JP3353390B2 - Transmission 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 driving conditions (downhills, etc.).
The present invention relates to a shift control device for an automatic transmission for automatically detecting engine speed and automatically applying an engine brake.

[0002]

2. Description of the Related Art Conventionally, as a control device for a continuously variable transmission of this type, for example, a control device disclosed in Japanese Patent Application Laid-Open No. 62-122834 is known.

[0003] According to this conventional source, when the deceleration is large (that is, at the time of sudden braking), a gear shift on the side of a larger gear ratio is commanded than at the normal case, so that the engine braking effect without a sense of incongruity during sudden braking is provided. What you get is shown.

Further, as a control device for a continuously variable transmission of this type, for example, a control device disclosed in Japanese Patent Application Laid-Open No. Sho 59-219557 is known.

[0005] According to this conventional source, a control is performed to adjust the speed ratio of the continuously variable transmission so that the speed of the vehicle is kept constant when the vehicle is running with the engine brake, so that the engine brake of the vehicle at the time of descent, etc. is performed. An example in which a complicated brake operation is eliminated in a running state is shown.

[0006]

However, in the former control device for a continuously variable transmission, control is performed such that when the vehicle deceleration is large, the engine braking force is increased. In addition, the driving wheels are easily locked by the engine braking force, and the drivability is impaired.

Further, in the latter control device for a continuously variable transmission, since the engine braking force is controlled to increase or decrease so that the vehicle speed becomes a target value, the engine exceeds the friction coefficient between the tire and the road surface. When the braking force is increased, the engine braking force is reduced after the vehicle speed is reduced by the driving wheel lock, so that the temporary driving wheel lock is permitted and driving performance is impaired. Furthermore, when the road surface friction coefficient is low, even if the engine braking force is weakened afterwards, the lock of the drive wheels is not restored again, and the drivability is impaired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an automatic transmission having a stepless motor.
In a shift control device for an automatic transmission that is a continuously variable transmission that automatically controls a speed ratio, it is an object to surely prevent a drive wheel lock that impairs drivability during traveling in which engine brake control is performed.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, a shift control device for an automatic transmission according to the present invention comprises: The more the drive wheels tend to lock, the more eyes
A means for performing control to reduce the engine speed by correcting the target gear ratio to a small value .

That is, as shown in the claim correspondence diagram of FIG. 1, a continuously variable transmission in which an automatic transmission automatically controls a stepless speed ratio.
The automatic transmission control apparatus is the transmission, continuously variable
Detection and engine braking force control actuator a, and the engine brake demand driving condition detecting means b for detecting whether the engine brake demand operating conditions, the locking tendency of the driven wheels for variably controlling the engine braking force by changing the width of the floor gear ratio And a control for weakening the engine braking force when the driving wheel is detected to be in the locked state and the driving wheel is in the locked state, as compared with the case where the driving wheel is in the non-locked state. a command and a engine braking force control means d to be outputted to the engine braking force control actuator a, the engine
The braking force control means determines that the drive wheels are
The target gear ratio is corrected to a smaller value when
The target gear ratio is set to decrease as the tendency to
Characterized in that it is.

[0011]

[0012]

When the driver performs a select operation to the engine brake range or the like in accordance with the engine brake request, the engine brake request operation state detection means detects the engine brake request operation state by the engine brake request operation state detection means. and, when the drive wheel is detected to be locking tendency by the driving wheel locking tendency detecting means c for detecting the locking tendency of the drive wheel, the drive wheel
Is closer to the locking tendency, the control command to decrease the target gear ratio and reduce the engine braking force by correction is output to the engine braking force control actuator a.

As described above, by controlling the engine braking force based on the prediction of whether or not the drive wheels have a tendency to lock,
The engine braking force is weakened as the driving wheels are more likely to lock, and reliably prevents driving wheel locks that impair drivability, especially on roads where the driving wheels are easily locked, such as on low μ roads. be able to.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, the configuration will be described.

FIG. 2 is a shift control system diagram of the shift control device of the continuously variable transmission (corresponding to the shift control device of the automatic transmission) according to the first embodiment of the present invention.

In FIG. 2, 1 is an engine, 2 is a continuously variable transmission, 3 is a stepping motor (corresponding to an engine braking force control actuator a), 4 is a CVT control unit, 5 is a select position switch, and 6 is a throttle opening. Reference numeral 7 denotes an output shaft speed sensor, 8 denotes an engine speed sensor, and 9 denotes other sensors and switches.

The continuously variable transmission 2 is, for example, a V-belt type continuously variable transmission (see Japanese Patent Application Laid-Open No. 62-122834) or a toroidal type continuously variable transmission (see Japanese Patent Application Laid-Open No. 2-292562).
The speed ratio is controlled by the rotation amount of the stepping motor 3 operated by a control command from the CVT control unit 4.

The select position switch 5 outputs a switch signal in accordance with an N range, a D range, a Ds range (emblem range), a P range, and an R range.

The throttle opening sensor 6 detects a throttle opening TVO.

The output shaft speed sensor 7 detects the output shaft speed Np (= vehicle speed VSP) which is the speed of the continuously variable transmission output shaft 2a connected to a propeller shaft (not shown).

The engine speed sensor 8 detects the engine speed Ne, which is the crankshaft speed of the engine 1.
Is detected.

Next, the operation will be described.

[Shift Control Operation] FIG. 3 is a flowchart showing the flow of the shift control operation performed by the CVT control unit 4. Each step will be described below.

In step 11, a select position switch signal (selector SW), a throttle opening TVO, an output shaft speed Np (vehicle speed VSP), and an engine speed Ne are input.

In step 12, the target input rotation Nt according to the vehicle speed VSP and the throttle opening TVO is retrieved from the D range map shown by the solid line in FIG.

In step 13, it is determined whether or not the select position switch signal is in the range for the emblem, that is, in the Ds range (corresponding to the engine brake required driving condition detecting means b). If it is not in the Ds range, the normal shift control in step 20 is performed.

In step 14, the target input rotation speed NTb for emblem according to the vehicle speed VSP and the throttle opening TVO is calculated as shown in FIG.
Is searched from the Ds range map indicated by the hatching.

In step 15, it is determined whether or not the target input rotation Nt is less than the emblem target input rotation Nteb. If Nt.gtoreq.Nteb, the normal speed change control of step 20 is performed.

In step 16, a target gear ratio it is calculated from the target input rotation for emblem NTeb and the vehicle speed VSP. The calculation of the target speed ratio it is performed by a calculation routine shown in FIG. That is, in step 16a,
It is calculated using the following equation: it = Nteb / VSP * K1 (K1; positive constant).

In step 17, the output shaft rotation change rate dN
p is calculated (corresponding to the drive wheel lock tendency detecting means c). The calculation of the output shaft rotation change rate dNp is performed by a calculation routine shown in FIG. That is, step 17a
Is calculated using the equation dNp = Np-Npold, and in step 17b, the current output shaft speed Np
Is set as the previous output shaft speed Npold.

In step 18, the output shaft rotation change rate dN
The gear ratio correction amount Δi is set by p. The gear ratio correction amount Δi is set by a gear shift correction amount setting routine shown in FIG. That is, in step 18a, dN
It is determined whether or not p <K2, and in step 18b, when dNp <K2, Δi = K4. In step 18c, it is determined whether dNp <K3,
In step 18d, when dNp <K3, Δi =
K5. If dNp ≧ K3, Δi = 0 in step 18e. However, K2, K3
Is a negative constant and K2 <K3, and K4 and K5 are gear ratio correction amounts and K4> K5.

In step 19, the stepping motor 3 as an actuator is operated so that the speed ratio = it-Δi.
Is output to the control command.

Steps 18 and 19 correspond to the engine braking force control means d.

[When selecting from D range to Ds range] The driver responds to the engine brake request by
When the range is selected from the range Ds, in the flowchart of FIG.
The flow proceeds from step 15 → step 16 → step 17 → step 18 → step 19.

Therefore, in the Ds range, control is performed to obtain a target speed ratio it according to the target input rotation for engine rev Nteb. In step 17, an output shaft rotation change rate dNp is calculated. 18
, The output shaft rotation change rate dNp (driving wheel deceleration)
The gear ratio correction amount Δi is set according to the magnitude of the gear ratio, that is, the degree of lock tendency of the drive wheels.
9, the target gear ratio is reduced (it−Δi) as the drive wheels are more likely to lock, and the D range gear ratio and D
s Shift control is performed to reduce the range of change in the range gear ratio.

According to the engine brake control based on the prediction of whether or not the drive wheels tend to lock, the engine braking force determined by the change range of the D range gear ratio and the Ds range gear ratio is such that the drive wheels have a lock tendency. As a result, the driving wheel lock which impairs the driving performance is surely prevented.

FIG. 8 shows D when the driving wheels tend to lock.
This is a time chart at the time of selection from the range to the Ds range. In the conventional shift control, control is performed to obtain a target speed ratio it corresponding to the target input rotation for rotation Nteb during the Ds range. As shown in the figure, when the engine braking force is excessive, for example,
On a low friction coefficient road or the like, the output shaft rotation rapidly drops to zero and the driving wheel is locked, whereas in the case of the present invention, the gear ratio correction amount Δi
, The range of change between the D range gear ratio and the Ds range gear ratio can be kept small, and the engine braking force weakens,
As indicated by the output shaft rotation characteristic indicated by the dotted line, the output shaft rotation gradually decreases to maintain the predetermined rotation speed, that is, the drive wheel lock is prevented.

If it is determined that the driving wheels do not tend to lock, then Δi = 0 in step 18e of the flow of FIG.
And the necessary engine braking force is secured.

Next, the effects will be described.

In the transmission control device for a continuously variable transmission that controls the engine braking force based on the change width of the transmission ratio, the transmission is controlled when the D range is selected from the D range and the output shaft rotation change rate dNp is large. When the wheels are detected to be locked, the control to weaken the engine braking force by correcting the change in the gear ratio to be smaller than when the drive wheels are not locked. It is possible to reliably prevent drive wheel lock that sometimes impairs drivability.

Reference Example First, the configuration will be described.

FIG. 9 shows a case where the technical idea of the present invention is applied to a shift control device of a multi-stage transmission for automatically controlling a multi-stage gear position .
If a shift control system diagram of.

In FIG. 9, reference numeral 21 denotes an overrun clutch solenoid (corresponding to an engine braking force control actuator a); 22, a shuttle shift valve; 23, an overrun clutch control valve; 24, an overrun clutch reducing valve; Overrun clutch (equivalent to engine brake clutch), 2
6 is an A / T control unit, 27 is a select position switch, 28 is a throttle opening sensor, 29 is an output shaft speed sensor, 30 is an engine speed sensor, and 31 is other sensors and switches.

The multi-stage transmission (not shown) is, for example, “RE4R
As in the case of the "01A type automatic transmission", the shift control is performed according to the throttle opening and the vehicle speed by electronic control. This power train employs a forward one-way clutch to improve the shift shock during downshifting Have been. This forward one-way clutch transmits the driving force from the engine to the driving wheels, but does not transmit the reverse driving force from the driving wheels due to idling. Therefore, for example, when selecting from the D range requiring the engine brake to the engine brake range, the engine brake is not effective. Therefore, the overrun clutch 25 is provided in parallel with the forward one-way clutch. 25 is secured to ensure the effectiveness of the engine brake when the engine brake is required.

The overrun clutch solenoid 21
Is controlled according to a duty control command from the A / T control unit 26, as shown in FIG.
An actuator that produces L. When the command to the overrun clutch solenoid 21 is OFF, the solenoid pressure PSOL becomes zero, and by setting the spool of the overrun clutch control valve 23 to the right position in the drawing, the line pressure is reduced via the overrun clutch reducing valve 24. The overrun clutch 25 is supplied to the overrun clutch 25 and is engaged. When the command to the overrun clutch solenoid 21 is ON, the solenoid pressure PSOL becomes the maximum pilot pressure, and by setting the spool of the overrun clutch control valve 23 to the left position in the drawing, there is no supply of line pressure and the overrun clutch Release 25. Therefore, by changing the duty ratio, which is the ON ratio, the solenoid pressure PSOL is controlled from zero pressure to the pilot pressure, whereby the engagement capacity of the overrun clutch 25 can be variably controlled.

The select position switch 27 is set to N range, P range, D range, engine brake range (1
A switch signal is output according to the fixed speed range or the fixed second speed range, and the R range.

The throttle opening sensor 28 detects the throttle opening TVO.

The output shaft speed sensor 29 detects the output shaft speed Np (= vehicle speed VSP), which is the speed of the multi-stage transmission output shaft connected to the propeller shaft.

The engine speed sensor 30 detects the engine speed Ne, which is the engine crankshaft speed.
Is detected.

Next, the operation will be described.

[Shift Control Operation] FIG. 10 is a flowchart showing the flow of the shift control operation performed by the CVT control unit 26. Each step will be described below.

In step 41, a select position switch signal (selector SW), a throttle opening TVO, an output shaft speed Np (vehicle speed VSP), and an engine speed Ne are input.

In step 42, a target gear position corresponding to the vehicle speed VSP and the throttle opening TVO is retrieved from the D range map. Here, the D range downshift line is shown by the solid line in FIG.

In step 43, it is determined whether or not the select position switch signal is within the engine brake range (corresponding to the engine brake required operating condition detecting means b).
If it is not the engine brake range, the normal shift control in step 49 is performed.

In step 44, the overrun clutch capacity C is determined according to the vehicle speed VSP and the throttle opening TVO. Here, the overrun clutch capacity C is shown in FIG.
The vehicle speed VSP and throttle opening T
If there is an operating point due to VO, it is determined to be 100%, otherwise it is determined to be 0%.

In step 45, the output shaft rotation change rate dN
p is calculated (corresponding to the drive wheel lock tendency detecting means c). The calculation of the output shaft rotation change rate dNp is performed by a calculation routine shown in FIG. That is, step 45
In step a, the output shaft speed Np is calculated using the formula dNp = Np-Npold.
Is set as the previous output shaft speed Npold.

In step 46, the output shaft rotation change rate dN
The overrun clutch capacity correction amount ΔC is set by p. This correction amount ΔC is set by an overrun clutch capacity correction amount setting routine shown in FIG. That is, it is determined in step 46a whether dNp <K2, and in step 46b, if dNp <K2, .DELTA.C = K4. In step 46c, d
It is determined whether or not Np <K3. At step 46d, if dNp <K3, .DELTA.C = K5. Also,
If dNp ≧ K3, in step 46e, ΔC
= 0. However, K2 and K3 are negative constants and K2 <K
3, K4 and K5 are the overrun clutch capacity correction amounts and K4
> K5.

In step 47, a duty control command is output to the overrun clutch solenoid 21 which is an actuator so that the overrun clutch capacity C = C−ΔC. Here, the duty ratio, which is the actuator operation amount, is calculated based on, for example, a relationship characteristic between the displacement and the actuator operation amount, as shown in FIG.

Steps 46 and 47 correspond to the engine braking force control means d.

In step 49, a target gear position corresponding to the vehicle speed VSP and the throttle opening TVO is retrieved from the engine brake range map, and a shift control for obtaining the target gear position is performed. The dotted line in FIG. 11 shows the engine brake range downshift line.

[At the time of selecting from the D range to the engine brake range] When the driver selects from the D range to the engine brake range in accordance with the engine brake request, in the flowchart of FIG. 46
The flow proceeds from step 47 to step 48.

Therefore, in the engine brake range, the engine brake control for engaging the overrun clutch 25 at 100% capacity is basically performed in the region where the throttle opening TVO is in the low opening range. The shaft rotation change rate dNp is calculated, and in step 46, the overrun clutch capacity correction amount ΔC is determined based on the magnitude of the output shaft rotation change rate dNp (driving wheel deceleration), that is, whether or not the drive wheel has a tendency to lock. Is set, and in step 47, the clutch capacity is made smaller as the driving wheels are more likely to lock (C-Δ
C) Control is performed to regulate the transmission of the reverse torque from the drive wheels by the clutch capacity.

By the engine brake control based on the prediction of whether or not the drive wheels tend to lock, the engine braking force determined by the engagement capacity of the overrun clutch 25 is reduced as the drive wheels tend to lock. Therefore, the drive wheel lock that impairs drivability is reliably prevented.

If it is determined that the drive wheels do not have a tendency to lock, then at step 46e in the flow of FIG.
It is set to 0, and the required engine braking force is ensured by the overrun clutch 25 being engaged with 100% engagement capacity.

Next, the effects will be described.

In a shift control device for a multi-stage transmission in which the engine braking force is controlled by the engagement capacity of the overrun clutch 25, when the shift from the D range to the engine brake range is selected and the output shaft rotation change rate dNp is large. When the drive wheels are detected as having a tendency to lock, a device that performs control to weaken the engine braking force by correcting the engagement capacity of the overrun clutch 25 to be smaller than when the drive wheels are likely to be unlocked,
It is possible to reliably prevent drive wheel lock that impairs drivability when selecting the engine brake range.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to the embodiment, and even if there are changes and additions without departing from the gist of the invention, the invention is included in the invention. It is.

For example, in the embodiment, the example in which the drive wheel lock tendency is detected by the output shaft rotation change rate has been described. However, the drive wheel lock tendency is detected by comparing the vehicle deceleration with the drive wheel deceleration. It may be detected by a ratio.

The means for detecting the required operating condition of the engine brake includes not only the detection of the select position but also the detection of the time of coasting with the accelerator pedal released from the vehicle.

In the embodiment, the example in which the correction amount is set stepwise has been described. However, the correction amount may be set by a continuous stepless correction amount map or a correction operation formula according to the drive wheel locking tendency. good.

[0072]

In the present invention, as has been described above, according to the present invention is variable continuously variable automatic transmission automatically controls the transmission ratio of the stepless
In a shift control device for an automatic transmission that is a high-speed gear, when it is detected that an engine brake is required and the drive wheel is locked, the drive wheel is locked.
The target gear ratio is made smaller so that the engine brake force is reduced by correcting the engine speed. Therefore, it is possible to surely prevent the driving wheel lock which impairs the driving performance when the engine brake control is performed. Can be

Further, since the driving wheel lock due to the engine brake can be prevented, the operating range in which the engine brake is effective can be expanded, and the load on the brake can be reduced. Further, since the energy consumed by the brake can be reduced, an effect of reducing fuel consumption can be expected in synergy with control such as engine fail cut.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims showing a shift control device for an automatic transmission according to the present invention.

FIG. 2 is a shift control system diagram of a shift control device of the continuously variable transmission according to the first embodiment.

FIG. 3 is a flowchart illustrating a flow of a shift control operation performed by the CVT control unit according to the first embodiment.

FIG. 4 is a shift map of the first embodiment.

FIG. 5 is a flowchart showing a target gear ratio calculation routine in the first embodiment.

FIG. 6 is a flowchart showing an output shaft rotation change rate calculation routine in the first embodiment apparatus.

FIG. 7 is a flowchart showing a gear ratio correction amount setting routine in the first embodiment.

FIG. 8 is a comparison characteristic diagram comparing a transmission ratio characteristic and an output shaft rotation characteristic of the present invention with a conventional example at the time of selection from the D range to the Ds range.

FIG. 9 is a shift control system diagram of a shift control device for a multi-stage transmission according to a reference example .

FIG. 10 is a flowchart illustrating a flow of a shift control operation performed by an A / T control unit according to a reference example .

FIG. 11 is a shift map diagram of the reference example device.

FIG. 12 is a flowchart illustrating an output shaft rotation change rate calculation routine in the reference example apparatus.

FIG. 13 is a flowchart illustrating an overrun clutch capacity correction amount setting routine in the reference example apparatus.

FIG. 14 is a characteristic diagram showing a relationship between a displacement and an actuator operation amount in the reference example device.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-106715 (JP, A) JP-A-4-54371 (JP, A) JP-A-2-80858 (JP, A) JP-A-1- 262230 (JP, A) JP-A-6-42623 (JP, A) JP-A-61-70254 (JP, A) JP-A-60-215434 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48 F16H 9/00

Claims (2)

(57) [Claims] An automatic transmission automatically controls a stepless speed ratio.
Transmission control device for automatic transmissions
An engine brake force control actuator that variably controls the engine brake force according to the step width of the stepless speed change ratio, an engine brake request operation state detection unit that detects whether the engine brake request operation state is established, and a driving wheel lock tendency. Drive wheel lock tendency detecting means for detecting, and control for weakening the engine braking force when the drive wheel is in a lock tendency and the driving wheel is in a lock tendency state when the driving condition is the engine brake required driving condition. comprising an engine braking force control means for outputting a command to the engine braking force control actuator, wherein the engine braking force control means, the drive wheel is locked tilt
Direction, the target gear ratio is corrected to be small, and the correction is
The higher the tendency to lock the drive wheels, the smaller the target gear ratio
A shift control device for an automatic transmission, wherein the shift control is performed as follows. 2. A shift control device for an automatic transmission according to claim 1, wherein said engine braking force control means includes a drive range.
When selecting to the range for emblem and drive
Drive wheel locks when wheel is detected to be prone to locking
The more the tendency, the more the drive range gear ratio and emblem
Control that keeps the change range of the range gear ratio small
A shift control device for an automatic transmission, characterized by weakening engine braking force .