JP3494868B2 - Neutral control device for automatic transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutral control device for an automatic transmission, which shifts the automatic transmission to a neutral state in order to prevent creep under a predetermined condition.

[0002]

2. Description of the Related Art Generally, an automatic transmission for a vehicle is designed to transmit rotational power from an engine to a gear transmission equipped with a clutch via a hydraulic torque converter. , The vehicle speed and the accelerator opening (accelerator depression amount) are changed according to a predetermined shift pattern. The shift range of the automatic transmission includes a drive range (forward drive range), a neutral range, and the like. However, when the drive range is selected, a creep that causes the vehicle to move forward little by little occurs. This is because when the drive range is set, the gear stage of the gear transmission is set to the first speed and the engine is idling, so that some torque is transmitted to the wheel side via the torque converter. .

During actual driving, the creep phenomenon is suppressed by stepping on the foot brake while maintaining the shift range in the drive range. During this period, the load of the creep is applied to the engine, so the fuel consumption of the engine is reduced. It is inevitable that it will get worse.

Therefore, there is a technique for preventing the creep by setting the automatic transmission in the neutral state when the predetermined condition is satisfied even in the drive range.
It is proposed in Japanese Patent No. 5869, Japanese Patent Application Laid-Open No. 6-147312, and the like. The predetermined conditions in this case are:
It is usually said that the accelerator is released (fully closed), the foot brake is depressed, and the vehicle speed is detected to be substantially zero.

[0005]

By the way, when the vehicle is stopped by a red signal or the like, the brake is stepped on and the vehicle is gradually decelerated to stop. At this time, immediately before the vehicle actually stops. (About 3 m before the target stop position), that is, at a very low speed (a speed around 11 km / h),
A downshift to the lowest speed (first speed) occurs. Therefore, in a vehicle equipped with the above-mentioned creep prevention device (= neutral control device), after traveling a certain distance (about 3 m) in the first speed state, the vehicle stops and shifts to the neutral state for the first time at that stage. Will be done.

However, in reality, when the vehicle is braked gently, the section in which the vehicle is decelerated at the first speed immediately before stopping is a section in which engine braking is not expected so much. There was a problem that the saving effect weakened. In addition, the downshift to the 1st speed immediately before the stop causes the driver to feel an extra shift shock, and the shift from the 1st speed state to the neutral state after the vehicle is stationary causes the driver to shift. It also made me feel uncomfortable.

In view of the above circumstances, it is an object of the present invention to provide a neutral control device for an automatic transmission, which can further improve the fuel consumption saving effect and reduce the discomfort to the driver.

[0008]

According to the invention of claim 1, even when the shift range of the automatic transmission is set to the forward traveling range, the automatic transmission is in the neutral state when a predetermined condition is satisfied. In the neutral control device for an automatic transmission according to the above, as means for determining whether the predetermined condition is satisfied, (a) means for determining that the accelerator opening is equal to or less than a predetermined value and (b) a brake is depressed. And (c) a means for determining that it is the timing for downshifting, and (d) a means for determining that the vehicle speed is equal to or lower than a predetermined value. When it is determined that the above condition is satisfied, the automatic transmission is provided with a unit that shifts to a neutral state, and the downshift is performed.
After the downshift command is output, the
Until the engaged clutch is disengaged in the transmission.
It is characterized in that the timing is set between .

Further, in the invention of claim 2, the automatic conversion
The shift range of the speed machine is below the forward drive range including the highest speed stage.
Transition to neutral when outside shift range
It is characterized in that a means for prohibiting lines is provided . further,
According to a third aspect of the invention, the temperature of the engine cooling water is equal to or higher than a predetermined value.
When the temperature is below or when the oil temperature of the automatic transmission is below the specified value.
Provided a means to prohibit the transition to the neutral state.
It is characterized by

In the apparatus of the present invention, in order to form the neutral state, specifically, the forward clutch (the clutch that is engaged when executing forward traveling) is slid. The neutral state in this case refers to a state in which the engagement hydraulic pressure is reduced to a substantially non-engaged state in which the rotational driving force (torque) is not transmitted through the clutch and is maintained. , If the hydraulic pressure is increased even a little from this state, the torque starts to be transmitted. In other words, the hydraulic pressure is not set to zero, but is controlled to a value at which the torque starts to be transmitted when the hydraulic pressure is increased even a little. As a result, it becomes possible to follow the driver's brake operation and accelerator pedal depression operation with good responsiveness after leaving the neutral control state. In this way, instead of simply setting the hydraulic pressure to zero,
Since it is maintained at a delicate value, the oil temperature that affects the clutch engagement hydraulic pressure and the water temperature related to the oil temperature (when the oil temperature cannot be measured by a sensor, etc., it can be estimated from the water temperature) are neutral. It is added to the conditions for determining the transition to the state.

According to this device, when the vehicle is stopped by gradually decelerating by depressing the brake, the automatic transmission is operated at the timing of the downshift immediately before the vehicle actually stops, that is, the timing of the downshift to the first speed. Shifts to the neutral state. Therefore, as compared to the conventional case where the vehicle travels a certain distance in the first speed state and shifts to the neutral state for the first time when the vehicle stops, the fuel saving effect is as much as the transition to the neutral state earlier. Increase. In addition, the downshift to the 1st speed immediately before the stop causes the driver to feel an extra shift shock, and the shift from the 1st speed state to the neutral state after the vehicle is stationary causes the driver to shift. It was supposed to make me feel uncomfortable,
In the apparatus of the present invention, the neutral state is not shifted to the neutral state in the stationary state, but is shifted to the neutral state at the timing of the downshift before the stationary state, so that a slight shock given to the driver can be alleviated. Also,
By adding oil temperature and water temperature conditions as conditions for shifting to the neutral state, more stable control can be realized.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, the configuration of the neutral control device of the embodiment will be described with reference to FIG. This neutral control device has a control means 2 for issuing a command to bring an automatic transmission (strictly speaking, a gear transmission) 1 into a neutral state. The control means 2 includes a signal from the range detection means 3, a signal from the accelerator opening detection means 4, a signal from the brake operation detection means 5, a signal from the downshift detection means 6, a signal from the vehicle speed detection means 7, and a coolant temperature of the engine. The signal of the detection means 8 and the signal of the transmission oil temperature detection means 9 are input.

The control means 2 is based on these signals,
When the shift range is the forward drive range, (a) the accelerator opening is less than or equal to a predetermined value, (b) the brake pedal is depressed, (c) is the timing at which downshifting is performed, and (d) the vehicle speed is less than or equal to a predetermined value. The main condition is that the automatic transmission is set to the neutral state to prevent creep. Further, when the temperature of the engine cooling water is below a predetermined value, and when the oil temperature of the automatic transmission is below a predetermined value,
Prohibit transition to neutral state.

Next, the contents of the control performed by the control means 2 will be described with reference to the flowcharts of FIGS. 2, 3 and 4. FIG. 2 shows a flag NEU for performing neutral control.
This defines the process up to setting G, and FIG. 3 shows the details of the contents of step S2 in the process. When the process of FIG. 2 starts, it is determined in a first step S1 whether the neutral control flag NEUG is 1. If YES, this routine process is terminated and N
In the case of O, the process proceeds to step S2, and the neutral control permission determination is performed.

As shown in FIG. 3, when the routine process for determining permission is started, the current shift range is checked in step S21. That is, the shift range is D4
Or not (POS = 4?). This step S21 is provided to check the neutral control except for the D4 range, because the neutral control is not performed. That is, the shift position in which the shift such as the second speed range and the first speed range is held is selected because it is necessary for the driver to drive (engine braking etc.), and at that time, the neutral control is not performed. This is because. The D4 range in this case refers to the forward traveling range including the highest speed stage.

Further, in step S22, it is checked whether or not the oil temperature TATF of the automatic transmission is a predetermined value or more, and in step S22
In step 23, it is checked whether the engine cooling water temperature TW is equal to or higher than a predetermined value, in step S24 it is checked whether the accelerator pedal is released, and in step S25 it is checked whether the foot brake is depressed. The determination in step S24 is whether or not the current accelerator opening AP is smaller than a predetermined value APZ (a value that can substantially determine whether the accelerator pedal is fully closed) or whether a flag APZ that indicates the accelerator pedal is fully closed is set to 1. Done in. The determination in step S25 is made based on whether the flag BRK indicating the brake ON is 1 or not.

If all the conditions are YES, step S2
Proceed to 6 and shift permission flag NEU to neutral control
Make an OK. If even one of the conditions is not satisfied, the process proceeds to step S27 in order not to permit the shift to the neutral control, the neutral control shift permission flag NEUOK is reset, and the neutral control start delay timer tmNEUON is set. Predetermined memory value tmN
EUONS (for example, time of about 100 ms) is set.

The reason why the neutral control is not performed when the oil temperature condition is not OK is that the response of the automatic transmission is poor when the oil temperature is low and the controllability at the time of restarting becomes poor. . In addition, the neutral control is not performed when the water temperature condition is not OK,
This is because the idling speed is high when the water temperature is low. The neutral state in this device does not mean that the clutch hydraulic pressure is set to zero, but it is a marginal state where torque is transmitted when the hydraulic pressure is raised even slightly, that is, the driver's braking operation or accelerator pedal depression operation. In this case, it refers to a delicate state in which the vehicle can get out of the neutral state with high response. Therefore, in the case where it is an obstacle to secure such a delicate state, the oil temperature condition and the water temperature It is excluded by the judgment of the conditions.

Returning to FIG. 2, after the process of step S2, the process proceeds to step S3 to check the state of the shift permission flag NEUOK to the neutral control. Same flag NE
If UOK is standing, it means that the precondition for shifting to the neutral control has been passed, and therefore, the actual condition determination after step S4 is performed. If the flag NEUOK is not set, then in step S10, the flag NEUG indicating that the neutral control is being performed is set to zero, and the process is terminated.

In step S4, the timing at which a downshift command from 3rd speed to 1st speed or 2nd speed to 1st speed is generated is detected. This downshift command is predetermined for each shift range. For example, in the case of the D4 range,
Depending on the throttle opening (or accelerator pedal opening) and the vehicle speed, a downshift command is generated when the vehicle crosses a shift line on the downshift side (to the 1st speed operation range) in a predetermined shift map. Has become. Therefore, the current throttle opening and vehicle speed are detected,
As a result of comparison with the shift line of the shift map, a downshift command is generated. In the present embodiment, the downshift timing means that the 3rd or 2nd speed clutch that is currently engaged is disengaged by the downshift command from when the downshift command is issued. It can be arbitrarily set up to the time (when the transmission capacity is lost). For example, when a command to release the engaging force of the currently engaged clutch based on a downshift command is issued, or when there is a change in the rotational speed between the input side and the output side of the currently engaged clutch When I did it. That is, step S4 is intentionally provided because the neutral control is executed in synchronization with the timing of disengaging the clutch that has been engaged by the downshift. When the downshift timing is detected in step S4 (when the determination in step S4 is YES), the process proceeds to step S5 to check the vehicle speed at that moment. If the vehicle speed V is smaller than a predetermined value VNDOWN (for example, a value near 11 km / h at which a downshift to the first speed occurs), the process proceeds to step S6, and a flag NEUG indicating that the neutral control is being performed is set first, This routine process ends.

If it is not the downshift timing,
Alternatively, if the vehicle speed has not decreased even at the downshift timing, the process proceeds to step S7. In this step S7, it is determined whether or not the vehicle has stopped by checking whether or not the vehicle speed V has become smaller than a predetermined value VNEUN (a value near 1 km / h which can be regarded as substantially zero vehicle speed). There is. If not stopped, step S8
To the neutral control start delay timer tmN
Set a predetermined stored value tmNEUONS to EUON. If stopped, the process proceeds from step S7 to step S9, and the neutral control start delay timer t
After waiting for mNEUON to count up, the routine proceeds to step S6 described above, and a flag NEUG indicating that the neutral control is being performed is set.

The neutral control start delay timer tmNEUON is provided for the following reason. That is,
It is assumed that the vehicle is stopped and the accelerator pedal is depressed immediately. In such a case, it is desirable to avoid returning the clutch to the engaged state immediately after starting to slip. Therefore, a neutral control start is awaited until a certain stop-equivalent state is expected, and a timer is provided for that purpose.

Next, the routine shown in FIG. 4 is proceeded to. In this routine, it is determined in step S31 whether the flag NEUG indicating that the neutral control is being performed is set, and YES
In the case of, the process proceeds to the neutral control subroutine of step S32, and in the case of NO, the process proceeds to the in-gear subroutine of step S33.

In the neutral control subroutine, the clutch of the automatic transmission is released to create the neutral state. When the brake is turned off or the accelerator is depressed in the neutral state, the neutral state is stopped and the normal control is resumed.

By controlling in this way, the vehicle is already in a neutral state before the vehicle actually stops.
The fuel consumption can be reduced accordingly. Also, 3
Since the shift to the neutral state is made at the timing of the downshift from the first speed to the first speed or the second speed to the first speed, the downshift to the first speed (the establishment of the gear) does not actually occur. Also, instead of shifting to the neutral state when the vehicle is stopped, the downshift command shifts to the neutral state at the timing at which the clutch that has been engaged until now is disengaged. A slight shock given to the driver can be alleviated, and the driver will not feel discomfort. In other words, if there is a change in engine speed due to a shift to the neutral state while the vehicle is stopped, the driver will feel this change even though he or she has not operated anything. However, even if such a change occurs at the timing of the downshift when the vehicle is still moving, the driver does not feel a particular discomfort.

[0026]

As described above, according to the first aspect of the present invention, the vehicle shifts to the neutral state at the timing of the downshift immediately before the vehicle stops, so that the fuel saving effect is further improved and the driver is informed. It is possible to reduce the discomfort of. That is, the timing at which the downshift is performed
The automatic transmission after the downshift command is output.
Until the clutch in the engaged state is disengaged
Since the timing is set to
Instead of shifting to the neutral state in the
Neutral at the timing of the downshift while
A slight shock is given to the driver,
Can also be alleviated, which may make the driver feel uncomfortable.
Disappear. Further, according to the invention of claim 2, the automatic shift is performed.
The shift range of the machine is other than the forward drive range including the highest speed
Shift to the neutral state when the shift range is
Is prohibited, the driver will be
2nd speed range or 1st speed selected because rake is required
Shift position where shifts such as range are held
So you can turn off neutral control
It Further, as in the invention of claim 3 , by adding the conditions of oil temperature and water temperature as conditions for shifting to the neutral state, more stable control can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a control flowchart including steps corresponding to the respective means of FIG.

3 is a flowchart showing a subroutine of step S2 in the flowchart of FIG.

4 is a flowchart showing a routine executed after the flow of FIG.

[Explanation of symbols]

1 automatic transmission 2 control means 3 Range detection means 4 Accelerator opening detection means 5 Brake operation detection means 6 Downshift detection means 7 Vehicle speed detection means 8 Engine cooling water temperature detection means 9 Automatic transmission oil temperature detection means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F16H 59:72 F16H 59:72 59:78 59:78 (56) References JP-A-59-19764 (JP, A) JP Flat 11-159610 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16H 59/00-63/48

Claims (3)

(57) [Claims] 1. A neutral control device for an automatic transmission that brings the automatic transmission into a neutral state when a predetermined condition is satisfied even when the shift range of the automatic transmission is set to a forward drive range, As means for judging whether the predetermined condition is satisfied, (a) means for judging that the accelerator opening is equal to or smaller than a predetermined value, (b) means for judging that the brake is depressed, and (c) downshifting. And (d) a means for determining that the vehicle speed is less than or equal to a predetermined value, and when all of these determining means determine that the conditions are met,
A means for shifting the automatic transmission to a neutral state is provided , and the timing for performing the downshift is the downshift.
Of the automatic transmission, after the
Timing until the engaged clutch is disengaged
A neutral control device for automatic transmissions, which is characterized by being set to 2. The shift range of the automatic transmission is the highest speed
When the shift range is other than the forward drive range including gears
Has a means to prohibit the transition to the neutral state.
The neutral of the automatic transmission according to claim 1, wherein
Control device. 3. The temperature of engine cooling water is below a predetermined value.
Or when the oil temperature of the automatic transmission is below a specified value,
Providing means to prohibit transition to neutral state
Automatic shift according to claim 1 or 2, characterized in that
Neutral control device of the machine.