JPH0221066A - Automatic engine brake controller for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent a car speed from being increased suddenly as an up shift speed change is conducted during an automatic engine brake, by prohibiting other speed changes except for the time of foot brake operation, during a down shift speed change for engine brake. CONSTITUTION:When there occurs the state of operation in which an engine brake is necessary, an automatic engine brake means, in accordance with the signal of an engine brake necessary condition discriminating means inspecting this, exerts an engine brake by conducting a down shift speed change putting an automatic transmission to a low speed step. During this down shift speed change, a speed change prohibiting means, in response to a brake inspecting means inspecting the operation of foot brake and an automatic engine brake inspecting means inspecting the down shift speed change, fixes a signal from the engine brake necessary condition discriminating means except for the time of foot brake operation, and prohibits other speed changes. Thus, an engine brake necessary condition discrimination is conducted only at the time of foot brake operation, and there is no feeling of discordance due to the sudden increase of a car speed during an automatic engine brake.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device that downshifts an automatic transmission in a driving state that requires engine braking, thereby automatically providing engine braking. It is something.

(Prior Art) This type of automatic engine brake control device is designed to apply the engine brake during braking, for example, as described in Nissan Motor Corporation mrL4N71B type, E4N71B type automatic transmission maintenance manual, (8261CO4). It is known that when the conditions are met, the automatic transmission is downshifted to a low gear and the vehicle continues to travel in this low gear. This automatic engine brake control device continuously determines how much engine braking is required even during a downshift for engine braking, and shifts to a gear position according to the request.

(Problem to be Solved by the Invention) However, in such a conventional configuration, there is a possibility that an upshift or an excessive downshift may be performed even during automatic engine braking, and a sudden increase or decrease in vehicle speed may cause the driver to There was a fear that it might give off a sense of discomfort.

(Means for Solving the Problem) The present invention attempts to solve the above-mentioned problem by prohibiting other gear changes except when the foot brake is activated during downshift gear change for engine braking. As shown in the concept, when an operating state that requires engine braking is reached, automatic engine braking means responds to a signal from an engine braking requirement determination means that detects this, and the engine is downshifted to a low gear and automatically applies engine braking. In the automatic transmission according to the present invention, there is provided a brake detection means for detecting operation of a footbrake, an automatic engine brake detection means for detecting a downshift by the automatic engine brake, and an operation of the footbrake during the downshift. The present invention is characterized by further comprising a gear change prohibiting means for fixing the signal from the engine brake necessary condition determining means so as to prohibit other gear changes except when the vehicle is in use.

(Function) When an operating state that requires engine braking is reached, the automatic engine braking means downshifts the automatic transmission to a low gear in response to a signal from the engine braking requirement determination means that detects this state. This allows engine braking to be applied.

By the way, during a downshift by the automatic engine brake means, the shift prohibiting means responds to the brake detection means for detecting the operation of the foot brake and the automatic engine brake detection means for detecting the downshift. The signal from the engine brake requirement determining means is fixed except when the brake is applied, and other gear changes are prohibited. Therefore, engine braking requirements are determined only when the foot brake is activated, and it is possible to prevent the driver from feeling uncomfortable due to a sudden increase in vehicle speed caused by upshifting during automatic engine braking.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

Figure 2 shows functional blocks of an embodiment of the present invention device configured to be useful for a 4-speed automatic transmission with OD (overdrive) described in Nissan Motor Co., Ltd. rRE4ROIA Type Automatic Toss Transmission Maintenance Manual J (A261CO7). In the diagram, l is an automatic transmission, 2 is a shift control means thereof, 3 is a gear position W determining means based on a shift pattern, and 4 is a manual engine brake selection means. The vehicle speed detection means 5 and the deceleration detection means 6 include a vehicle speed sensor (not shown) that picks up the teeth of a pulse gear that rotates together with the output shaft of the automatic transmission 1 and generates a pulse signal. Then, every time a pulse signal is generated, the program shown in FIG. 3(a) is executed to increment the counter C, and
The program shown in FIG. 3(b) is executed by a regular interrupt every 5 ec or 354 m5 ec to determine the vehicle speed νSP and the vehicle deceleration α. In FIG. 3 0)), the counter C is cleared in step 24, so the count value of the counter C at the time of the interrupt corresponds to the vehicle speed vSP, and the difference between this count value C and the previous value C' is It corresponds to the acceleration/deceleration α of the vehicle. Therefore, first step 2
0, the vehicle speed vSP is determined as a function f (C) of the count value C, and in step 21, the previous value C' and current value C of the counter are calculated.
Step 2
2, the vehicle deceleration α is expressed as a function g(ΔC) of this difference ΔC.
is determined, and in step 23, the current count value C is set as C' and stored in memory for the next time. Note that in order to obtain the deceleration α, the longitudinal G of the vehicle may be used instead of the vehicle speed vsp.

The manual engine brake selection means 4 is operated by the driver when the driver desires engine braking (overdrive prohibition switch, manual pulp ■ range or ■ range position), and the gear position determining means 3 receives the manual engine brake signal from the means 4. If the manual engine brake signal is input, the vehicle speed vsp and other gear shift control information 1 are determined based on the corresponding gear shift pattern, or based on the normal gear shift pattern if the manual engine brake signal is not input.
3 (throttle opening TH, hydraulic oil temperature, etc.). The shift control means 2 controls the automatic transmission 1 to shift to the required gear position.

The downshift gear determining means 7 for automatic engine braking downshifts the automatic transmission 1 to a gear position lower than the gear position selected by the shift control means 2 under driving conditions that require engine braking, and also downshifts the automatic transmission 1 to a gear position lower than the gear position selected by the shift control means 2. means 3 to determine whether engine braking is necessary.
In addition to manually inputting the requested gear position from the vehicle, vehicle speed vsp from the means 5, deceleration (α) information from the means 6, and manual engine brake signal from the means 4, the brake detection means 9 detects depression of the brake pedal 8. The setting delay time of the off-delay setting means 12 in response to the signal from the idle state detection means 11 which detects the release of the accelerator pedal 10 is manually set. It is assumed that the means 12 sets a time for delaying the depression signal when the accelerator pedal 10 is depressed again from the released state.

4 and 5 show control programs for the automatic engine braking downshift speed determining means 7. FIG.

In FIG. 4, in step 30, it is checked whether the manual valve is in the forward automatic shift range (CD). Since the automatic engine brake according to the present invention is not required in ranges other than the D range, that is, in the 2nd speed engine brake (II) range and the 1st speed engine brake (1) range,
Flag FDS indicating a downshift speed change command for automatic engine braking in step 31 2. Reset each FDS 3. When FDS2 is set to 1, the second
(to issue a downshift command for automatic engine braking to 3rd gear and prohibit upshifting to 3rd gear or higher), FD
S3, when set to 1, issues a downshift command for automatic engine braking to 3rd gear (prohibits upshifting to 4th gear).

If step 30.32 determines that the vehicle is in D range and the accelerator is released, step 33 checks to see if the idle flag FID is already set to 1, and if it is not, step 34.35 indicates that the accelerator is released. P
Set IDL = 1, and further set FDS2゜FDS3 to 0.
Reset to . If it is determined in step 33 that FIDL has already been set to 1, in step 36 the driver
A check is made as to whether or not prohibition of D is desired, and if so, step 35 is executed to prohibit downshifting for automatic engine braking to third gear.

In the next step 41, FDS2=1 or FDS3 is already
Checks whether the automatic engine brake is activated or not depending on whether = 1 or not. When the automatic engine brake is not activated with FDS2=O and FDS3=0, it is checked in step 42 whether or not the foot brake is being applied during braking, and during braking that requires automatic engine braking, the following request is made. It determines the engine braking force and issues a corresponding downshift command for automatic engine braking.

That is, in steps 44 and 45, it is checked whether the currently used gear position is 4th speed or 3rd speed. If it is the fourth speed, in step 46 the vehicle deceleration ΔC (see Figure 3) is set to the set value ΔC1l.
Check whether it is lt4 or higher, and if it is lower than that, keep the automatic engine brake (FDS2, FDS3) as it is, and if it is higher than that, go to step 47 to determine whether the vehicle speed range is VL42<VSP<ν)142 where 4→2 downshift should be performed. , Vehicle speed range in which 4→3 downshift should be performed in step 48 VL
41<VSP<VH43. Then, the FDS responds to the request in steps 49 and 50 for each vehicle speed range.
2=1 or FDS3=1 shift command,
FDS 2. Keep FDS 3 as it is. Note that if it is determined in step 42 that the foot brake is not activated, that is, if the automatic engine brake has never been set, this automatic engine brake non-activation state is continued.

If it is determined in step 45 that the 3rd gear is being selected, in step 51 it is determined whether the vehicle deceleration ΔC is greater than or equal to the set value ΔC5et3, and in step 52 it is determined whether the vehicle speed range in which the 3→2 downshift is to be performed is VL: +z<VSP< Checks whether it is VH3z or not, and when both conditions are satisfied, FDS 2-
1 sets the 3→2 downshift speed change command.

If it is determined in step 41 that a downshift for automatic engine braking has already been performed, step 43
Check whether the downshift timer TDS is 0 or not. This timer TDS is set at step 49°50 or 53
When issuing a downshift gear change command for automatic engine braking,
In step 54, the set time TDS set is set, and the program shown in FIG.
Therefore, in step 43, it is checked whether a set time TDS set has elapsed since the downshift for automatic engine braking. Until the time elapses, end the control as is and press F.
DS2. The FDS 3 is kept as it is, and as a result, other shifts are prohibited by maintaining the downshift gear for automatic engine braking set in steps 44-53. As a result, even during automatic engine braking, an upshift is performed and the vehicle speed suddenly increases, which can relieve the driver's discomfort.

When the set time TDS set has elapsed, the control is advanced from step 43 to step 42 to cancel the above-mentioned shift prohibition, and if braking is in progress with the foot brake activated, the requested engine brake is applied in steps 44 to 53. The requested engine braking is obtained by allowing a shift to the corresponding gear position. Therefore,
During automatic engine braking, a new gear shift determination is not made unless the foot brake is activated, which eliminates the driver's discomfort caused by upshifts being made and the vehicle speed suddenly increasing even during automatic engine braking. . Further, by providing the timer TDS, it is possible to avoid the disadvantage that the above-mentioned shift prohibition continues indefinitely and a gear position that does not match the requested engine brake is held for an undesirably long time.

If it is determined in step 32 that the accelerator pedal is being depressed, then in step 55 it is checked whether the idle flag FIDL is 1 or not to see if the accelerator has been released so far, that is, whether or not the accelerator pedal is being depressed again. In the case of re-depression, a delay time DLY is set in the timer T in step 56, and the idle flag FIDL is reset to 0 to indicate the accelerator pedal depression state. If it is determined in step 55 that the pedal is not depressed again, these processes are skipped and the control proceeds to step 62. The above delay time DLY is when the accelerator pedal is depressed again, and the downshift gear shift for automatic engine braking (FDS2=1.FDS
3=1) immediately ends (FDS2=O, FDS 3=
O) This is to allow the process to be completed later without being executed.

In step 62, when the timer T, which is decremented by the regular interrupt of the program shown in FIG. , flag FDS2=O, FDS3-0 to terminate automatic engine braking.

6 and 7 show control programs by the speed change control means 2 and gear position determining means 3 in FIG. 2.

In FIG. 6, first, in step 80, vehicle speed vsp, throttle opening Tl+, etc. indicating the driving state are read, and
In step 81, the target gear position G corresponding to the vehicle speed vSP and throttle opening T)1 etc. is determined based on the manual valve selection range and the shift pattern depending on whether OD is prohibited.
Determine P. In the next step 83.84, automatic engine brake is not activated (FDS3=O.

FDS2=O) or during 3rd gear engine braking (FDS
3=1) or during 2nd gear engine braking (FDS 2=
1) Check. While the automatic engine brake is not operating, step 85 is directly executed to perform normal speed change control so that the gear position becomes the target gear position GP determined in step 81.

During 3rd gear engine braking, it is checked in step 86 whether the target gear position GP is higher than 3rd gear. If it is, then in step 87 GP is set to 3, and then step 85 is executed to shift down to 3rd gear. Shift gears and apply automatic engine braking. If GP<3, there is no need to shift gears to 3rd gear for engine braking, so step 8.
After this shift command is canceled by FDS3=O in step 8, normal shift control is performed by executing step 85.

During 2nd gear engine braking, it is checked in step 89 whether the target gear position GP is higher than 2nd gear, and if it is, then in step 90 GP is set to 2, and then step 85 is executed to downshift to 2nd gear. If GP<2, there is no need to downshift for 2nd gear engine braking, so in step 91 FDS2=
After this shift command is canceled by O, normal shift control is performed by executing step 85.

Depending on the powertrain of the automatic transmission, 2nd gear,
When engine braking is required in third gear, an engine braking clutch must be activated, and in the automatic transmission described in the above document to which this example device is applied, an overrun clutch is used for this purpose. Equivalent to. This engine braking clutch enables engine braking in the second and third gears by controlling its operation according to the control program shown in FIG. That is, step 92
If it is determined in step 93 or 94 that the throttle opening TH is less than the minute setting value, and it is determined in step 93 or 94 that automatic engine braking is in progress with FDS 2 = 1 or FDS 3 = 1, the engine brake clutch is engaged in step 95. and enable engine braking as requested. However, in other cases, since engine braking is not necessary, the engine braking clutch is released in step 96.

(Effects of the Invention) As described above, the automatic engine brake control device of the present invention is configured to prohibit other gear changes except when the foot brake is activated during a downshift for engine braking, so that the engine brake is required only when the foot brake is activated. Since the condition is determined, it is possible to prevent the driver from feeling uncomfortable due to an upshift being performed during automatic engine braking and the vehicle speed suddenly increasing.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the automatic engine brake control device of the present invention, Fig. 2 is a functional block diagram showing one embodiment of the device of the present invention, and Figs. 3 to 7 show control programs on the same side, respectively. It is a flowchart. 1... Automatic transmission 2... Speed change control means 3.
...Gear position determining means 4...Manual engine brake selection means 5...
Vehicle speed detection means 6...Deceleration detection means 7...Downshift determination means for automatic engine braking 9...Braking operation detection means 11...Idle state detection means 12...Off-delay setting means Patent applicant Nissan Jidosha Co., Ltd.

Claims (1)

[Claims] 1. Automatic engine braking means responds to a signal from an engine braking requirement determining means that detects when an operating state requiring engine braking is reached, and downshifts to a low gear to automatically provide engine braking. In the automatic transmission, the brake detection means detects the operation of the foot brake; the automatic engine brake detection means detects when the automatic engine brake means is in the process of downshifting; An automatic engine brake control device for an automatic transmission, comprising: a shift prohibiting means for fixing a signal from the engine brake necessary condition determining means so as to inhibit shifting.