JP4016562B2 - Shift control device for continuously variable transmission for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device for a continuously variable transmission for a vehicle, and more particularly to a shift control device that performs appropriate shift control even when a rotation speed sensor fails.
[0002]
[Prior art]
2. Description of the Related Art A vehicle in which a continuously variable transmission is disposed on a power transmission path between a driving power source and driving wheels is known. Such variable speed control of the continuously variable transmission is generally performed in accordance with a shift condition such as a map determined in advance using the driver's output request amount such as an accelerator operation amount and the vehicle speed as parameters. Is normally determined so that the gear ratio (= input side rotational speed / output side rotational speed) increases as the required output amount increases and the vehicle speed decreases. In addition, the input side rotational speed of the continuously variable transmission is detected and the transmission control of the continuously variable transmission is performed so as to achieve a predetermined gear ratio, but in case the rotational speed sensor fails It is considered to provide a plurality of rotational speed sensors. The apparatus described in Japanese Patent Laid-Open No. 10-9381 is an example, and the input side rotational speed and the output side rotational speed of the continuously variable transmission are detected by a pair of rotational speed sensors, respectively, and the detected values are different. Is determined to be abnormal, a failure determination is made by determining the abnormal rotational speed based on the normal rotational speed and the gear ratio estimated from the speed change step motor, and one of the abnormal rotational speed sensors. Is identified as a failure.
[0003]
[Problems to be solved by the invention]
However, if one of the pair of rotation speed sensors is identified as described above, the shift control between them is not properly performed, and the engine rotation speed is temporarily increased by downshifting or the traveling stability is stabilized. There was a possibility that the performance was impaired. In other words, the failure of the rotational speed sensor is often due to disconnection, but when the input side rotational speed sensor wiring is disconnected, the input side rotational speed becomes 0, so that the input side rotational speed is increased continuously. The transmission is suddenly downshifted.
[0004]
In addition, the gear ratio other than means for estimating the gear ratio based on the input-side rotational speed and the output-side rotational speed, such as when the input-side rotational speed is matched with the target rotational speed to perform gear-feedback control. If the means for estimating is not provided, the failure determination itself of the rotational speed sensor cannot be performed, so that appropriate shift control cannot be performed. That is, since the gear ratio is the input side rotational speed / output side rotational speed, if the gear ratio is known, the input side rotational speed can be obtained by calculation from the vehicle speed or the like (output side rotational speed), but the gear ratio is not known. Since the input side rotational speed cannot be detected by a device other than the rotational speed sensor, the rotational speed sensor cannot be determined to be faulty.
[0005]
The present invention has been made against the background of the above circumstances, and the object of the present invention is to always carry out appropriate shift control regardless of the failure of the rotation speed sensor even when a means for estimating the gear ratio is not provided. There is in doing so.
[0006]
[Means for Solving the Problems]
In order to achieve this object, the first aspect of the present invention detects the input side rotational speed of a continuously variable transmission disposed in a power transmission path between a driving power source and driving wheels and detects the continuously variable transmission. In a shift control device that performs shift control of a machine, (a) a pair of rotation speed sensors that detect the input side rotation speed, and (b) an input side rotation speed detected by one of the pair of rotation speed sensors in advance. Selection means for subtracting the set value determined and selecting the larger value compared with the input side rotational speed detected by the other rotational speed sensor , and (c) selected by the selection means The shift control is performed using the input-side rotation speed that has been set.
[0007]
According to a second aspect of the present invention, in the transmission control device for a continuously variable transmission for a vehicle according to the first aspect of the invention, the pair of rotational speed sensors is an input member rotational speed sensor that detects a rotational speed of an input side rotational member of the continuously variable transmission. And a turbine rotation speed sensor for detecting a turbine rotation speed of a torque converter disposed between the continuously variable transmission and the power source.
[0008]
【The invention's effect】
In such a shift control device, a predetermined set value is subtracted from the input side rotational speed detected by one of the pair of rotational speed sensors and compared with the input side rotational speed detected by the other rotational speed sensor. Then, since the shift control is performed using the larger value, even if any of the rotation speed sensors fails, proper shift control is performed without performing the fail determination. In other words, failure of the rotation speed sensor is often due to disconnection, and the possibility that the rotation speed will increase due to the failure is small.Therefore, the larger value is likely to match the actual input rotation speed, but it may be due to noise or the like. Even if the detection value of the rotation speed sensor becomes high rotation and shift control is performed based on the detection value, the continuously variable transmission is shifted to the upshift side, so the running is stable compared to a sudden downshift. The influence on the sex and the power source is small. In addition, since no fail determination is performed, no means for estimating the gear ratio is required. For example, the continuously variable transmission is electrically feedback controlled so that the input side rotational speed matches the target rotational speed, and the speed control is performed. The present invention is also suitably applied to
Also, since a predetermined set value is subtracted from the input side rotational speed detected by one rotational speed sensor and compared with the input side rotational speed detected by the other rotational speed sensor, at least If the other rotational speed sensor is normal, the shift control is performed using the input side rotational speed detected by the other rotational speed sensor, regardless of whether one rotational speed sensor is normal. The shift control is stabilized.
[0009]
In the second invention, since the input member rotational speed sensor and the turbine rotational speed sensor are used as the pair of rotational speed sensors, the torque converter is compared with a case where a power source rotational speed sensor such as an engine rotational speed sensor is used. Therefore, any sensor can detect the input side rotational speed with high accuracy, and high reliability can be obtained.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention obtains the target rotational speed on the input side based on the driving state such as the vehicle speed (for example, the output side rotational speed of the continuously variable transmission) and the driver's requested output amount, and the actual input side rotational speed is the target rotational speed. The present invention is preferably applied to a shift control device that electrically feedback-controls a continuously variable transmission so as to match the speed. However, an actual transmission ratio is obtained by detecting an input side rotational speed and an output side rotational speed, respectively. The present invention is applied to various speed change control devices such as when controlling a continuously variable transmission so that the speed ratio becomes a target speed ratio. The detection method for detecting the output side rotational speed is determined as appropriate, and the detection value of the highest rotational speed may be adopted using a plurality of rotational speed sensors as in the present invention, or a fail determination is performed. A normal value may be identified. Alternatively, only a single rotational speed sensor may be used. In implementing the present invention, a failure determination may be performed by performing fail determination of a plurality of rotational speed sensors that detect the input side rotational speed separately from the shift control.
[0011]
Selection means, usually the so detected value of the other rotational speed sensor is selected, configured to compare by subtracting only setting value set in advance from one of the detected value of the rotational speed sensor. It is desirable to set the setting value in consideration of the detection accuracy so that the detection value of the other rotation speed sensor is always selected regardless of the detection error of the rotation speed sensor, but the other rotation speed sensor fails. For example, a value of 100 rpm or less, preferably 50 rpm or less is appropriate so that there is no problem even when the shift control is performed using the rotation speed obtained by subtracting the set value from the detection value of one of the rotation speed sensors. However, when the other rotation speed sensor fails, the shift control can be performed using the detection value of one rotation speed sensor before the set value is subtracted. Further, a predetermined ratio such as 1% to 5% of the detected value may be subtracted as a set value.
[0012]
In the second invention, an input member rotation speed sensor and a turbine rotation speed sensor are used as a pair of rotation speed sensors for detecting the input side rotation speed. In implementing the first invention, for example, a lockup provided in a torque converter is used. When the input-side rotating member is directly connected to the power source, for example, when the clutch is engaged, a sensor that detects the power source rotating speed can be used. A rotational speed sensor that detects rotational speeds of various members having the same or predetermined relationship can be employed.
[0013]
As a driving power source, an internal combustion engine such as a gasoline engine or a diesel engine that operates by combustion of fuel, or an electric motor that operates by electric energy is preferably used, and includes both the internal combustion engine and the electric motor. Also good. When using an internal combustion engine, it is desirable to dispose a fluid coupling such as a torque converter or a frictional start clutch that can continuously control the transmission torque between the continuously variable transmission and the like. This is not always necessary for hybrid vehicles that start off. As the continuously variable transmission, various transmissions such as a belt type continuously variable transmission and a toroidal type continuously variable transmission can be adopted.
[0014]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a skeleton diagram of a vehicle drive device 10 to which the present invention is applied. The vehicle drive device 10 is of a horizontal type and is suitably employed in an FF (front engine / front drive) type vehicle, and includes an engine 12 as an internal combustion engine used as a driving power source. The output of the engine 12 is transmitted from the torque converter 14 to the differential gear device 22 via the forward / reverse switching device 16, the belt-type continuously variable transmission (CVT) 18, and the reduction gear 20, and the left and right drive wheels 24L, 24R. Distributed to.
[0015]
The torque converter 14 includes a pump impeller 14p connected to the crankshaft of the engine 12 and a turbine impeller 14t connected to the forward / reverse switching device 16 via a turbine shaft 34, and transmits power through a fluid. Is supposed to do. Further, a lock-up clutch 26 is provided between the pump impeller 14p and the turbine impeller 14t so that they can be integrally connected to rotate integrally.
[0016]
The forward / reverse switching device 16 is composed of a double pinion type planetary gear device. The turbine shaft 34 of the torque converter 14 is connected to the sun gear 16s, and the input shaft 36 of the continuously variable transmission 18 is connected to the carrier 16c. ing. When the clutch 38 disposed between the carrier 16c and the sun gear 16s is engaged, the forward / reverse switching device 16 is rotated integrally, and the turbine shaft 34 is directly connected to the input shaft 36 to drive in the forward direction. The force is transmitted to the drive wheels 24R and 24L. When the brake 40 disposed between the ring gear 16r and the housing is engaged and the clutch 38 is released, the input shaft 36 is rotated in the reverse direction with respect to the turbine shaft 34 to drive in the reverse direction. The force is transmitted to the drive wheels 24R and 24L.
[0017]
The continuously variable transmission 18 includes an input-side variable pulley 42 having a variable effective diameter provided on the input shaft 36, an output-side variable pulley 46 having a variable effective diameter provided on the output shaft 44, and a variable thereof. A transmission belt 48 wound around pulleys 42 and 46 is provided. The variable pulleys 42 and 46 each have a variable V groove width, and the hydraulic pressure applied to the input side variable pulley 42 is controlled by, for example, the shift control circuit 50 shown in FIG. The engagement diameter (effective diameter) of 48 is changed, and the gear ratio γ (= input-side rotational speed NIN / output-side rotational speed NOUT) is continuously changed.
[0018]
The shift control circuit 50 of FIG. 3 includes an upshift electromagnetic valve 52 and a flow control valve 54 that reduce the transmission ratio γ, and a downshift electromagnetic valve 56 and a flow control valve 58 that increase the transmission ratio γ. ing. This shift control circuit 50 is the same as that described in Japanese Patent Laid-Open No. 11-182657, and when the upshift electromagnetic valve 52 is duty-controlled by the shift controller 60 (see FIG. 2), the modulator pressure PM is reduced. The reduced predetermined control pressure is output to the flow control valve 54, and the line pressure PL adjusted in accordance with the control pressure is supplied to the input side variable pulley 42, so that the V groove width becomes narrower. The gear ratio γ is reduced. When the downshift electromagnetic valve 56 is duty-controlled by the speed change controller 60, a predetermined control pressure obtained by reducing the modulator pressure PM is output to the flow control valve 58, and a drain port corresponding to the control pressure is output. By opening, the hydraulic oil in the input side variable pulley 42 is drained at a predetermined flow rate, the V groove width is widened, and the speed ratio γ is increased. Note that the hydraulic pressure of the output side variable pulley 46 is pressure-controlled so as to obtain a predetermined belt tension according to, for example, a transmission torque.
[0019]
The shift controller 60 shown in FIG. 2 is configured to include a microcomputer, and performs signal processing according to a program stored in advance in the ROM while utilizing the temporary storage function of the RAM, thereby controlling the shift of the continuously variable transmission 18. Functionally, NINT calculation means 62, NIN selection means 64, comparison means 65, and feedback control means 66 are provided. The speed change controller 60 constitutes a main part of the speed change control device, and the NIN selection means 64 corresponds to the selection means.
[0020]
The NINT calculation means 62 is supplied with signals representing the accelerator pedal operation amount θ _ACC and the vehicle speed V (specifically, the rotational speed NOUT of the output shaft 44) from the accelerator operation amount sensor 68 and the vehicle speed sensor 70. The target rotational speed NINT, which is the target value of the input-side rotational speed NIN, is calculated according to the shift conditions determined by using the accelerator operation amount θ _ACC and the vehicle speed V, which are driving states of the vehicle, as parameters. For example, as shown in FIG. 4, the speed change condition is determined by a data map, an arithmetic expression, or the like so that a target rotational speed NINT that sets a larger speed ratio γ as the vehicle speed V is smaller and the accelerator operation amount θ _ACC is larger is set. And stored in advance in a storage device such as a ROM. Since the vehicle speed V corresponds to the output side rotational speed NOUT, the target rotational speed NINT, which is the target value of the input side rotational speed NIN, corresponds to the target speed ratio, and the minimum speed ratio γmin and the maximum speed ratio γmax of the continuously variable transmission 18. It is set within the range. The accelerator operation amount θ _ACC corresponds to the output request amount of the driver.
[0021]
The NIN selection means 64 includes a signal representing the input member rotational speed NINMS and the turbine rotational speed NT from the input member rotational speed sensor 72 and the turbine rotational speed sensor 74 arranged as a plurality of rotational speed sensors for detecting the input side rotational speed. Is selected, and the input side rotational speed NIN used for the shift control is selected according to the flowchart shown in FIG. Specifically, the input member rotational speed sensor 72 and the turbine rotational speed sensor 74 are arranged so as to detect the rotational speeds of the input side variable pulley 42 and the clutch 38 as shown in FIG. Instead of the pulley 42, the rotational speed of the input shaft 36 and the carrier 16c may be detected, or the rotational speed of the turbine shaft 34 may be detected instead of the clutch 38. Further, when the lockup clutch 26 is engaged, the rotational speed of the engine 12 can be used for the shift control. In this embodiment, the input side variable pulley 42 corresponds to the input side rotating member.
[0022]
In step S1 of FIG. 5, a signal representing the input member rotational speed NINMS is read from the input member rotational speed sensor 72, and in step S2, a signal representing the turbine rotational speed NT is read from the turbine rotational speed sensor 74. In step S3, a predetermined set value α is subtracted from the turbine rotation speed NT to calculate the turbine rotation speed NTMS, and in step S4, the turbine rotation speed NTMS and the input member rotation speed NINMS are compared. If NINMS ≧ NTMS, the input side rotational speed NIN = NINMS is set in step S5, and if NINMS <NTMS, the input side rotational speed NIN = NTMS is set in step S6. That is, the larger value of the input member rotational speed NINMS and the turbine rotational speed NTMS is set as the input side rotational speed NIN.
[0023]
Here, since the turbine rotational speed NTMS is a value obtained by subtracting the set value α from the actual turbine rotational speed NT, normally, NINMS ≧ NTMS, and the input member rotational speed NINMS is set to the input side rotational speed NIN in step S5. However, since the input member rotation speed NINMS is the rotation speed of the input-side variable pulley 42 that is a component of the continuously variable transmission 18, it is most suitable for use in the shift control of the continuously variable transmission 18. The set value α is set in consideration of the detection accuracy and the like so that the detection value NINMS of the input member rotation speed sensor 72 is always selected regardless of the detection errors of the rotation speed sensors 72 and 74. For example, a value of about 50 rpm is determined so that there is no problem even when the input member rotation speed sensor 72 fails and gear shift control is performed using the turbine rotation speed NTMS. For this reason, if the input member rotational speed sensor 72 fails and becomes NINMS <NTMS, even if the turbine rotational speed NTMS is used as the input side rotational speed NIN, there is a possibility that the transmission control of the continuously variable transmission 18 may be hindered. There is no. However, in step S6, the turbine rotational speed NT before subtracting the set value α may be set to the input side rotational speed NIN. In that case, the set value α is compared within a range that does not interfere with the shift control. Large value can be set.
[0024]
Further, since the forward / reverse switching device 16 rotates integrally during forward travel, the turbine rotational speed NT basically matches the input member rotational speed NINMS and can be used as it is. However, during reverse travel, the teeth of the planetary gear device can be used. When the number ratio (= the number of teeth of the sun gear 16s / the number of teeth of the ring gear 16r) is ρ, the gear is shifted at a gear ratio of (α) / α | (= NT / NINMS). For this reason, in step S2, the turbine rotational speed NT is corrected by being divided by the gear ratio | (α-1) / α | during reverse travel. However, since the gear ratio is 1 when α = 0.5, the turbine rotational speed NT can be used as it is.
[0025]
Returning to FIG. 2, the comparing means 65 calculates a speed deviation ΔNIN between the target rotational speed NINT supplied from the NINT calculating means 62 and the input-side rotational speed NIN supplied from the NIN selecting means 64, and feedback control means. 66. The feedback control means 66 performs feedback control of the electromagnetic valves 52 and 56 of the speed change control circuit 50 so that the speed deviation ΔNIN becomes 0, and the actual input side rotational speed NIN substantially matches the target rotational speed NINT. It is done. Specifically, if at least the input member rotation speed sensor 72 is normal, the shift control is performed so that the input member rotation speed NINMS substantially matches the target rotation speed NINT regardless of whether the turbine rotation speed sensor 74 is normal. Is done. That is, when the turbine rotational speed sensor 74 fails due to disconnection or the like, the signal output is normally 0 and the state of NINMS ≧ NTMS is maintained, so the input member rotational speed NINMS is equal to the input side rotational speed NIN. It is done. When the input member rotational speed sensor 72 is broken due to disconnection or the like and the signal output becomes 0, the turbine rotational speed NTMS obtained by subtracting the set value α from the detected value NT of the turbine rotational speed sensor 74 is the target rotational speed. Shift control is performed so as to substantially match NINT. Thereby, even if the rotation speed sensor 72 or 74 breaks down, the speed ratio γ of the continuously variable transmission 18 is appropriately controlled according to the accelerator operation amount θ _ACC and the vehicle speed V.
[0026]
As described above, in this embodiment, the pair of input member rotational speed sensors 72 and the turbine rotational speed sensor 74 are disposed as rotational speed sensors for detecting the input side rotational speed NIN, and the input member rotational speed NINMS detected by them. And the larger value of the turbine rotational speed NTMS is used as the input-side rotational speed NIN, so that even if one of the rotational speed sensors 72 and 74 breaks down, it is appropriate without performing a fail determination. Shift control is performed.
[0027]
That is, failure of the rotation speed sensors 72 and 74 is often caused by disconnection, and the possibility that the rotation speeds NINMS and NTMS will increase due to the failure is small. Therefore, there is a high probability that the larger value coincides with the actual input rotation speed. On the other hand, even if the detected values NINMS and NTMS of the rotation speed sensors 72 and 74 become high due to noise or the like and the shift control is performed based on the detected values NINMS or NTMS, the continuously variable transmission 18 is upshifted. Since the gear is shifted to the side, the influence on the running stability and the engine 12 is small compared to the sudden downshift.
[0028]
In this embodiment, since the turbine rotation speed NTMS obtained by subtracting the predetermined set value α from the actual detection value NT of the turbine rotation speed sensor 74 is compared with the input member rotation speed NINMS, at least the input If the member rotational speed sensor 72 is normal, the input member rotational speed NINMS, which is a detection value of the input member rotational speed sensor 72, matches the target rotational speed NINT regardless of whether the turbine rotational speed sensor 74 is normal. Thus, the shift control is performed, and the shift control is stabilized. In particular, the input member rotational speed sensor 72 is arranged so as to detect the rotational speed of the input side variable pulley 42 itself, which is a component of the continuously variable transmission 18, and therefore the input side rotation of the continuously variable transmission 18. The speed is detected with high accuracy and excellent control accuracy is obtained.
[0029]
Further, since it is not necessary to make a failure determination as to which of the rotation speed sensors 72 and 74 is a failure, there is no need for a means for estimating the speed ratio γ as in the fail-safe device described in Japanese Patent Laid-Open No. 10-9381. Thus, even when the speed change control is performed by electrically feedback controlling the continuously variable transmission 18 so that the input side rotational speed NIN matches the target rotational speed NINT as in this embodiment, the rotational speed sensor 72 or Regardless of the failure of 74, the shift control can be properly performed.
[0030]
Further, since the input member rotational speed sensor 72 and the turbine rotational speed sensor 74 are used as a plurality of rotational speed sensors, for example, the rotational speed ratio of the torque converter 14 is considered in comparison with the case where the engine rotational speed sensor is used. Any of the rotational speed sensors 72 and 74 can detect the input side rotational speed of the continuously variable transmission 18 with high accuracy and can obtain high reliability.
[0031]
As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added the various change and improvement based on the knowledge of those skilled in the art. Can do.
[Brief description of the drawings]
FIG. 1 is a skeleton diagram of a vehicle drive device to which the present invention is applied.
2 is a block diagram illustrating a transmission control device for a continuously variable transmission in the vehicle drive device of FIG. 1; FIG.
FIG. 3 is a hydraulic circuit diagram specifically showing an example of a shift control circuit in FIG. 2;
4 is a diagram showing an example of a speed change condition used when the NINT calculation means of FIG. 2 calculates a target rotational speed NINT. FIG.
FIG. 5 is a flowchart illustrating specific processing contents of the NIN selection unit in FIG. 2;
[Explanation of symbols]
12: Engine (power source) 14: Torque converter 18: Continuously variable transmission 42: Input-side variable pulley (input-side rotating member) 60: Shift controller (shift control device) 64: NIN selection means (selection means) 72: Input member rotational speed sensor (the other rotational speed sensor) 74: Turbine rotational speed sensor (one rotational speed sensor) NIN: Input side rotational speed NINT: Target rotational speed NINMS: Input member rotational speed NT, NTMS: Turbine rotational speed α : Setting value

Claims (2)

In a shift control device that detects the input side rotational speed of a continuously variable transmission disposed in a power transmission path between a driving power source and driving wheels and performs shift control of the continuously variable transmission,
A pair of rotational speed sensors for detecting the input side rotational speed;
A predetermined setting value is subtracted from the input side rotational speed detected by one of the pair of rotational speed sensors, and the larger value is compared with the input side rotational speed detected by the other rotational speed sensor. A selection means to select;
A shift control apparatus for a continuously variable transmission for a vehicle, wherein the shift control is performed using an input side rotational speed selected by the selection means. The pair of rotation speed sensors includes an input member rotation speed sensor that detects a rotation speed of an input side rotation member of the continuously variable transmission, and a torque converter disposed between the continuously variable transmission and the power source. The shift control device for a continuously variable transmission for a vehicle according to claim 1, wherein the turbine rotation speed sensor detects a turbine rotation speed of the vehicle.

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