JP3770056B2 - Shift shock reduction device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention has a shift pattern different from the normal shift pattern, and these shift patterns are automatically switched and selected according to the driving conditions, and the shift is performed by switching the friction elements based on the selected shift pattern. The present invention relates to a shift shock reducing device for an automatic transmission.
[0002]
[Prior art]
An automatic transmission usually has a plurality of planetary gear sets as described in, for example, “RE4RO1A Automatic Transmission Maintenance Manual” (A261CO7) issued by Nissan Motor Co., Ltd. Usually, the transmission path (shift stage) is determined by selective engagement of various friction elements such as a hydraulic clutch and a hydraulic brake, and a shift to another shift stage is performed by switching engagement / release of the friction element. .
[0003]
Here, as described in the above-mentioned document, when the above-mentioned gear shift is performed, a gear speed suitable for the current driving state is obtained based on a predetermined gear shift pattern, and the friction element is engaged so that the gear shift to this is performed. It is normal to perform a switch.
By the way, the planned shift pattern is naturally determined in advance for traveling on a flat road, which is the most general traveling road surface. Therefore, in the shift control based only on the regular shift pattern, during traveling on an uphill road, There is a problem in that it is impossible to drive crisply due to insufficient torque, or to frequently depress the brake pedal due to insufficient engine brake when braking the vehicle.
[0004]
Therefore, conventionally, as described in, for example, Japanese Patent No. 2585273, in addition to the commonly used first shift pattern, a second shift pattern set to a lower gear selection tendency is added, and the vehicle is traveling on an uphill road. An automatic transmission has been proposed in which a shift pattern is automatically selected and switched from a first shift pattern to a second shift pattern, and shift control is performed based on the second shift pattern.
[0005]
[Problems to be solved by the invention]
Thus, in an automatic transmission that switches between the normal shift pattern and the second shift pattern, the operating conditions such as the accelerator pedal depression amount and the vehicle speed that are different from the normal ones are changed while being switched to the second shift pattern. And the fact that the above-mentioned switching from the normal shift pattern to the second shift pattern is automatically performed and the driver cannot detect this, so it is not expected for the driver. This is an unexpected shift that occurs when it is not available, and even during the same shift, the shock during the shift based on the second shift pattern tends to feel greater than the shock during the shift based on the regular shift pattern.
[0006]
Conventionally, however, the shift shock mitigation operation is usually executed in the same way even when the shift pattern is switched, and the operation amount for the shift shock countermeasure is also based on the second shift pattern even during the shift based on the normal shift pattern. The same is true for shifting.
For this reason, it has been confirmed that the shift shock felt by the driver at the time of shifting based on the latter second shift pattern cannot be sufficiently reduced, and is insufficient as a countermeasure for shifting shock.
[0007]
According to a first aspect of the present invention, there is proposed a shift shock reduction device for an automatic transmission that realizes the solution of the above problem by increasing an operation amount for shifting shock reduction during a shift based on a second shift pattern. For the purpose.
[0008]
According to a second aspect of the present invention, there is proposed a shift shock reducing device for an automatic transmission that can achieve the same effect as that of the first aspect of the invention when the shift shock is reduced by reducing the torque of the power source. For the purpose.
[0009]
According to a third aspect of the present invention, in the case where the shift shock is reduced by reducing the fastening pressure of the friction element, the same effect as the first aspect of the invention can be achieved. The object is to propose a device.
[0010]
According to a fourth aspect of the present invention, the shift shock is reduced by transiently controlling the engagement pressure of the friction element so that the input / output rotation speed ratio or the input rotation speed of the automatic transmission changes at a predetermined change rate. An object of the present invention is to propose a shift shock reducing device for an automatic transmission that can achieve the same effects as those of the first invention.
[0011]
According to a fifth aspect of the present invention, the shift pattern can be switched so that a required driving torque can be output when the road surface gradient is switched to an uphill gradient. It is an object of the present invention to propose a shift shock reducing device for an automatic transmission that can achieve the same effect as the above.
[0012]
According to a sixth aspect of the present invention, it is possible to switch the shift pattern so that a predetermined engine brake can be obtained during braking of the vehicle, and at the same time, the same effect as that of the first aspect of the invention can be obtained when the shift pattern is switched. An object of the present invention is to propose a shift shock reducing device for an automatic transmission that can be achieved.
[0013]
[Means for Solving the Problems]
For these purposes, first, the shift shock reducing device for an automatic transmission according to the first invention is:
A first shift pattern that is normally used and a second shift pattern in which a shift occurs under an operating condition different from the first shift pattern is automatically selected according to the operating condition, and the selected shift pattern In an automatic transmission that performs shifting by switching engagement of friction elements based on
An operation amount for reducing a shift shock that occurs during the shift is configured to be larger during a shift based on the second shift pattern than during a shift based on the first shift pattern. .
[0014]
A shift shock reducing device for an automatic transmission according to a second invention is the first invention,
The shift shock is reduced by reducing the torque of the power source in the preceding stage of the automatic transmission during the shift, and the decrease amount of the power source torque is less than that during the shift based on the first shift pattern. It is characterized in that it is configured to increase at the time of shifting based on this shifting pattern.
[0015]
A shift shock reducing device for an automatic transmission according to a third invention is the first invention or the second invention,
The shift shock is reduced by reducing the engagement pressure of the friction element during a shift, and the decrease amount of the engagement pressure is based on the second shift pattern rather than the shift based on the first shift pattern. It is characterized in that it is configured to increase at the time of shifting.
[0016]
A shift shock reducing device for an automatic transmission according to a fourth invention is the first invention or the second invention,
The shift shock is reduced by transiently controlling the engagement pressure of the friction element so that the input / output rotation speed ratio or the input rotation speed of the automatic transmission changes at a predetermined change rate during shifting. Is configured to be smaller at the time of shifting based on the second shift pattern than at the time of shifting based on the first shift pattern.
[0017]
A shift shock reducing device for an automatic transmission according to a fifth invention is any one of the first to fourth inventions,
When the road surface gradient is switched to an upward gradient greater than the set value, the selection is switched from the first shift pattern to the second shift pattern, and the second shift pattern is a shift pattern that tends to select a lower gear than the first shift pattern. It is characterized by this.
[0018]
A shift shock reducing device for an automatic transmission according to a sixth aspect of the invention is any one of the first to fourth aspects of the invention.
When the vehicle enters a braking state higher than the set value, the selection is switched from the first shift pattern to the second shift pattern, and the second shift pattern is a shift pattern that tends to select a lower gear than the first shift pattern. It is characterized by.
[0019]
【The invention's effect】
The first shift pattern and the second shift pattern that are normally used are automatically selected according to the driving conditions, and the automatic transmission performs a shift by switching the engagement of the friction element based on the selected shift pattern.
By the way, in the first aspect of the invention, the operation amount for reducing the shift shock generated at the time of the shift is made larger at the time of shifting based on the second shift pattern than at the time of shifting based on the first shift pattern.
[0020]
For this reason, while being switched to the second shift pattern, a shift shock occurs unexpectedly under different driving conditions from the shift based on the first shift pattern that is normally used. However, the shift shock can be surely reduced so as to eliminate this tendency, and the shock during the shift based on the second shift pattern can also be reduced in the same manner as during the shift based on the first shift pattern. it can.
[0021]
In the second aspect of the invention, the shift shock is reduced by the torque drop of the power source during the shift, and the torque drop amount of the power source is based on the second shift pattern rather than the shift based on the first shift pattern. To increase the speed during shifting,
In the case where the shift shock is reduced with high response due to a decrease in torque of the power source, the same effect as that of the first invention can be achieved.
[0022]
In the third aspect of the invention, the shift shock is reduced by reducing the fastening pressure of the friction element at the time of shifting, and the amount of decrease in the fastening pressure is set to be lower than that at the time of shifting based on the first shift pattern. To increase during shifting based on the shifting pattern,
In the case where the shift shock is reduced by reducing the fastening pressure of the friction element, the same effect as that of the first invention can be achieved.
[0023]
In the fourth aspect of the invention, the shift shock is reduced by transiently controlling the engagement pressure of the friction element so that the input / output rotation speed ratio or the input rotation speed of the automatic transmission changes at a predetermined change rate at the time of shifting. In order to make the predetermined change rate smaller at the time of shifting based on the second shift pattern than at the time of shifting based on the first shifting pattern,
The same effect as the first invention is achieved when the shift shock is reduced by transiently controlling the engagement pressure of the friction element so that the input / output rotation speed ratio or the input rotation speed of the automatic transmission changes at a predetermined change rate. can do.
[0024]
In a fifth aspect of the present invention, the shift pattern switching described above is a pattern switch that allows a selection to be switched from the first shift pattern to the second shift pattern when the road surface gradient is switched to an ascending slope that is greater than or equal to the preset value. Since the shift pattern is more likely to select a lower gear than the first shift pattern,
It is possible to output the driving torque required when the road surface gradient is switched to the upward gradient by switching the shift pattern, and to prevent the driver from feeling a significant shift shock even after the shift pattern is switched.
[0025]
In a sixth aspect of the invention, the pattern change is a pattern change that allows the selection to be switched from the first shift pattern to the second shift pattern when the vehicle is in a braking state that is greater than or equal to the set value. Because of the shifting pattern that tends to select a lower gear than the shifting pattern of
A predetermined engine brake required at the time of braking of the vehicle can be achieved by the above-described shift pattern switching, and the driver can be prevented from feeling a large shift shock even after the shift pattern switching.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a power train of a vehicle equipped with a shift shock reducing device for an automatic transmission according to an embodiment of the present invention and a control system thereof, and an engine 1 and an automatic shift using the power train as a power source. It is configured by tandem coupling with the machine 2.
[0027]
The engine 1 is controlled by the engine controller 3 so as to generate an output corresponding to the throttle opening determined in conjunction with the accelerator pedal.
The automatic transmission 2 has a line pressure solenoid 7 similarly inserted in the control valve 4 by a combination of ON and OFF of the shift solenoids 5 and 6 inserted in the control valve 4 when the driver selects the travel range. It is possible to selectively engage a friction element such as a hydraulic clutch or a hydraulic brake with a line pressure determined by the driving duty D to select a predetermined gear position and output the engine rotation at the gear speed.
[0028]
The ON / OFF of the shift solenoids 5 and 6 and the drive duty D of the line pressure solenoid 7 are determined by the controller 8, and for this reason, the controller 8
A signal from a throttle opening sensor 11 for detecting the throttle opening TVO of the engine 1;
A signal from the vehicle speed sensor 12 for detecting the vehicle speed VSP;
A signal from a transmission input rotation sensor 13 for detecting a transmission input rotation speed Ni;
Road surface gradient (θ) information from the in-vehicle navigation system 14;
A signal from the brake fluid pressure sensor 15 for detecting the brake fluid pressure P _B in the vehicle brake system is input.
[0029]
Based on the input information described above, the controller 8 first executes the control program of FIG. 2 to select the shift pattern of FIG. 3A or 3B, and then selects the automatic transmission based on the selected shift pattern. At the same time that the gear 2 is controlled to shift, the shift shock mitigating action shown in FIG.
[0030]
First, the shift pattern selection program of FIG. 2 will be described. In step 21, it is checked whether or not the road surface gradient θ is greater than or equal to a predetermined value, and in step 22 whether or not the brake fluid pressure P _B is greater than or equal to a predetermined pressure.
When it is determined in these steps that the road surface gradient θ is less than the predetermined gradient and the brake fluid pressure P _B is also less than the predetermined pressure, in step 23, the commonly used FIG. 1) is selected.
Therefore, when it is determined in step 21 that the road surface gradient θ is greater than or equal to the predetermined gradient, or in step 22 where it is determined that the brake fluid pressure P _B is greater than or equal to the predetermined pressure, step 24 is illustrated in FIG. The second shift pattern shown in FIG. 3B is selected, in which each shift line is located on the higher vehicle speed side than the first shift pattern and the low-speed stage selection tendency is selected.
[0031]
In each of the shift patterns shown in FIGS. 3 (a) and 3 (b), each shift line is displayed on the two-dimensional map of the vehicle speed VSP and the throttle opening TVO as usual, and the shift speeds (first speed to fourth speed) are displayed. ) It is assumed that each shift line has hysteresis between the upshift line and the downshift line to prevent hunting in the shift control.
However, in FIG. 3, the upshift line and the downshift line are shown as common shift lines for the sake of clarity of the drawing.
[0032]
The controller 8 performs the following shift control based on the shift pattern selected as described above.
That is, from the throttle opening TVO detected by the sensor 11 and the vehicle speed VSP detected by the sensor 12, the first regular shift pattern shown in FIG. 3A selected as described above or the second shift shown in FIG. Based on this shift pattern, a shift speed suitable for the current operating state is obtained, and when this preferable shift speed and the currently selected shift speed do not coincide with each other, a shift solenoid 5, 6 is switched on and off.
[0033]
By the way, when the road surface gradient θ is greater than or equal to a predetermined gradient or the brake fluid pressure P _B is greater than or equal to a predetermined pressure as the shift pattern used for the shift, the first commonly used shift shown in FIG. Since the second shift pattern shown in FIG. 3 (b), which has a lower gear selection tendency than the pattern, is selected,
A tendency to select a low speed on an uphill road can be achieved, and it is possible to achieve crisp traveling on an uphill road, and a low speed stage tends to be selected even during braking, and a predetermined engine brake required during braking can be achieved.
[0034]
Further, the controller 8 executes a shift shock countermeasure as shown in FIG. 4 during the shift described above.
That is, during the shift based on the normal first shift pattern, as shown in FIG. 4A, the common line pressure P _L used to fasten all the friction elements is determined based on the throttle opening TVO based on FIG. Therefore, the line pressure P _{L1 is changed} to the normal line speed P _L1 at the time of shifting, and the line pressure P _L is decreased by ΔP _L1 from the value at the time of non-shifting at the shift command instant t ₁ .
[0035]
At the same time the controller 8 sets the Do [Delta] T _d1 small as usual as the engine torque reduction amount [Delta] T _d to the shift start instant t _2, instructs the torque reduction amount [Delta] T _d to the engine controller 3, as shown in FIG.
The engine controller 3 reduces the engine output torque by the torque reduction amount ΔT _d = ΔT _d1 by an operation such as delaying the ignition timing of the engine 1.
[0036]
Due to the line pressure reduction control of the automatic transmission 2 at the time of the shift described above, the engagement capacity of the friction element that is engaged at the time of the shift is reduced, and the torque reduction control of the engine 1 at the time of the shift causes a shift shock. Rotational inertia is reduced, and the shift shock can be reduced by the transmission output torque waveform shown in FIG.
[0037]
Incidentally, during the shift based on the second shift pattern illustrated in FIG. 3 (b), first was determined according to the throttle opening TVO based on FIG. 5 (b) the line pressure P _L as shown in FIG. 4 (b) The shift line pressure P _{L 2} for the two shift patterns is used, and the line pressure P _L is reduced by ΔP _{L 2} from the value at the non-shift at the shift command instant t ₁ to reduce shift shock. Here, the shift line pressure P _{L 2} for the second shift pattern shown in FIG. 5 (b), conventional shown in FIG. (A) (first) lower than the transmission line pressure P _L1 for shift pattern The shift shock reduction line pressure drop amount ΔP _{L 2} (operation amount for shift shock reduction) when the second shift pattern is selected is used as the shift shock reduction line pressure drop amount when the normal (first) shift pattern is selected. It should be larger than ΔP _{L 1} (operation amount for reducing shift shock).
[0038]
Further, the controller 8 as in FIG. 4 (b), set a larger [Delta] T _d2 than normal [Delta] T _d1 mentioned above the shift start instant t ₂ as the engine torque reduction amount [Delta] T _d, in Figure 1 the torque reduction amount [Delta] T _d Command the engine controller 3 as shown.
The engine controller 3 reduces the engine output torque by the above-described torque down amount ΔT _d = ΔT _d2 by an operation such as delaying the ignition timing of the engine 1, and the speed change is also caused by the decrease of the rotational inertia that causes the shift shock. Shock can be reduced, and in combination with the above-described line pressure reduction control, the transmission shock can be reduced like the transmission output torque waveform shown in FIG.
[0039]
By the way, in the present embodiment, the operation amounts (line pressure decrease amount ΔP _{L 2} and torque down amount ΔT _d2 ) for reducing the shift shock during the shift based on the second shift pattern are used as the regular (first) shift. Since the operation amount (line pressure decrease amount ΔP _{L 1} and torque down amount ΔT _d1 ) for reducing the shift shock at the time of shifting based on the pattern is made larger,
While switching to the second shift pattern, even though the shift is unexpectedly generated under different driving conditions from the shift based on the first shift pattern that is normally used, the shift shock tends to be felt greatly, The shift shock can be surely reduced to eliminate this tendency, and the shock at the time of shifting based on the second shift pattern can also be reduced as in the case of the shifting based on the first shift pattern.
[0040]
In the above-described embodiment, when reducing the engagement shock by reducing the engagement capacity of the friction element, the line pressure P _L that is the engagement source pressure of the friction element is reduced and the engagement pressure of the friction element is operated during the shift. However, instead of this, as described in Japanese Patent Laid-Open No. 10-238620, transmission input / output between the transmission input rotational speed Ni and the transmission output rotational speed (which can be calculated from the vehicle speed VSP). The engagement pressure of the friction element is changed so that the rotation speed ratio changes at a predetermined change rate, or the transmission input rotation speed Ni changes at a predetermined change rate with the transmission output rotation speed during shifting being considered constant. Even when the shift shock is reduced by directly performing transient control (decreasing the engagement speed of the friction element), the countermeasure according to the present invention can be applied based on the same concept.
[0041]
In this case, as is apparent from the time change rate of the transmission input rotational speed Ni in FIGS. 4A and 4B, the predetermined change rate is set to be greater than when the normal (first) shift pattern is selected. Is reduced when the second shift pattern is selected, and when the second shift pattern is selected, the transmission input / output rotational speed ratio or the transmission input rotational speed Ni changes at the small change rate. Thus, the shift shock is reduced by directly transiently controlling the engagement pressure of the friction element (reducing the engagement speed of the friction element greatly).
[0042]
Also in the present embodiment, the operation amount (amount of decrease in the engagement speed of the friction element) for reducing the shift shock during the shift based on the second shift pattern is used as the shift during the shift based on the regular (first) shift pattern. Because it is larger than the operation amount for shock reduction,
While switching to the second shift pattern, even though the shift is unexpectedly generated under different driving conditions from the shift based on the first shift pattern that is normally used, the shift shock tends to be felt greatly, The shift shock can be surely reduced to eliminate this tendency, and the shock at the time of shifting based on the second shift pattern can also be reduced as in the case of the shifting based on the first shift pattern.
[0043]
In any of the above-described embodiments, a shift pattern in which all shift lines are shifted to the high vehicle speed side as shown in FIG. 3B is prepared as the second shift pattern of the low gear selection tendency. Alternatively, a shift pattern in which the highest speed stage (fourth speed in FIG. 3) is not selected may be used as the second shift pattern.
By the way, when the shift pattern in which the highest speed stage is not selected is changed to the second shift pattern, lockup of the torque converter is prohibited at the first speed lower speed stage (third speed) than the highest speed stage. Thus, it is better to satisfy the requirement that the shift shock reduction amount should be increased while the second shift pattern is selected.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a power train for a vehicle including a shift shock reducing device for an automatic transmission according to an embodiment of the present invention, together with its control system.
FIG. 2 is a flowchart showing a program executed by the transmission controller in the embodiment to select a shift pattern.
FIG. 3 illustrates two types of shift patterns,
(A) is a shift diagram showing a first commonly used shift pattern set with flat road running in mind;
(B) is a shift diagram showing a second shift pattern set in consideration of uphill roads and vehicle braking.
4 shows a shift shock mitigating action performed by a transmission controller and an engine controller in the control system shown in FIG.
(a) is an operation time chart of the shift shock mitigating action while the normal first shift pattern is selected;
(b) is an operation time chart of the shift shock reduction action while the second shift pattern is selected.
FIG. 5 shows a change characteristic of a line pressure at the time of shift determined for reducing a shift shock,
(a) is a change characteristic diagram of the line pressure during shifting while the normal first shift pattern is selected;
FIG. 6B is a change characteristic diagram of the line pressure characteristic during shift while the second shift pattern is selected.
[Explanation of symbols]
1 Engine (Power source)
2 Automatic transmission 3 Engine controller 4 Control valve 5 Shift solenoid 6 Shift solenoid 7 Line pressure solenoid 8 Transmission controller
11 Throttle opening sensor
12 Vehicle speed sensor
13 Transmission input rotation sensor
14 Navigation system
15 Brake fluid pressure sensor

Claims (6)

A first shift pattern that is normally used and a second shift pattern in which a shift occurs under an operating condition different from the first shift pattern is automatically selected according to the operating condition, and the selected shift pattern In an automatic transmission that performs shifting by switching engagement of friction elements based on
An automatic transmission characterized in that an operation amount for reducing a shift shock occurring at the time of shifting is made larger at the time of shifting based on the second shifting pattern than at the time of shifting based on the first shifting pattern. Gearshift shock reduction device.   The shift shock is reduced by reducing the torque of the power source in the preceding stage of the automatic transmission during shifting, and the amount of decrease in the power source torque is determined during shifting based on the first shift pattern. A shift shock reduction device for an automatic transmission, wherein the shift shock reduction device is configured to be larger at the time of shifting based on the second shift pattern.   3. The shift shock is reduced by reducing the engagement pressure of the friction element during shifting, and the amount of decrease in the engagement pressure is less than that during shifting based on the first shift pattern. A shift shock reduction device for an automatic transmission, wherein the shift shock reduction device is configured to increase during a shift based on a second shift pattern.   3. The shift shock is reduced by transiently controlling the engagement pressure of the friction element so that the input / output rotation speed ratio or the input rotation speed of the automatic transmission changes at a predetermined change rate during shifting. None, a shift shock reducing device for an automatic transmission, wherein the predetermined rate of change is configured to be smaller during a shift based on the second shift pattern than during a shift based on the first shift pattern.   5. The method according to claim 1, wherein the selection is switched from the first shift pattern to the second shift pattern when the road surface gradient is switched to an upward gradient greater than or equal to the set value, and the second shift pattern is changed to the first shift pattern. A shift shock reducing device for an automatic transmission, characterized in that a shift pattern is more likely to select a lower speed than the pattern.   5. The method according to claim 1, wherein selection is switched from the first shift pattern to the second shift pattern when the vehicle is in a braking state equal to or higher than a set value, and the second shift pattern is changed to the first shift pattern. A shift shock mitigation device for an automatic transmission, characterized in that the shift pattern tends to select a lower speed stage.

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