JPS61220940A - Prevention of engine stop for automatic transmission - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention electronically controls a friction clutch interposed between an engine and a transmission via an actuator, and also changes the gear position of the transmission. The present invention relates to a method for preventing engine stop of an automatic transmission that is electronically controlled via means.

<Conventional technology> In recent years, automatic transmission devices that can automatically select the gear position according to the driving conditions of the vehicle have been developed in order to reduce the burden of driving operations on the driver of large freight vehicles, passenger cars, etc. It is considered.

Conventional automatic transmissions are aimed exclusively at small passenger cars, and are equipped with a fluid coupling such as a torque converter between the engine and the planetary gear transmission, using pressure oil as the control medium. A type of transmission equipped with gear position switching means is common.

<Problems to be solved by the invention> In developing automatic transmission devices for large freight vehicles, etc., it is important to avoid expensive torque converters, etc., since the number of vehicles produced is significantly smaller than that of passenger cars. A new design would be extremely disadvantageous in terms of cost, and it is desirable to use existing drive systems such as friction clutches and transmissions as they are, including existing production equipment.

Based on this knowledge, it is an object of the present invention to provide an automatic transmission device that can automatically achieve smooth gear shifting operations through electronic control using a conventional drive system as is, and furthermore, to provide a method for preventing engine stoppage. It is said that

Means for Solving Problems> The speed change control method for an automatic transmission according to the present invention includes a clutch actuator for operating a friction clutch connected to an output shaft of an engine, and a friction clutch connected to an output shaft of an engine. a gear-type transmission to which the input shaft is connected; a gear-position switching means for switching the gear position of the gear-type transmission; and the clutch actuator and the gear-position switching means based on the driver's intention and vehicle running conditions. In the automatic transmission device, the friction clutch is disengaged when the engine speed is below a predetermined engine stop prevention speed to prevent engine stop, and the friction clutch is disengaged when the engine speed is below a predetermined engine stop prevention speed. The engine is characterized in that the engine stop prevention rotation speed when the accelerator is not depressed is set higher than the engine stop prevention rotation speed when the accelerator is depressed during normal driving and when starting.

<Operation> [1 clutch is operated by the control device via the clutch actuator, and the transmission of driving force from the engine to the gear type transmission is interrupted. Further, the control device controls the operating characteristics of the clutch actuator to transmit the driving force with less shift shock, and the control device operates the gear position switching means in conjunction with the operation of the friction clutch.
The optimal gear position is automatically selected. This gear change operation is performed based on the driver's will and preset vehicle driving conditions.

On the other hand, to prevent the engine from stopping, the friction clutch is disengaged at a relatively high engine speed when the accelerator is not depressed during normal driving, and the friction clutch is prevented from starting when the friction clutch is disengaged. When the accelerator is depressed, the friction clutch remains connected even at low engine speeds, allowing for smooth driving. Also, when starting, the friction clutch remains connected even at low engine speeds, regardless of whether the accelerator is depressed.
A smooth start is performed.

Embodiment As shown in FIG. 1, which shows the concept of an embodiment of an automatic transmission that implements the method of the present invention, this automatic transmission has a diesel engine (hereinafter simply referred to as engine) 30 and its output power. It is attached across a gear type transmission 32 that receives the rotational force of the shaft 30a via a friction clutch 31.

The engine 30 has a fuel injection pump (
An accelerator pedal 37 and an electromagnetic actuator 38 are connected to the control rack 35 of the pump 34 via a link 36, and an electromagnetic actuator 38 is connected to the input shaft 33. An engine rotation sensor 39 is attached that generates a rotation speed signal of the output shaft 30a of the engine 30. Friction clutch 31
The clutch plate 41 is brought into pressure contact with the flywheel 40 by a well-known clamping means (not shown), and when the air cylinder 42 as a clutch actuator shifts from a non-operating state to an operating state, the clamping means operates in the releasing direction, The clutch 31 changes from a connected state to a disconnected state (FIG. 1 shows the disconnected state). It should be noted that this clutch 31 has a disconnection state or an ON state of the clutch 31.
10 FF Clutch air sensor 7 detected by F operation
0 is attached, but a clutch touch sensor 43 may be attached instead. Further, a clutch rotation speed sensor 45 is attached to the input shaft 44 of the gear type transmission 32 to generate a signal of the rotation speed of the input shaft 44 (hereinafter referred to as clutch rotation speed). Air chamber 46 of air cylinder 42
An air passage 47 is connected to the air passage 47, which is connected to an air tank 48 as a high-pressure air source.

An electromagnetic cut valve 49 is installed in the middle of the air passage 47 as an opening/closing means for controlling the supply of working air, and a duty-controlled normally closed electromagnetic valve 50 is also provided to open the air chamber 46 to the atmosphere. is installed. The air cylinder 42 is equipped with the aforementioned clutch air sensor 70 that outputs an ON signal when the internal air pressure exceeds a specified value that causes the clutch 31 to be disengaged, and the air tank 48 is further equipped with the clutch air sensor 70 that outputs an ON signal when the internal air pressure exceeds a specified value that causes the clutch 31 to be disengaged. An air sensor 72 is attached that outputs an ON signal when the condition is reached. To change the gear position of the gear type transmission 32 that achieves each gear, the driver operates the change lever 54 to a gear position corresponding to a shift pattern as shown in FIG. 2, for example. A gear shift unit 51 as gear position switching means is operated based on a gear shift signal obtained by switching the selection switch 55, and the gear position is switched to a target gear position corresponding to the shift pattern. Here, R indicates reverse gear, N is neutral, 1.2.3
indicates each designated gear.

Hemorrhoids indicates any automatic gear from 2nd to 7th gear, and when DP, D, and Range are selected, 2nd to 7th gears will be automatically changed based on the vehicle driving conditions by the optimum gear determination process described later. determined.

In addition, as shown in FIG. 3, the shift range between DP, which is a powerful automatic gear, and D5, which is an economy automatic gear, is shown in FIG. The timing is set on the higher speed side for the D2 range to cope with times when the vehicle is under high load.

The gear shift unit 51 is a control unit 5
A plurality of solenoid valves (the first
) 53 (only one is shown in the figure) and these solenoid valves 53
and a pair of power cylinders (not shown) to which high-pressure working air is supplied from the air tank 48 to operate the select fork and shift fork (not shown) of the gear type transmission 32, and an actuation signal given to the electromagnetic valve 53. The power cylinders are respectively operated to change the meshing mode of the gear type transmission 32 in the order of select and shift. Further, the gear shift unit 51 is provided with gear position switches 56 as gear position sensors for detecting the positions of each gear, and gear position signals from these gear position switches 56 are output to the control unit 52.

Further, a vehicle speed sensor 58 is attached to the output shaft 57 of the gear type transmission 32 and outputs a vehicle speed signal.
An accelerator load sensor 60 is attached to the accelerator load sensor 60, which generates a resistance change according to the amount of depression as a voltage value, converts this into a digital signal by an A/D converter 59, and outputs it.

A brake sensor 62 is attached to the brake pedal 61, which outputs a brake signal at a high level when the brake pedal 61 is depressed.
A starter 63 that starts the engine 30 by meshing with a ring gear on the outer periphery of the engine 30 at a proper time is attached, and its starter relay 64 is connected to the control unit 52. In addition, the reference numeral 65 in the figure indicates a microcomputer that is attached to the vehicle separately from the control unit 52 and performs various controls of the vehicle, and controls the drive of the engine 30 in response to input signals from various sensors (not shown). etc. This microcomputer 65 gives an activation signal to the electromagnetic actuator 38 of the injection pump 34, and the rotational speed of the output shaft 30a of the engine 30 (
Hereinafter, this will be referred to as engine rotation speed).However, the output signal as an engine rotation increase/decrease signal from the control unit 52 should be received with priority over the amount of depression of the accelerator pedal 37 via the link 36. The engine speed is increased or decreased according to this output signal.

The control unit 52 is a microcomputer dedicated to the automatic transmission, and is composed of a microprocessor (hereinafter referred to as CPU) 66, a memory 67, and an interface 68 as an input signal processing circuit.

The input port 69 of the interface 68 has the above-mentioned gear selection switch 55, brake sensor 62, accelerator load sensor 60, engine rotation sensor 39, clutch rotation speed sensor 45, gear position switch 56, vehicle speed sensor 58, and clutch touch sensor 43. (tI [used when the clutch air sensor 70 detects the disconnected state or connected state of the clutch 31), the clutch air sensor 70, and the air sensor 7z output signals are input. On the other hand, the output port 74 is connected to the above-mentioned microcomputer 65, starter relay 64, and solenoid valve 50.53.
and the cut valve 49, respectively, and output signals can be sent to these. In addition, the code 75 in the figure is the air tank 4.
8 is an air warning lamp that lights up upon receiving an output from a drive circuit (not shown) when the air pressure does not reach a set value, and 76 is an air warning lamp that receives an output when the wear amount of the friction clutch 31 exceeds a specified value. This is the clutch warning lamp that lights up.

The memory 67 is a read-only ROM in which programs and data shown in flowcharts in FIGS. 5 to 9 are written.
It consists of a RAM that can be used for both reading and writing. That is,
In addition to the above program, the duty rate a of the solenoid valve 50 corresponding to the value of the accelerator load signal is previously stored in the ROM as a map as shown in FIG. read out. The gear selection switch 55 described above outputs a select signal and a shift signal as a gear change signal, but the gear position corresponding to a pair of combinations of these signals is stored in advance as a data map, and the select signal and shift signal are stored in advance. When receiving the map, the corresponding output signal is outputted to each solenoid valve 53 of the gear shift unit 51 with reference to this map, and the gear position is adjusted to the target gear position corresponding to the gear shift signal.

In this case, the gear position signal from the gear position switch 56 is output when the gear shift is completed, and it is determined whether all gear position signals corresponding to the select signal and shift signal have been output, and a signal indicating whether the meshing is normal or abnormal is determined. It is used to emit. Furthermore, the ROM also stores a map for determining the optimum gear position based on vehicle speed, accelerator load, and engine rotation signals when a target gear position exists in the range or hemorrhoid range.

Here, the speed change control procedure of this embodiment will be explained based on FIGS. 5 to 9.

As shown in FIG. 5, when the program starts, the control unit 52 enters the start process, and after the start process is completed, inputs a vehicle speed signal, and sets the value to a specified value (for example, 0).
kn7h to 3kIll/h), a start process is performed, and when the value is above a specified value, a shift process is performed.

In the starting process shown in FIG. 6, a signal of the engine rotation speed Nt is input, and it is determined whether the value is within the stop range of the engine 30. If the engine 30 is stopped, a clutch connection signal is output and a time lag is detected. , and the friction clutch 31 is connected at the normal pressure and in the normal state.

When the friction clutch 31 is connected at the normal pressure and in the normal state, the friction clutch 31 is disengaged to some extent from this position and the drive wheels of the vehicle shift from the rotating state to the stopped state (hereinafter referred to as the half-clutch state position). (denoted as a point) is corrected depending on the wear condition of the facing of the friction clutch 31, the presence or absence of a loaded object, etc. In other words, from LE point to friction clutch 3
The stroke of the clutch plate 41 until the clutch plate 1 is completely engaged is always approximately constant, and the friction clutch 31 is smoothly engaged regardless of the state of the vehicle. When the LE point is corrected, it is determined whether the position of the change lever 54 and the gear position are the same, that is, the shift signal and the gear position signal are the same and the target gear (
D.E.

When the Dp range is selected, it is determined whether or not the gear positions of the gear type transmission 32 are aligned (preset to 2nd speed, for example). If the position of the change lever 54 and the gear position are different, it is determined whether the air in the main air tank 48 has reached a specified pressure, and if the pressure has been reached, the friction clutch 31 is activated. Then, the air in the air tank 48 is used to operate an actuator (not shown) to automatically align the gear position with the position of the change lever 54, connect the friction clutch 31, and connect the air tank 48 (main tank) to the sub tank (not shown). After turning off the switching solenoid valve, it is again determined whether the position of the change lever 54 and the gear position are the same.

If the air in the air tank 48 has not reached the specified pressure, it is determined whether the air in the sub-tank has reached the specified pressure, and if the air has reached the specified pressure, the switching solenoid valve is turned on. Then, the friction clutch 31 is disengaged, and the power cylinder is actuated with the air in the sub-tank to automatically select the gear position corresponding to the position of the change lever 54. If the air in the sub-tank has not reached the specified pressure, the air warning lamp 75 is lit and the driver is instructed to
8 and the air in the sub tank is below the specified pressure. On the other hand, if the position of the change lever 54 and the gear position are the same, a relay for enabling starter is output. When the starter enable relay is output, the starter 63 can be started and the engine 30 can be started, so the engine 3
0 is activated, and if the engine 30 starts, turn off the starter enable relay, and if the engine 30 does not start, check whether the change lever 54 position and gear position are the same again. to judge. When the starter enable relay is turned OFF, it is checked whether the air in the air tank 48 and sub-tank has reached the specified pressure, and if the air has not reached the specified pressure, the air warning lamp 75 is turned on and the air is The judgment is repeated until the pressure reaches the specified pressure, and when the pressure reaches the specified pressure, the air warning lamp 75 is turned off and the starting process is completed.

After the start process is completed, the vehicle speed signal is read, and if it is below a specified value, the start process begins.

As shown in Figure 7) and (b), the CPU 66 first
An ON signal is output to the cut valve 49 to disengage the swA clutch 31, and the friction clutch 31 is disengaged. Next, it is determined whether the position of the change lever 54 and the gear position are the same, and if NO, the gear position is adjusted to the target gear position. When the position of the change lever 54 becomes the same as the gear position, it is again determined whether the vehicle speed is smaller than the specified value, and if the vehicle speed is higher than the specified value (NO), an accelerator load signal (described later) is sent. amount) Proceed to the detection step.

On the other hand, if this is not the case, the shift signal is used to read whether the next gear position that has reached the target gear position is neutral or not.
In the case of ES, LE point correction is performed again. If the gear position is other than neutral (NO), the friction clutch 31 is connected to the LE point. Next, it is determined whether or not the accelerator load signal value exceeds a specified value (voltage low enough to indicate the driver's intention to start), and if No, indicating that the driver has no intention to start, each of the steps described above is performed. Repeat. On the other hand, if the answer is YES, indicating that there is an intention to start, the process proceeds to the next step, where the accelerator load signal value is detected, and the optimum duty rate α corresponding to this value is read from the map shown in FIG. Then, the pulse signal with the obtained optimum duty rate α is output to the solenoid valve 50, and the clutch 31 is gradually connected. At this point, the CPU 66 outputs a selection signal to the input port 69 to continue inputting the signal of the engine speed N, and the memory 67 stores ε engine speed E number N over time based on the signal of the engine speed N. The engine rotation speed and clutch rotation speed NcL are sequentially stored in the internal RAM.
As shown in FIG. 10, which shows an example of the change in , arithmetic processing is performed to find the peak point M, and until the peak point M is detected, the process goes to NO and repeats from the accelerator load signal detection step. On the other hand, when the peak point M is detected, the solenoid valve 50 is held ON from time B (T1). Note that the peak point M is when the output shaft 30a of the engine 30 is connected to the friction clutch 3.
This occurs because power begins to be transmitted to the driving wheels as the rotation of the input shaft 44 of the gear type transmission 32 via the gear transmission 32.

Next, the LEOFF routine is executed.

This LEOFF routine is used to deal with cases where the vehicle is slightly moved with the clutch in a partially engaged state rather than a normal start.In the LEOFF routine, it is first determined whether the vehicle speed is greater than a specified value; If YES, it is determined that it is a normal start, and the LEOFF routine ends and returns to the start flow. On the other hand, in the case of NO, it is next determined whether or not the accelerator pedal 37 is depressed, and in the case of YES, the LEOFF routine ends in the same way, and in the case of No, the LEOFF routine continues until the LE point is reached. The friction clutch 31 is disengaged. Meanwhile, it is also determined whether or not the accelerator pedal 37 is depressed, and when the accelerator pedal 37 is depressed, the process returns to the aforementioned accelerator load signal detection step. or,
After the friction clutch 31 has retreated to the LE point, the process returns to the step of determining the position of the change lever 54 and the gear position described above.

When the LEOFF routine is completed and it is determined that a normal start has occurred, the friction clutch 31 is connected from the half-clutch state at the LE point to clutch engagement, but at this time, the engine speed N after passing the peak point M is The clutch rotation speed N corresponds to the rotation of the input shaft 44 of the gear type transmission 32. Considering that the engine speed decreases gradually as L increases, control is performed so that the rate of decrease in engine speed NEf falls within a predetermined range and the gear shift becomes small. That is, first, it is determined whether the engine speed reduction rate ΔNE for each predetermined period of time is less than or equal to the first set value 1x, 1 shown in FIG. If YES, after executing the above-mentioned LEOFF routine, the accelerator load signal is detected again, the optimum duty rate α corresponding to this value is determined, and the am clutch 31 is gradually connected according to the duty rate a. After this, the engine speed reduction rate ΔN6 becomes the second set value lx, I (IX, l < I
X21) Determine whether or not it is less than or equal to
Return to before the EOFF routine and check the engine speed reduction rate Δ
Repeat the loop that keeps N constant.

On the other hand, the engine speed reduction rate ΔN6 is 1. , l, it is determined whether this engine speed reduction rate ΔNl: is greater than or equal to a third set value 1y21 (1x21 < 1y21). If YES here, the LEOFF routine is executed, and then the friction clutch 31 is gradually disengaged by off-duty. Thereafter, it is determined whether the engine speed reduction rate Δm is equal to or less than the fourth set value 1y11 (Iyll < 1y21), and if NO, the loop of disconnecting the friction clutch 31 is repeated. In the case of YES, or in the case of No in the step of determining whether the engine speed decrease rate ΔT is less than or equal to 1y21, the engine speed decrease rate ΔN
5 is I! YES in the step of determining whether it is 21 or more
In the case of , at this point, the engine speed reduction rate ΔN falls approximately within the shaded area in FIG. Therefore, conditions have been established for switching the giI friction clutch 31 to the engaged state without causing a shift shock in the half-clutch state, and without prolonging the shift time excessively. Hold on. After this,
The CPU 66 determines the engine speed NE and the clutch speed Nc.
The difference from L is a specified value (for example, IN −N l =10 r
pm) or less ε CL or not, and if NO, the above-mentioned loop is repeated, and after a predetermined time lag at T2, which is the time of YES, the solenoid valve 50 is fully opened and the clutch is engaged. I do. After this, after a predetermined time lag on the condition that the engine speed is equal to or higher than the idle speed, C
The PU66 calculates the slip rate of the friction clutch 31 (difference between engine rotation speed N and clutch rotation speed NcL/engine rotation speed N-), compares this value with a specified value, and returns to the main flow if it is less than the specified value. On the other hand, when the slip rate is above the specified value, it is determined that the amount of wear on the friction clutch 31 is large, and an ON signal as a clutch wear signal is sent to the clutch warning lamp 76 at the output port 7.
4 and a drive circuit (not shown), and the clutch warning lamp 76 is turned on.

After the starting process is completed, the CPU 66 reads the vehicle speed signal and, if the signal exceeds a specified value, starts the speed change process. Figure 8 (
al, (as shown in bl, first input boat 69
A selection signal is given to the brake to check whether the brake has failed or not. If YES indicates that there is a brake failure, downshifting is performed one gear at a time to stop the vehicle as described later. on the other hand,
If the brake fail is NO, it is checked using an acceleration sensor, for example, whether or not sudden braking is being applied with deceleration exceeding a certain value. Since it will take a long time, return to the main flow and temporarily block the gear shifting operation. However, if the friction clutch 31 is disengaged even when the brake is applied suddenly, it will be determined that the gear shift is in progress, so the gear shift operation is completed and the friction clutch 31 is connected.

On the other hand, when there is no sudden braking operation or when the friction clutch 31 is disengaged as described above even during sudden braking, the position of the change lever 54 is read and this is set to D.
Identification of designated gears 1, 2, and 3 other than P and ζ, D
Determine whether it is an E automatic gear, an R gear, or an N gear.

1. In the case of designated gears 2 and 3, the change lever 54
It is determined whether or not the position of and the gear position are the same, and if YES, return to the main flow, and if NO, proceed to the next step. In this step, the change lever 54 is positioned at one of the target gears 1, 2.3, and the current gear position before shifting is in the DE range, which corresponds to a downshift from there. Determine whether or not. If YES, it is determined whether the downshift can be performed without overrunning the rotation of the engine 30, and if NO, proceeding to the next step and warning the driver of the overrun with a reverse warning buzzer. Return to the main flow without changing gears.

If the determination as to whether or not there is an overrun is YES, a downshift operation is performed by one gear from the current gear position as follows. As shown in FIG. 12, which shows the operational concept of this downshift operation, the ilJ m 4R of the engine rack 35 is output to the electromagnetic actuator 38 via the output boat 74 and the microcomputer 65, and the engine speed Nt is maintained as it is. Hold in this state. Then, an ON signal is output to the cut valve 49 for a predetermined period of time via the output port 74 to disengage the friction clutch 31, and a control signal is output to each electromagnetic valve 53 of the gear shift unit 51 so that the gear position is one gear higher than the gear position before shifting. Perform a downshift to the lower gear position. Next, the electromagnetic actuator 38 is connected via the output port 74 and the microcomputer 65.
The clutch rotation speed N increases the engine rotation speed NE.

A voltage signal that causes the same rotation as L is output as an accelerator pseudo signal, and the clutch rotation speed N after shifting. L and engine rotational speed are made to match, air is removed from the air cylinder 42, and the friction clutch 31 is moved to a half-clutch state at the LE point. Next, the T111 friction clutch 31 is connected at the optimum duty rate α corresponding to the accelerator load signal, and the difference between the engine rotation speed N and the clutch rotation speed N is compared with a specified value set in advance for each gear. IN
,-N. The operation of connecting the friction clutch 31 at the duty rate α is repeated until Ll becomes equal to or less than the specified value.

Then, after lN-N1 becomes less than the specified value, a clutch connection signal is output and W is turned on after a predetermined time lag.
Ii, the engagement of the friction clutch 31 is completed, the accelerator pseudo signal is released, and the process returns to the main flow. If the clutch rotational speed N exceeds the specified value in the above operation, it is assumed that the friction clutch 31 is worn out, and the friction clutch 31 is not connected and the glue connector shown in FIG. Proceed to LE point correction.

On the other hand, if the result of the determination as to whether or not this corresponds to a downshift from the Dp, D, range is NO, a determination is made as to whether or not it is a shift up. If the answer is YES, a shift-up operation is performed as follows, and the process returns to the main flow. As shown in FIG. 13, which shows the operational concept of this shift-up operation, a control signal for the control rack 35 is output to the electromagnetic actuator 38 via the output port 74 and the microcomputer 65, and the engine speed N is set to idle. Return to rotation. After disengaging the friction clutch 31, the gear position is outputted to each electromagnetic valve 53 via the output port 74 so as to match the target gear position, which is one of 1.2.3 as the designated gear position. do. Thereafter, the operation after outputting the accelerator pseudo signal of the downshift operation is performed to obtain the clutch rotation speed N after the gear shift. The engine rotation speed is made to match L, the friction clutch 31 is completely connected, and the process returns to the main flow. If the result of the above judgment on whether or not to shift up is NO, it is judged whether or not the overrun is within the range, and when it is YES, the engine rotation speed is held at the same state and the friction clutch is 31 and change the gear position to the specified gear 1, 2.
3, perform the operations after outputting the accelerator pseudo signal of the downshift operation, and return to the main flow. Also, the result of the determination as to whether or not the above-mentioned overrun is within the range is N.

If so, a warning will be issued by a warning buzzer.

The above operation is performed when the result of the determination of the position of the change lever 54 is the designated gear stage of 1, 2.3, but the result of the determination of the position of the change lever 54 is DP, D. , the following operations are performed. That is, it detects the vehicle speed and the amount of depression of the accelerator pedal 37, determines whether the change lever 54 is in the D2 range or the hemorrhoid range, and selects each of the hemorrhoids or hemorrhoids from a preset map as shown in FIG. Determine the optimum gear position to be considered as the target gear position in the range. After this, it is determined whether the gear position matches the optimum gear position, and if YES, the process returns to the main flow, and if NO, the process moves to the step of determining whether to upshift or not, and the same shift as described above is performed. An operation is performed.

Further, if the result of the determination of the position of the change lever 54 is R gear, the CPU 66 determines whether or not the gear position matches R gear as the target gear, and selects YES if reverse operation is currently in progress. If the answer is No, which is an erroneous operation, the engine speed is set to N idle rotation and the friction clutch 31 is disengaged in the same manner as described above. Then, in order to return the gear position to neutral, an output is sent to each electromagnetic valve 53 via the output port 74, and after lighting a reverse warning lamp that indicates a gear shift error,
The friction clutch 31 is connected and the process returns to the main flow.

Furthermore, if the result of the determination of the position of the gear shift lever 54 is N gear, it is determined whether or not the change lever 54 has moved within a predetermined time, that is, the N gear is passed during the shift operation by the driver. Determine whether or not you have done just that. If the result of this judgment is YES in the middle of a gear shift operation, the position of the change lever 54 and the gear position are judged as described above, and then the control returns to the main flow or shifts up or shifts down. The user then performs an operation to return to the main flow. However, when N stages are selected, N
In the case of o, the engine speed Nl: is lowered to idling speed, the lI friction clutch 31 is disengaged to set the gear position to neutral, and then the friction clutch 31 is connected again to return to the main flow.

On the other hand, an engine rotation calculation routine as shown in FIG. 9 is executed at an appropriate position in the above-described flow. In FIG. 9, first, whether or not the engine is stopped is determined from both the engine rotation speed N5 and the oil pump 3.
In other words, the engine speed NE is the specified value (value close to zero)
A determination is made as to whether or not the oil pump is below the specified value, and if the oil pump is stopped, it is then determined whether or not the oil pump is stopped, and if the oil pump is stopped, it is assumed that the engine is stopped and the process proceeds to the glue connector in FIG. On the other hand, if the oil pump is not stopped or if the engine speed N exceeds the specified value, then it is determined whether or not a start process is currently in progress.

When the vehicle is not starting, that is, when driving in general, it is determined whether the accelerator is depressed. Here, if the amount of accelerator depression that is determined to be that the accelerator is not depressed is less than the specified value, the engine rotation speed NE
and the preset first engine stop prevention rotation speed N
ESTi, and if the engine speed N6 is less than the first engine stop prevention speed 'ESTI, the friction clutch 31 is disengaged and the process proceeds to the glue connector in FIG. Engine stop prevention rotation speed N
If STI exceeds STI, the engine rotation calculation routine ends. On the other hand, when the accelerator is depressed, that is, when the amount of accelerator depression exceeds the specified value, a second engine stop prevention rotation speed NE6 set higher than the first engine stop prevention rotation speed Nes□□ is set.
Compare T□ and engine speed N, and find engine speed N.
, is the second engine stop prevention rotation speed N! ! If it is less than i72, the friction clutch 31 is similarly disengaged, and if the engine speed NE exceeds it, the engine speed calculation routine ends. If the start process is currently in progress, the engine speed NE is compared with the first engine stop prevention speed NESTl regardless of whether the accelerator is depressed, and the same operation is performed.

That is, in order to prevent engine stop, the friction clutch 31 is disengaged when the engine speed NE is below a predetermined engine stop prevention rotation, but engine stop is prevented when the accelerator is not depressed during normal driving. The rotational speed is set higher than the engine stop prevention rotational speed when the accelerator is depressed during normal driving and when starting. In this embodiment, the first engine stop prevention rotation speed N is set to 300 rpm, where there is a possibility of engine stop, and the second engine stop prevention rotation speed N is set to 600 rpm, which is close to the engine idle εST2 rotation speed. The set engine stop prevention rotation speeds are as shown in Table 1, depending on whether the vehicle is starting, when driving in general, and whether or not the accelerator is depressed.

Table 1 Engine stop prevention rotation speed If you do this, during normal driving, when the accelerator is not depressed, the friction clutch 31 will be disengaged at a relatively high engine rotation speed N, so when the friction clutch 31 is disengaged at low engine speeds. It is possible to prevent the shock caused by the engine reverse torque that occurs when the accelerator is pressed, and when the accelerator is depressed, the engine speed N decreases due to an increase in load, etc.
Friction clutch 31 up to low rotational speed even when E decreases
Since the connection is maintained, stable operation is possible.

On the other hand, when starting, the GIIM clutch 31 is always connected to a low engine speed regardless of whether the accelerator is depressed, so even if the driver turns on or off the accelerator when starting, smooth starting is possible regardless of whether the driver presses the accelerator on or off. It becomes possible.

In addition, in this embodiment described above, the air pressure from the air tank 48 installed in the vehicle is used to drive the air cylinder 42 for operating the friction clutch 31, but it is of course possible to use hydraulic pressure as the control medium. be. However, in this case, a new hydraulic pressure generation source such as an oil pump must be added, which may increase costs. Furthermore, it goes without saying that the speed change control procedure, shift pattern, etc. shown in this embodiment can be modified in detail as necessary.
The present invention can also be applied to vehicles equipped with gasoline engines. Furthermore, a dummy clutch pedal may be installed for the driver who is switching from a manual transmission, and in this case, the clutch pedal functions in priority over the air cylinder 42 in the R gear and the designated gears of 1 and 2.3. It is also possible to set it so that

<Effects of the Invention> According to the speed change control method for an automatic transmission of the present invention, a drive system such as a general friction clutch or gear type transmission is used as is, and air from an air tank installed in the vehicle is used as a control medium to control the friction clutch. Since the actuator and the power cylinder of the gear position switching means are actuated to perform the gear shift operation, a low-cost automatic transmission device can be obtained without significantly improving conventional vehicle production equipment.

Furthermore, since the friction clutch is automatically disengaged when the engine speed is less than the predetermined engine stop prevention rotation speed, it is possible to prevent the engine from being inadvertently stopped, and the shock caused when the friction clutch is disengaged is prevented, resulting in a smooth start. This has the advantage of allowing for flexible driving.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an automatic transmission according to an embodiment of the present invention, Fig. 2 is a conceptual diagram showing an example of its shift pattern, and Fig. 3 is an example of its shift characteristics between the DP range and the range. Figure 4 is a graph representing an example of a map for determining the duty rate, Figures 5 to 9 are flowcharts representing an example of the control program, and Figure 10 is the engine rotation speed at the time of the shift. FIG. 11 is a graph showing an example of the change rate of engine speed during gear shifting, FIG. 12 is a conceptual diagram of the operation during a downshift operation, and FIG. FIG. 3 is a conceptual diagram of the operation during a shift-up operation. In the drawing, 30 is the engine, 30a is the output shaft of the engine, 31 is the lE clutch, 32 is the gear type transmission, 34 is the fuel injection pump, 35 is the control rack, 37 is the accelerator pedal, 38 is the electromagnetic actuator, 42 is an air cylinder, 44 is an input shaft of a gear type transmission, 48 is an air tank, 50 is a solenoid valve, 51 is a gear shift unit, 52 is a control unit, 54 is a change lever, and 65 is a microcomputer. Figure 2 Figure 5-4 Figure 1 - DE range low - Vehicle speed - High speed Figure 5 Figure 8 (0) Figure 9 Figure 101 Me Time 11 Figure 1 Ceremony Procedures Amendment August 30, 1985 Day

Claims (1)

[Claims] A friction clutch that connects to the output shaft of the engine, a clutch actuator that operates the friction clutch, a gear type transmission that connects the input shaft to the friction clutch, and a gear position switch that changes the gear position of the gear type transmission. and a control device for controlling the operation of the clutch actuator and the gear position switching means based on the driver's will and the vehicle running conditions, the automatic transmission is configured to control the engine rotation to prevent engine stop. The friction clutch is disengaged when the engine stop prevention rotation speed is less than a predetermined engine stop prevention rotation speed, and the engine stop prevention rotation speed when the accelerator is not depressed during normal driving is changed when the accelerator is depressed during normal driving. An engine stop prevention method characterized in that the engine stop prevention rotation speed is set higher than the engine stop prevention rotation speed when the engine is stopped and when the engine is started.