JP2004116605A - Automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent excessive load from being applied on an automatic transmission at an abnormal operation by determining an error in an inhibitor switch. <P>SOLUTION: In this automatic transmission including an inhibitor switch 22 for outputting a range signal from the conducting status of each of a plurality of switches operated in accordance with a shift lever and a control device 20 for determining a shift range based on the on/off pattern of the switches corresponding to a normal range and the on/off pattern of the switches corresponding to an intermediate range placed between ranges, the control device 20 controls the shift range as the normal range immediately before when the intermediate range is determined, and conducts a failure diagnosis of the inhibitor switch 22. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in an automatic transmission having an inhibitor switch.
[0002]
[Prior art]
An automatic transmission mounted on a vehicle is provided with an inhibitor switch for detecting a shift range that determines a traveling mode, an example of which is shown in FIG. The inhibitor switch is a linear inhibitor switch that detects a range state from ON / OFF states of four switches, and is arranged between a travel range pattern that determines a travel mode and a travel range without determining a travel range. And a pattern for an intermediate range having a role of a dead zone between ranges. In this example, the inhibitor switches are set so that the ON / OFF patterns of the switches between adjacent ranges are different by only one. Here, the running range is used to indicate a difference from the intermediate range, and includes a P and N range in addition to a range in which the vehicle runs, such as a D and R range. In other words, it usually means a range that the driver consciously selects.
[0003]
In the intermediate range, the previous range determination is held. That is, in the case of P → P (R), the determination of the traveling range P is maintained in the intermediate range P (R). Therefore, even when one of the four switches of the inhibitor switch is disconnected or short-circuited, if the select lever is set to the travel range, it is determined that the intermediate range is the immediately preceding intermediate range, and the range is determined immediately before. The travel range is controlled by the travel range maintained by the intermediate range, and is not erroneously determined by another travel range.
[0004]
[Problems to be solved by the invention]
However, when a part of the inhibitor switch is disconnected or short-circuited and the driving range is selected from the P or N range to another driving range, the selected driving range is determined as the intermediate range passed at the time of selection, and the range is determined. The judgment is maintained in the P or N range.
[0005]
When the INH SW4 in FIG. 3 is disconnected, even if the signal is selected from the N range to the D range via the intermediate range N (D), the signal remains as N (D), so that the range determination is performed. Will be in the N range.
[0006]
In this case, the range determination is the N range despite the fact that the range is actually the driving range (D range). Therefore, the clutch of the forward / reverse switching mechanism is engaged without adjusting the clutch pressure, and V In the case of a belt-type continuously variable transmission, an excessive input is applied to the V-belt, and the durability of the unit deteriorates. The same applies to the case of a racing select in which the accelerator pedal is depressed to select another travel range from the P or N range.
[0007]
In view of the above, the present invention has been made in view of the above-described problems, and when an ON / OFF pattern of an inhibitor switch is detected in an intermediate range or an abnormal pattern that is not in a predetermined pattern, a clutch capacity and an engine torque of a forward / reverse switching mechanism are detected. Another object is to limit the engine rotation speed and improve the durability of the automatic transmission unit.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an inhibitor switch that outputs a range signal from a conduction state of a plurality of switches responding to a shift lever, and an on / off pattern of the switch corresponding to a normal range and a range provided between each range based on a detected range signal. And a control device that determines a shift range based on the on / off pattern of the switch corresponding to the intermediate range that has been set, when the intermediate range is determined, the control device immediately shifts the shift range. And the fault diagnosis of the inhibitor switch is performed.
[0009]
According to a second aspect of the present invention, there is provided an inhibitor switch that outputs a range signal from a conduction state of a plurality of switches responding to a shift lever, and an on / off pattern of a switch corresponding to a normal range and each of the ranges based on a detected range signal. A control device that determines a shift range based on an on / off pattern of a switch corresponding to the intermediate range, wherein the control device detects an abnormal on / off pattern that does not correspond to the normal range and the intermediate range. Next, a failure diagnosis of the inhibitor switch is performed.
[0010]
In a third aspect based on the first or second aspect, the control device performs protection control of the automatic transmission when an on / off pattern of a switch corresponding to an intermediate range or the abnormal on / off pattern is detected by an inhibitor switch. carry out.
[0011]
In a fourth aspect based on the second or third aspect, the detection time of the abnormal on / off pattern is measured, and when the duration is longer than a predetermined time, it is determined that the inhibitor switch has failed.
[0012]
In a fifth aspect based on the fourth aspect, when the inhibitor switch failure is determined, the protection control for the automatic transmission is continued until the ignition switch of the vehicle is turned off.
[0013]
In a sixth aspect based on the third or fifth aspect, the automatic transmission includes a forward / reverse switching mechanism including a forward / reverse clutch, and the protection control of the automatic transmission includes a clutch of the forward / reverse switching mechanism. Limit the fastening pressure of
[0014]
In a seventh aspect based on the third or fifth aspect, the protection control of the automatic transmission limits the output torque of the engine.
[0015]
In an eighth aspect based on the third or fifth aspect, the protection control for the automatic transmission limits the output rotation speed of the engine.
[0016]
【The invention's effect】
Therefore, in the first and second inventions, when the control device determines the intermediate range, the control device controls the shift range as the immediately preceding normal range, diagnoses the failure of the inhibitor switch, and handles the normal range and the intermediate range. When an abnormal ON / OFF pattern is detected, the failure of the inhibitor switch is diagnosed, so that the abnormality of the inhibitor switch can be quickly determined.
[0017]
In the third invention, the control device performs the protection control of the automatic transmission when detecting the ON / OFF pattern of the switch corresponding to the intermediate range or the abnormal ON / OFF pattern from the inhibitor switch. This prevents input from acting and improves the durability of the automatic transmission.
[0018]
According to the fourth aspect, the detection time of the abnormal ON / OFF pattern is measured, and when the duration time is longer than a predetermined time, it is determined that the inhibitor switch has failed. Can be.
[0019]
In the fifth invention, when the inhibitor switch failure is determined, the protection control of the automatic transmission is continued until the ignition switch of the vehicle is turned off, so that the ON / OFF pattern of another normal range is detected at the normal range position. Even in such a case, since the protection control of the automatic transmission is performed, an excessive input is not applied to the automatic transmission.
[0020]
In the sixth aspect, the automatic transmission includes a forward / reverse switching mechanism having forward and reverse clutches. The protection control of the automatic transmission is performed by automatically controlling the engagement pressure of the clutch of the forward / reverse switching mechanism. An excessive input does not act on the transmission, and the durability of the automatic transmission can be improved.
[0021]
In a seventh aspect based on the third or fifth aspect, the protection control of the automatic transmission limits the output torque of the engine, thereby suppressing the input torque to the automatic transmission and improving the durability of the automatic transmission. I do.
[0022]
In an eighth aspect based on the third or fifth aspect, the protection control of the automatic transmission limits the output rotation speed of the engine, so that the input rotation speed to the automatic transmission is suppressed, and the durability of the automatic transmission is improved. To improve.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
[0024]
FIG. 1 is a schematic configuration diagram of a V-belt type continuously variable transmission (automatic transmission).
[0025]
In FIG. 1, the automatic transmission mainly includes a forward / reverse switching mechanism 4 connected to the engine 1 and a continuously variable transmission 5 connected to an output shaft of the forward / reverse switching mechanism 4. Has a primary pulley 10 on the input shaft side as a pair of variable pulleys, and a secondary pulley 11 connected to the output shaft 13, and the pair of variable pulleys 10 and 11 are connected by a V-belt 12. The output shaft 13 is connected to the driving wheels 14 via idler gears and differential gears. Further, a starting element (not shown) such as a torque converter is interposed between the input side of the forward / reverse switching mechanism 4 and the engine 1.
[0026]
The forward / reverse switching mechanism 4 includes a planetary gear 40 for switching the power transmission path between the engine 1 and the primary pulley 10, a forward clutch 41, and a reverse brake 42. When the vehicle is moving forward, the forward clutch 41 is engaged, and the vehicle is moved backward. At times, the reverse brake 42 is engaged, and in the neutral position (neutral or parking), both the forward clutch 41 and the reverse brake 42 are released.
[0027]
The engagement state of the forward clutch 41 and the reverse brake 42 is controlled by the clutch pressure adjusting device 30 that supplies the forward clutch pressure and the reverse brake pressure in response to a command from the control unit 20.
[0028]
The clutch pressure adjusting device 30 adjusts the forward clutch pressure and the reverse brake pressure using the hydraulic pressure from the hydraulic pump 15 as a source pressure. The hydraulic pump 15 is connected to an input side or the like of the forward / reverse switching mechanism 4 and driven by the engine 1.
[0029]
The control unit 20 is based on a vehicle speed signal from a vehicle speed sensor 21, a range signal from an inhibitor switch 22 responsive to a shift lever, an engine rotation speed signal from the engine 1 (or an engine control device), and other driving states and driving operations. , And determines a hydraulic pressure command value and issues a command to the clutch pressure adjusting device 30. Note that the inhibitor switch 22 shows an example of selecting one of forward (D range), neutral position = neutral (N range), and backward (R range).
[0030]
The clutch pressure adjusting device 30 adjusts the forward clutch pressure and the reverse brake pressure in accordance with the hydraulic pressure command value to engage or release the forward clutch 41 and the reverse brake 42.
[0031]
The forward clutch 41 and the reverse brake 42 are exclusively engaged. During forward travel (range signal = D range), the forward clutch pressure is supplied to fasten the forward clutch 41 and the reverse brake pressure is connected to the drain. Then, the reverse brake 42 is released. At the time of reversing (range signal = R range), the forward clutch pressure is connected to the drain to release the forward clutch 41, while the reverse brake pressure is supplied to engage the reverse brake 42. At the neutral position (range signal = N range), the forward clutch pressure and the reverse brake pressure are connected to the drain, and both the forward clutch 41 and the reverse brake 42 are released.
[0032]
The gear ratio of the continuously variable transmission 5 and the contact frictional force of the V-belt are controlled by a hydraulic control unit (not shown) that responds to a command from the control unit 20.
[0033]
FIG. 2 is a flowchart showing an example of the inhibitor switch abnormality determination control and the automatic transmission protection control performed by the control unit 20, and is executed at a predetermined cycle (for example, several tens of milliseconds). Hereinafter, a case where the range is switched from N → N (D) → D will be described as an example.
[0034]
First, in step S1, the range signal of the inhibitor switch 22 is monitored, and in step 2, it is determined whether the pattern of the intermediate range N (D) is an abnormal pattern from the on / off pattern of FIG. In the case of an abnormal pattern, the process proceeds to step 3 and the counting of the determination timer is started. If the pattern is normal, the process proceeds to step 4.
[0035]
In step 5 following step 3, in order to protect the automatic transmission unit, at least one protection control of the pressures of the clutches 41 and 42, the engine rotation speed, and the engine output torque is performed. For example, in the control of the clutch pressure, a torque capacity smaller than the torque capacity generated by the allowable pressing of the V-belt is generated, and the control is performed with the clutch pressure necessary for traveling as a vehicle. When limiting the engine torque, the throttle valve opening, the fuel injection amount, and the like are set in consideration of the input torque to the V-belt. At this time, the inertia torque is considered as the input torque to the V-belt. Regarding the engine rotation speed, it is necessary to consider the rotation speed for the inertia in the engine rotation speed.
[0036]
Further, in step 6, it is determined whether or not the pattern is an abnormal pattern based on the count number of the determination timer. If the count number so far is equal to or more than a predetermined count number (time, for example, 2 to 5 seconds), it can be accurately determined that the abnormal pattern is not caused by noise, and the process proceeds to step 7 to determine that the abnormal pattern is present. If the count has not reached the predetermined count, the process returns to step 2. In step 8, the control for limiting the pressures of the clutches 41 and 42, the engine rotation speed, and the engine output torque, which is the unit protection control described above, is continued. This unit protection control is continued until the ignition switch is turned off.
[0037]
On the other hand, if no abnormal pattern is detected in step 2, after the determination timer is reset in step 4 (the reset of the timer in this case is such that the detection of the abnormal pattern ends without a predetermined time after the abnormal pattern is detected). Then, the process proceeds to step 9, where it is determined whether or not the pattern is an intermediate range N (D) based on the ON / OFF pattern of the inhibitor switch. If the pattern is in the middle range, the unit protection control described above is performed in step 10, and the process returns to step 9. The unit protection control is repeated until a running pattern other than the intermediate range is reached (the running pattern here includes a running range such as the D range as well as a pattern of the P and N ranges). When a pattern other than the intermediate range (for example, D range) is detected in step 9, the process proceeds to step 11, interrupts the unit protection control, determines in step 12 that the inhibitor switch 22 is normal, returns to step 1, and returns to step 1. repeat.
[0038]
Therefore, in the control device for an automatic transmission according to the present invention, the travel range for determining the travel mode (P, R, N, D, and L ranges in FIG. 3) and the travel range without determining the travel range are determined. An inhibitor switch disposed to detect an intermediate range having a role of a dead zone between ranges is provided.When the intermediate range is detected, control of the immediately preceding range is maintained, protection control of the automatic transmission is performed, and an inhibitor switch is provided. By performing the abnormality determination, it is possible to prevent the automatic transmission from breaking down even when the inhibitor switch is abnormal.
[0039]
In addition, even when the pattern for detecting the range of the inhibitor switch is an abnormal pattern, the protection control of the automatic transmission is performed and the abnormality determination of the inhibitor switch is performed, so that the automatic transmission fails even when the inhibitor switch is abnormal. Can be prevented.
[0040]
The protection control of the automatic transmission limits the engagement pressure of the clutch of the forward / reverse switching mechanism to a predetermined pressure. Therefore, when the inhibitor switch is abnormal, even if the travel range is selected from the P or N range to another travel range. Shock at the time of clutch engagement can be reduced, and durability of the V-belt can be improved.
[0041]
The predetermined pressure is a pressure that generates a torque capacity smaller than a torque capacity generated by pressing the V-belt and is larger than a clutch engagement pressure necessary for running of the vehicle.
[0042]
The protection control of the automatic transmission limits the output torque of the engine to a predetermined torque. Therefore, even when the inhibitor switch is abnormal, even if the racing selection is made from the P or N range to another driving range, the automatic transmission is protected. Machine unit failure can be prevented.
[0043]
The predetermined torque is a torque set in consideration of the output torque of the engine and the inertia torque.
[0044]
Further, the protection control of the automatic transmission limits the output rotation speed of the engine to a predetermined rotation speed. Therefore, when the inhibitor switch is abnormal, even if the racing selection is made from the P or N range to another driving range, Failure of the automatic transmission unit can be prevented.
[0045]
The predetermined rotation speed is a speed set in consideration of the output rotation speed of the engine and the rotation speed for inertia.
[0046]
When the ON / OFF pattern of the inhibitor switch is an abnormal pattern, the elapsed time is counted, and when the elapsed time is longer than a predetermined time, it is determined that the inhibitor switch is abnormal. By removing it, the failure of the inhibitor switch can be accurately determined.
[0047]
When the failure of the inhibitor switch is determined, the protection control of the automatic transmission is continued until the ignition switch is turned off, so that the inhibitor switch is abnormal due to the abnormality of the switch. Even when the on / off pattern is the same as the other ranges, fail-safe control of the automatic transmission can be performed, and the durability of the automatic transmission is not impaired.
[0048]
In the above-described embodiment, an example in which a V-belt type continuously variable transmission is used as the automatic transmission has been described. However, similar effects can be obtained when a planetary gear type or a toroidal type is used. .
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an automatic transmission according to an embodiment of the present invention.
FIG. 2 is a flowchart showing an example of inhibitor switch abnormality determination control performed by the control unit.
FIG. 3 is a schematic explanatory diagram of an inhibitor switch.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 4 Forward / reverse switching mechanism 5 Continuously variable transmission 10 Primary pulley 11 Secondary pulley 20 Control unit 30 Clutch pressure adjusting device

Claims (8)

An inhibitor switch that outputs a range signal from the conduction state of a plurality of switches that respond to the shift lever;
From the detected range signal, a control device that determines a shift range based on an on / off pattern of the switch corresponding to a normal range and an on / off pattern of the switch corresponding to an intermediate range provided between each range,
In an automatic transmission equipped with
An automatic transmission, wherein when the intermediate range is determined, the control device controls the shift range as the immediately preceding normal range and performs a failure diagnosis of the inhibitor switch. An inhibitor switch that outputs a range signal from the conduction state of a plurality of switches that respond to the shift lever;
From the detected range signal, a control device that determines a shift range based on an on / off pattern of the switch corresponding to a normal range and an on / off pattern of the switch corresponding to an intermediate range provided between each range,
In an automatic transmission equipped with
The automatic transmission according to claim 1, wherein the controller performs a failure diagnosis of the inhibitor switch when an abnormal on / off pattern not corresponding to the normal range and the intermediate range is detected. 3. The control device according to claim 1, wherein the control device performs protection control of the automatic transmission when an on / off pattern of the switch corresponding to an intermediate range or the abnormal on / off pattern is detected by an inhibitor switch. 4. Automatic transmission. 4. The automatic transmission according to claim 2, wherein a detection time of the abnormal on / off pattern is measured, and when the duration is equal to or longer than a predetermined time, it is determined that the inhibitor switch has failed. 5. The automatic transmission according to claim 4, wherein when the inhibitor switch failure is determined, the protection control of the automatic transmission is continued until the ignition switch of the vehicle is turned off. The automatic transmission includes a forward / reverse switching mechanism including forward and reverse clutches,
6. The automatic transmission according to claim 3, wherein the protection control for the automatic transmission limits the engagement pressure of the clutch of the forward / reverse switching mechanism. 6. The automatic transmission according to claim 3, wherein the protection control of the automatic transmission limits the output torque of the engine. 6. The automatic transmission according to claim 3, wherein the protection control of the automatic transmission limits an output rotation speed of the engine.

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