second The braking force is released only after a predetermined decrease in the engine rotation speed is detected based on the braking force release control means.

Thus, when the grade of the road surface is large, or when the grade of the road surface is relatively large and the degree of the vehicle load is large, the engine speed is temporarily reduced and the clutch is half-clutched. When the vehicle enters the state, that is, when the clutch can reliably transmit the driving torque, the braking force applied when the vehicle is stopped is released, and the vehicle tends to retreat particularly when starting on a slope. Even in the situation, the release timing of the braking force is made appropriate irrespective of the wear of the clutch, and reliable and smooth start is possible.

According to the second aspect of the present invention, once the decrease in the engine speed is detected by the second braking force release control means, the predetermined stroke amount in the first braking force release control means is detected. Is corrected by learning to the actual stroke amount detected at that time, and the first braking force release control means keeps the release timing of the braking force appropriate regardless of the wear of the clutch. Therefore, even when the vehicle starts on a normal slope, the vehicle can be started reliably and smoothly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a drive system of a vehicle (such as a bus) to which a slope start assist device according to the present invention is applied. Referring to FIG. 2, a control unit (ECU) for the mechanical automatic transmission shown in FIG.
A block diagram showing the connection relation of the 80 is shown. Hereinafter, the configuration of the drive system of the vehicle including the slope start assist device will be described with reference to FIGS.

Referring to FIG. 1, a diesel engine (hereinafter, referred to as an engine) 1 has a fuel injection pump unit (hereinafter, referred to as an injection pump) for supplying fuel.
6 are provided. The injection pump 6 is a device that operates the pump by the output of the engine 1 transmitted via a pump input shaft (not shown) to inject fuel. The injection pump 6 is provided with a control rack (not shown) for adjusting the fuel injection amount, and further provided with a rack position sensor 9 for detecting a rack position (control rack position) SRC of the control rack. Have been. In the vicinity of the pump input shaft, an engine rotation sensor (engine rotation speed detecting means) 8 which detects the rotation speed of the pump input shaft and detects the rotation speed of the output shaft 2, that is, the engine rotation speed Ne, based on the rotation speed. Is attached.

An engine output shaft 2 extends from the engine 1, and the engine output shaft 2 is connected to an input shaft 20 of a gear type transmission (hereinafter simply referred to as a transmission) 4 via a clutch device 3. ing. As a result, the output of the engine 1 is transmitted to the transmission 4 via the clutch device 3, and the transmission 4 shifts. The transmission 4 is a mechanical automatic transmission having, for example, five forward gears (first gear to fifth gear) in addition to the reverse gear, and can perform not only automatic gear shifting but also manual gear shifting. I have. And the clutch device 3
Is configured to automatically control connection / disconnection when the transmission 4 is automatically shifted and when the vehicle stops and starts (clutch connection / disconnection control means).

The clutch device 3 is an ordinary machine in which a clutch plate 12 is pressed against a flywheel 10 by a pressure spring 11 to establish a connection state, while a clutch plate 12 is separated from the flywheel 10 to establish a disconnection state. The operation of the friction clutch can be automatically performed. That is, the clutch plate 12 can be automatically operated by the clutch actuator for clutch connection / disconnection, that is, the clutch actuator 16 via the outer lever 12a.

More specifically, an air tank 34 is connected to the clutch actuator 16 via an air passage 30 which is an air supply passage. Accordingly, when the working air is supplied from the air tank 34 through the air passage 30, the clutch actuator 16 automatically operates.
As a result, the clutch plate 12 moves, and the clutch device 3
Will be automatically connected and disconnected.

Actually, the air passage 30 is provided with an electro-pneumatic proportional control valve 31 which is driven in response to a signal from the ECU 80 and performs the flow and cutoff of the working air.
When supplied from the CU 80 to the electropneumatic proportional control valve 31, working air is supplied from the air tank 34 to the clutch actuator 16 via the electropneumatic proportional control valve 31, the clutch actuator 16 is operated, and the clutch device 3 is disengaged. You. On the other hand, when the supply of the drive signal is stopped, the supply of the working air from the air tank 34 to the clutch actuator 16 is cut off, and the clutch actuator 16
The internal working air is exhausted to the atmosphere, and the clutch device 3 is brought into the connected state by the action of the pressure spring 11.

The clutch actuator 16 includes:
The moving amount of the clutch plate 12, that is, the clutch stroke amount S
A clutch stroke sensor (stroke amount detecting means) 17 for detecting CL is attached, and the clutch stroke sensor 17 is electrically connected to the ECU 80. An air passage 39 branches from the air passage 30 and extends at an end of the air passage 39.
2 are connected. The air master 42 is an actuator for generating a braking force on the wheels by operating the wheel brake 40, and is driven when operating air is supplied from the air tank 34 through the air passage 39 to apply a braking force to the wheel brake 40. Occur. Although only one wheel brake 40 and one air master 42 are shown here, these wheel brakes 40 and air master 42 are provided for each wheel.

Actually, an electromagnetic valve MVQ44 driven by a signal from the ECU 80 is interposed in the air passage 39, and is supplied from the air tank 34 to the air master 42 according to the operation / non-operation of the electromagnetic valve MVQ44. Switching between air cutoff and communication is controlled. When the solenoid valve MVQ44 is activated and the air is shut off, the wheel brake 40
Will be maintained.

More specifically, the ECU 80 is electrically connected to a hill start assist device operation permission switch (SW) 52 which outputs an ON signal when the brake pedal 50 is depressed and senses a predetermined pedal force or more. And solenoid valve M
VQ44 is mainly a hill start assistance device operation permission SW
The valve is closed in response to the ON signal of 52, whereby the braking force of the wheel brake 40 is maintained.

The change lever 60 is a select lever of the transmission 4 and is provided with an N (neutral) range, an R (reverse) range, and a D (drive) range corresponding to an automatic shift mode. The change lever 60 is provided with a select position sensor 62 for detecting each range position.
80. On the other hand, the ECU 80 is connected to a gear shift unit 64 for meshing gears of the transmission 4, that is, switching gear positions. Accordingly, when a position signal is supplied from the select position sensor 62 to the ECU 80, a drive signal is output from the ECU 80 to the gear shift unit 64 in accordance with the position signal, whereby the gear shift unit 64 operates and the transmission The gear position of No. 4 is switched to the selected desired select range. Although not described in detail, when the select position is in the D range, automatic shift control is performed in accordance with the driving state of the vehicle, and the gear position is switched based on the automatic shift control. .

The gear shift unit 64 has an electromagnetic valve 66 that is operated by an operation signal from the ECU 80, and a power cylinder (not shown) that operates a shift fork (not shown) in the transmission 4. The power cylinder is connected to the air passage 30 via the electromagnetic valve 66 and the air passage 67. That is, when an operation signal is given from the ECU 80 to the electromagnetic valve 66, the electromagnetic valve 66 opens and closes in accordance with the operation signal, and the power cylinder is operated by supplying operating air from the air tank 34. Thereby, the meshing state of the gears of the gear transmission 4 is appropriately changed. Here, the solenoid valve 66
Although only one shift fork is shown, a plurality of shift forks are actually provided, and a plurality of power cylinders are provided corresponding to the plurality of shift forks, and the solenoid valve 66 also corresponds to the plurality of power cylinders. A plurality is provided.

In the vicinity of the gear shift unit 64 of the transmission 4, a gear position sensor 68 for detecting each gear position is attached and electrically connected to the ECU 80. , Ie, the gear position signal. Accelerator pedal 70
Is provided with an accelerator opening sensor 72, which is also electrically connected to the ECU 80. The accelerator opening sensor 72 outputs the amount of depression of the accelerator pedal 70, that is, accelerator opening information VA.

The output shaft 76 of the transmission 4 has a vehicle speed V
A vehicle speed sensor 78 for detecting and outputting the vehicle speed is provided. The vehicle speed sensor 78 is also electrically connected to the ECU 80. Reference numeral 82 in FIG. 1 indicates an engine control unit provided separately from the ECU 80. The engine control unit 82 is a device that supplies a signal from the ECU 80 corresponding to information from each sensor and accelerator opening information VA to an electronic governor (not shown) in the injection pump 6. Drive control is performed. That is, when a command signal is supplied from the engine control unit 82 to the electronic governor, the control rack operates to perform an operation to increase or decrease the fuel, thereby controlling an increase or decrease in the engine rotation speed Ne. The detection information from the rack position sensor 9 and the engine rotation sensor 8 is transmitted to the ECU 8 via the engine control unit 82.
0 is supplied.

The ECU 80 includes a microcomputer (C
PU), a memory, and an interface for performing input / output signal processing. The input side interface of the ECU 80 includes the clutch stroke sensor 17, the hill start assist device operation permission SW 52, the select position, as described above. In addition to the sensor 62, the gear position sensor 68, the accelerator opening sensor 72, the vehicle speed sensor 78, the engine control unit 82, etc., a gradient sensor (gradient detecting means) 9
0 are respectively connected. The gradient sensor 90 is a sensor that detects and outputs the gradient S of the road surface based on the inclination angle of the vehicle in the front-rear direction. A release point adjustment switch (release point adjustment SW) 92 is further connected to the input side of the ECU 80. The function and the like of the release point adjustment SW 92 will be described later.

On the other hand, the solenoid valve 66, the engine control unit 82, the clutch actuator 16, the solenoid valve MVQ44 and the like are connected to the output interface of the ECU 80 as described above. Hereinafter, the operation of the slope start assist device configured as described above will be described.
When the main switch of the slope start assist device is on, the vehicle stops and the clutch device 3 is automatically disconnected,
When the hill start assist device operation permission SW 52 is turned on, a drive signal (cutoff signal) is supplied from the ECU 80 to the solenoid valve MVQ44, and the wheel brake 40 is held at a predetermined braking force (braking force holding means). After that, the accelerator pedal 70 is started and the accelerator opening degree V
A reaches, for example, 10% of the full opening and the engine speed Ne
Rises to some extent, the clutch device 3 is automatically engaged as described above, and the signal supplied to the solenoid valve MVQ44 is cut off to release the braking force. Specifically, in the hill start assistance device, when the clutch device 3 is engaged at the time of start and the braking force release condition, that is, the MVQ release condition (release point) is satisfied, the signal supplied to the solenoid valve MVQ44. Is shut off. As a result, the braking force is appropriately released, and the vehicle can be started.

By the way, in the slope start assist device according to the present invention, a plurality of the MVQ cancellation conditions are set in advance as conditions C1 to C5. Referring to FIGS.
The flowchart of the MVQ cancellation condition selection routine for selecting cancellation conditions (conditions C1 to C5) is shown. Hereinafter, the procedure for selecting the MVQ cancellation conditions (conditions C1 to C5) according to the present invention will be described with reference to the flowcharts of FIGS.

First, in step S10, the gradient sensor 9
0 is used to detect the gradient S. Then, in the next step S11, the operation state of the release point adjustment SW 92 is detected. The release point adjustment SW 92 is
This is a switch for finely adjusting the MVQ release condition as appropriate according to the driver's preference. This release point adjustment SW 92
For example, in the case where the timing of releasing the braking force is late and the vehicle retreats when starting up a slope and the driver feels a so-called slipping feeling, the driver is operated to eliminate the slipping feeling.

More specifically, the release point adjustment SW 92 is configured so that the entire MVQ release condition can be adjusted stepwise or continuously, for example, in the vicinity of a standard value, and the braking force release timing is collectively controlled in all of the conditions C1 to C5. It is made to be faster or slower. Therefore, here, the operation amount is detected. In the next step S12,
It is determined whether or not the clutch is completely connected during coasting before stopping. That is, it is determined based on the information from the clutch stroke sensor 17 whether or not the vehicle was traveling at a very low speed before stopping and the clutch device 3 was not completely connected. If the result of the determination is true (Yes) and it is determined that the clutch is fully engaged during coasting before stopping, then the process proceeds to step S13.

In step S13, the vehicle load degree αVL is calculated. The vehicle load αVL is a parameter corresponding to the weight and load of the vehicle, and is mainly a rack position signal SRC from the rack position sensor 9, engine speed information Ne from the engine rotation sensor 8, and a vehicle speed sensor 78.
Is calculated based on the vehicle speed information V from the vehicle.

More specifically, the vehicle load αVL is calculated by the following procedure (vehicle load detecting means). First, an engine torque Te is calculated from the rack position signal SRC and the engine speed information Ne from a preset map or the like, and a driving force F of the vehicle is calculated from the engine torque Te by the following equation, for example.
It is calculated from (1).

F = (Te · it · if · η) / rw (1) where it is the gear ratio of the shift stage, if is the final reduction gear ratio (differential gear ratio), η is the power transmission efficiency, rw Is the tire radius. Meanwhile, the air resistance Rl of the vehicle is calculated. Here, the air resistance Rl as the running resistance of the vehicle is calculated from the vehicle speed information V by the following equation (2).

R1 = λ · As · V ² (2) where λ is the air resistance coefficient and As is the front projected area of the vehicle. Next, from the driving force information F and the air resistance information Rl, an acceleration α0 equivalent to a straight flat road vehicle is calculated from the following equation (3). α0 = g · {F− (μW0 + Rl)} / (W0 + Wr) (3) where g is the gravitational acceleration, μ is the road surface friction coefficient, W0 is the weight of the empty vehicle, and Wr is the weight of the rotating part.

Then, the acceleration α corresponding to this straight flat road empty vehicle
The vehicle load degree αVL is calculated from the following equation (4) from 0 and the actual acceleration information α obtained from the vehicle speed information V. αVL = α0−α (4) At this time, if αVL> 0, the vehicle load is large (heavy), and if αVL <0, the vehicle load is small (light). Therefore, from the magnitude of the value of αVL,
It is possible to determine how large (or small) the vehicle load is. For example, when the number of passengers (loading weight) in the bus is large, the vehicle load αVL is very large, and the vehicle load is considerably heavy.

Thereafter, the MVQ release condition (condition C1) is determined according to the gradient degree S, the vehicle load degree αVL or the vehicle acceleration α and the operation state of the release point adjustment SW 92 obtained as described above.
To C5). FIG. 5 shows a selection map of the MVQ cancellation condition corresponding to the routine, which will be described with reference to FIG. Step S15
Then, whether the vehicle load degree αVL is equal to or more than the specified value α1,
That is, it is determined whether the vehicle load is large or small. When the determination result is false (No) and the vehicle load degree αVL is less than the specified value α1, and the vehicle load is relatively light, the process proceeds to step S18 in FIG.

In step S18, it is determined whether or not the gradient S is equal to or greater than a predetermined value (first predetermined value) S4 (for example, a road surface gradient of 20 °). If the determination result is false (No) and the gradient degree S is less than the predetermined value S4, the process proceeds to step S20 and subsequent steps. In step S20, it is determined whether or not the gradient S is equal to or greater than a predetermined value S3 (for example, equivalent to a road surface gradient of 15 °). In step S22, the gradient S is equal to or greater than a predetermined value S2 (for example, equivalent to a road surface gradient of 10 °). Step S24 determines whether or not there is
Then, it is determined whether or not the gradient degree S is equal to or greater than a predetermined value S1 (for example, a road surface gradient of 5 °).

If the determination result of step S24 is false (No), that is, if the gradient S is less than the predetermined value S1 and the road is relatively flat, the condition C1 is selected in step S26. On the other hand, if the determination result in step S24 is true (Yes) and the gradient S is equal to or more than the predetermined value S1 and less than S2, the condition C2 is selected in step S28.
If the determination result of step S22 is true (Yes) and the gradient S is equal to or more than the predetermined value S2 and less than S3, step S30 is performed.
In step S32, if the determination result in step S20 is true (Yes) and the gradient S is equal to or greater than the predetermined value S3 and less than S4, the condition C4 is selected in step S32.

The conditions C1 to C4 will be described in detail. These conditions C1 to C4 are defined based on the clutch stroke amount SCL detected by the clutch stroke sensor 17. In other words, when the vehicle starts,
As described above, the accelerator opening VA is, for example, 10% of the full opening.
%, The clutch actuator 16 is actuated assuming that the vehicle has shifted from the stopped state to the start state, and the clutch device 3 is brought into the connected state. Under these conditions C1 to C4, the clutch actuator 16
, The clutch valve stroke amount SCL reaches a predetermined value (predetermined stroke amount).
That is, the power supply to Q44 is stopped to release the braking force (first braking force release control means).

Here, the value of the clutch stroke amount SCL, which is the MVQ release condition, increases as the gradient of the slope increases, that is, as the gradient S increases from the value S1 to the value S4 (S1 <S2).
<S3 <S4) It is made larger. That is, as the gradient S is larger, the timing for releasing the braking force is delayed,
The braking force is maintained until the clutch device 3 is engaged and the driving torque can be more reliably transmitted to the driving wheel side. This makes it possible to prevent the vehicle from suddenly starting on a flat road or a slope with a small gradient by setting the release timing of the braking force relatively early to prevent the vehicle from starting suddenly on a slope with a large gradient. It is possible.

If the result of the determination in step S15 is true (Yes) and the vehicle load αVL is equal to or greater than the specified value α1 and the vehicle load is relatively large, then step S34 is executed.
Proceed to. In step S34, the gradient degree S is set to the value (first
A predetermined value (second predetermined value) S5 slightly smaller than S4
(E.g., a road surface gradient of 17 °) is determined. If the result of the determination is true (Yes), then condition C5 is selected in step S36 (see FIG. 5).
(a) area).

If the result of the determination in step S15 is false (N
o) and the determination result of step S18 is true (Yes)
Is satisfied, the condition C5 is selected in step S36 ((b) in FIG. 5).
region). By the way, when the vehicle load degree αVL is equal to or more than the specified value α1 and the gradient degree S is relatively large as equal to or more than the predetermined value S5 (for example, equivalent to a road surface gradient of 17 °) ((a) in FIG. 5). Area) or the vehicle load degree αVL is the specified value α
When the gradient degree S is as large as a predetermined value S4 (e.g., a road surface gradient of 20 °) or more even if it is less than 1 ((b) in FIG. 5).
Region), it can be determined that the vehicle load is extremely large and heavy.

Therefore, regarding the condition C5, instead of releasing the braking force based on the clutch stroke amount SCL as in the above conditions C1 to C4 for the above-described reason, a more realistic condition is based on a change in the engine rotation speed Ne. Stipulates release conditions. That is, under the condition C5, the clutch device 3 shifts to the connected state and the clutch plate 12
When the engine comes into close contact with the flywheel 10 and becomes almost completely connected (hereinafter, referred to as a half-clutch state), a load is applied to the engine 1 at that point, and as shown in FIG. In this case, a decrease in the engine speed Ne after the peak is detected, whereby it is determined that the clutch device 3 is in the half-clutch state, and the braking force is released (No. (2) braking force release control means, hereinafter referred to as peak release.

It should be noted that the decrease in the engine speed Ne is caused by the difference ΔNe (= Ne′−Ne) between the engine speed Ne ′ detected last time and the engine speed Ne detected this time being a predetermined value ΔNe1 (for example, 10 rpm). This is detected based on whether or not the above is true (see FIG. 6). If the decision result in the step S34 is false (N
If the gradient S is less than the predetermined value S5 in o), the vehicle load αVL is not considered to be a factor that causes the vehicle to retreat at the start of the slope as much as the gradient S, and in this case, the step S20 is performed. Then, the conditions C1 to C4 are selected in the same manner as in the case where the vehicle load degree αVL is less than the specified value α1. That is, the braking force is released based on the clutch stroke amount SCL (first braking force release control means).

That is, in the slope start assist device according to the present invention, as shown in FIG. 5, not only the MVQ cancellation condition is selectively set according to the gradient S, but also the concept of the vehicle load αVL is adopted. Is a predetermined value S4 (for example, road surface gradient 20
°) or more, and even when the gradient S is smaller than the predetermined value S4, the vehicle load αVL is large and is equal to or larger than the predetermined value S5 (for example, equivalent to a road surface gradient of 17 °) and smaller than the value S4. If the condition is within the range (region (a) in FIG. 5), the condition C5 with a slower release timing of the braking force is selected, and under this condition, the peak release is performed. When the clutch device 3 is in the half-clutch state, the power supply to the solenoid valve MVQ44 is stopped to release the braking force.

Accordingly, not only when the road surface is steep but also when the vehicle load is large and heavy, the braking force can be maintained satisfactorily long, and therefore, the inadvertent retreat of the vehicle when the vehicle starts on a sloping road can be prevented by the clutch plate 12. Despite wear due to deterioration over time or the like, it can always be reliably prevented, and the vehicle can be started smoothly without slipping feeling. Further, in the slope start assist device of the present invention, when condition C5 is selected in step S36, learning correction of the clutch stroke amount SCL used in conditions C1 to C4 is also performed (correction means). . That is, once the peak release is performed, the actual connection time point of the clutch can be known, and the clutch stroke amount SCL corresponding to each of the conditions C1 to C4 is determined based on the clutch stroke amount SCL detected at this time. The value is learned and corrected.

As a result, the clutch stroke amount SCL under the conditions C1 to C4 is considered to be realistic, and even if the clutch plate 12 is worn due to aging or the like, the solenoid valve MVQ44 is always controlled at an appropriate timing. The braking force can be released by stopping the energization. Therefore, not only when the road surface gradient is large but also when the road surface gradient is small, it is possible to reliably prevent the vehicle from inadvertently retreating at the time of starting on a slope and causing a feeling of slipping.

In FIG. 3, step S12
Is false (No), and it is determined that the clutch was not fully engaged during coasting before stopping, then step S14 is performed.
Proceed to. In step S14, the actual acceleration, that is, the vehicle acceleration (deceleration) α is calculated from the vehicle speed information V.

When the result of the determination in step S12 is false (No), the vehicle acceleration α is obtained instead of the vehicle load degree αVL instead of the vehicle load degree αVL during coasting before stopping, such as when the vehicle stops after starting at a very low speed. If the clutch is not completely engaged, it is based on the fact that the vehicle load degree αVL cannot be calculated accurately. Therefore, in such a case, it is determined in step S16 whether the vehicle acceleration α is equal to or less than the specified value α2, that is, whether the vehicle acceleration α is large or small instead of the vehicle load degree αVL. At this time, it can be estimated that the smaller the vehicle acceleration α, the greater the vehicle load.

If the result of the determination in step S16 is false (No) and the vehicle acceleration α is greater than the specified value α2, the flow proceeds to step S18, and the result of the determination in step S16 is true (Ye
If the vehicle acceleration α is equal to or smaller than the specified value α2 in s), the process proceeds to step S34. Thereafter, the MVQ release conditions (conditions C1 to C5) are selected as described above.

[0051]

As described above in detail, according to the slope start assist device of the first aspect of the present invention, when the grade of the road surface is large, and when the grade of the road surface is relatively large, In the case where the degree of the vehicle load is large, it is added when the vehicle is stopped when the engine rotational speed temporarily decreases and the clutch enters a half-clutch state, that is, when the clutch can reliably transmit the driving torque. Braking force can be released, and even in situations where the vehicle is likely to retreat when starting on a slope, the timing for releasing the braking force is made appropriate regardless of the wear of the clutch to ensure reliable and smooth start. It can be carried out.

Further, according to the hill start assist device of the second aspect, by the learning correction of the predetermined stroke amount, the release timing of the braking force is made appropriate even at the time of normal hill start regardless of the wear of the clutch. Also, a reliable and smooth start can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire configuration of a drive system of a vehicle including a slope start assistance device according to the present invention.

FIG. 2 is a diagram showing a connection relationship of a control unit (ECU) for a mechanical automatic transmission in FIG. 1;

FIG. 3 is a part of a flowchart showing an MVQ cancellation condition selection routine according to the present invention.

FIG. 4 is the remaining part of the flowchart showing the MVQ cancellation condition selection routine following the flowchart of FIG. 3;

FIG. 5 is an MVQ corresponding to the flowcharts of FIGS.
It is a figure showing a selection map of a cancellation condition.

FIG. 6 is a diagram illustrating a change over time of the engine rotation speed and illustrating a method of detecting a release timing at the peak release.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Diesel engine 3 Clutch device (clutch) 8 Engine rotation sensor (engine rotation speed detection means) 12 Clutch plate (clutch) 16 Clutch actuator (clutch connection / disconnection control means) 17 Clutch stroke sensor (stroke amount detection means) 31 Electro-pneumatic proportion Control valve 40 Wheel brake 42 Air master 44 Solenoid valve MVQ (braking force holding means) 50 Brake pedal 70 Accelerator pedal 72 Accelerator opening sensor 78 Vehicle speed sensor 80 Control unit for mechanical automatic transmission (EC
U) 90 Gradient sensor (gradient detecting means) 92 Release point adjustment switch

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroyuki Tanaka 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation

Claims (2)

[Claims] A clutch provided to be able to connect and disconnect a driving force transmitted from an engine to driving wheels; a clutch connection / disconnection control means for disconnecting at least the clutch when the vehicle stops and connecting the clutch when the vehicle starts moving; Stroke amount detecting means for detecting a stroke amount; braking force holding means for holding a braking force when the vehicle is stopped; vehicle load degree detecting means for detecting a degree of vehicle load; and detecting a gradient of a road surface at a vehicle stop position. Gradient detecting means, an engine rotational speed detecting means for detecting an engine rotational speed, and a stroke amount detected by the stroke amount detecting means at the time of starting the vehicle to a predetermined stroke amount set according to the gradient degree. First braking force release control means for releasing the braking force when the vehicle reaches the first position; When a gradient greater than or equal to a predetermined value is detected, or when a gradient greater than or equal to a second predetermined value smaller than the first predetermined value is detected by the gradient detector, a specified value is determined by the vehicle load detector. When the degree of the vehicle load is detected, a second braking force release control unit that releases the braking force once the engine rotation speed detection unit detects that the engine rotation speed has decreased by a predetermined amount, A slope start assist device comprising: 2. The second braking force release control means, wherein once the engine rotation speed detection means detects that the engine rotation speed has decreased by a predetermined amount, the second braking force release control means outputs the predetermined braking force by the first braking force release control means. 2. The slope start assist device according to claim 1, further comprising a correction unit for learning and correcting the stroke amount.