JP2004278664A - Control device for continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for accurately detecting sliding in a continuously variable transmission. <P>SOLUTION: A control device for a continuously variable transmission for detecting the sliding of a continuously variable transmission part based on a correlation coefficient k(i) of an input rotation speed Nin(i) to an output rotation speed Nout(i) with respect to the continuously variable transmission, comprises; a filter processing means (step S3) for filtering a detection signal of the correlation coefficient k(i); and a sliding detection means (steps S4, S6) for determining the sliding in the continuously variable transmission part based on a filter processing value k_hi(i) processed in the filter processing means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２９】
この相関係数ｋ（ｉ） は、入力軸回転速度Ｎｉｎ（ｉ） と出力軸回転速度Ｎｏｕｔ（ｉ）との相互の関係（例えば変速比γ）が一定していて変化がなければ“１”となり、いずれか一方の回転速度が低下もしくは増大することによって両者の回転速度の相互関係（例えば変速比γ）が変化すると、その過程で“１”より小さい値になる。
【００３０】
無段変速機１の入力軸回転速度Ｎｉｎ（ｉ） と出力軸回転速度Ｎｏｕｔ（ｉ）と（特に入力軸回転速度Ｎｉｎ（ｉ） ）は、ベルト２３の滑りが生じた場合に変化し、相互の関係が変化するが、変速比γを変化させた場合にも各回転速度Ｎｉｎ（ｉ） ，Ｎｏｕｔ（ｉ）の相互の関係が変化する。その滑りに起因する変化の態様と変速比γを変化させた場合の回転速度の変化の態様とが異なっているので、相関係数ｋ（ｉ） の変化がいずれによるものであるかを区別するために、相関係数ｋ（ｉ） の検出信号がフィルタ処理される（ステップＳ３）。このフィルタ処理は、一例としてハイパスフィルタ処理であって、その処理値ｋ＿ｈｉ（ｉ）が算出される。
【００３１】
図２には、加速中に滑りとアップシフトとが順に生じた場合の各回転速度Ｎｉｎ（ｉ），Ｎｏｕｔ（ｉ）、変速比γ、相関係数ｋ（ｉ）、そのハイパイフィルタ処理値ｋ＿ｈｉ（ｉ）の変化を模式的に示してある。図２から知られるように、滑りが生じると、各回転速度Ｎｉｎ（ｉ），Ｎｏｕｔ（ｉ）が瞬間的に変化し、これに合わせて変速比γが変化する。図２の例では、ダウンシフト側に変速比γが変化している。
【００３２】
そのため、各回転速度Ｎｉｎ（ｉ），Ｎｏｕｔ（ｉ）から求められる相関係数ｋ（ｉ） およびそのハイパスフィルタ処理値ｋ＿ｈｉ（ｉ）が瞬間的に大きく低下する。一方、アップシフトが生じると、入力軸回転速度Ｎｉｎ（ｉ） がある程度ゆっくり低下するので、それに伴って相関係数ｋ（ｉ）が低下する。その変化の速度は、変速比γの変化速度に対応しており、滑りに起因する変化の場合と比較してかなりゆっくりとしたものとなる。そのため、低周波域をカットするハイパスフィルタ処理をおこなった処理値ｋ＿ｈｉ（ｉ）は、変化するものの、その低下幅が小さいものにとどまる。
【００３３】
したがって上記のステップＳ３に続くステップＳ４では、ハイパスフィルタ処理値ｋ＿ｈｉ（ｉ）が予め定めたしきい値ｋｓｌｐ より小さいか否かが判断される。このしきい値ｋｓｌｐ を図２に併せて示してあり、その値は変速時の相関係数ｋ（ｉ） が到達するものの、そのハイパスフィルタ処理値ｋ＿ｈｉ（ｉ）は到達しない値である。
【００３４】
このステップＳ４で否定的に判断された場合には、滑りの判定が成立しないので、通常の制御が実行される（ステップＳ５）。この通常の制御は、例えば、平坦路の定常的な走行もしくは準定常的に走行時にベルト挟圧力を低下させる制御であり、また悪路を走行し、あるいは加減速度が大きいなどの非定常的な走行の場合に、挟圧力をライン圧程度に高くする制御である。
【００３５】
これに対してステップＳ４で肯定的に判断された場合には、ベルト滑りの判定がおこなわれる（ステップＳ６）。そして、それに対応した制御が実行される（ステップＳ７）。このステップＳ７での対応制御は、要は、無段変速機１に作用するトルクに対する伝達トルク容量を相対的に増大させる制御であり、例えば、ベルト挟圧力を増大させる制御である。これに替え、あるいは同時にエンジントルクを低下させる制御を実行してもよい。
【００３６】
したがって上述したこの発明に係る装置による制御によれば、相関係数ｋ（ｉ） を使用して無段変速部での滑りを検出するものの、その相関係数ｋ（ｉ） の検出信号に含まれている通常の変速に伴う変化成分を、ハイパスフィルタ処理によって除去し、そのハイパスフィルタ処理値ｋ＿ｈｉ（ｉ）に基づいて滑りを判定するので、正確な滑り判定もしくは検出をおこなうことができる。また、通常の変速に伴う前記相関係数ｋ（ｉ） が小さい値となるとしても、そのハイパスフィルタ処理値ｋ＿ｈｉ（ｉ）が大きくは低下しないので、滑り判定のための前記しきい値ｋｓｌｐ を“１”より僅かに小さい程度の比較的大きい値に設定することができ、その結果、相関係数ｋ（ｉ） のフィルタ処理値が僅かに低下する程度のいわゆる小さい滑りであっても検出することができ、この点でも滑りの検出精度が高くなる。
【００３７】
ベルト滑りが発生した場合、および変速が生じた場合のいずれであっても、入力軸回転速度Ｎｉｎ（ｉ） および出力軸回転数Ｎｏｕｔ（ｉ）が変化するから、上述した相関係数ｋ（ｉ） だけでなく、変速比γやその変化勾配Δγなどが変化する。そして、これらの変化の態様は、滑りに起因する場合と変速制御に起因する場合とでは異なっているので、いずれかの検出信号を、上述した具体例と同様にフィルタ処理することにより、滑りによる変化と変速による変化とに区別することができる。図３には、変速比勾配Δγを利用した例を模式的に示してある。
【００３８】
図３は、ベルト滑りが生じた場合および変速が開始された場合の変速比γ、変速比勾配Δγ、そのハイパスフィルタ処理値Δγ＿ｈｉ（ｉ）の変化を示してある。例えば加速中にベルト滑りが生じると、変速比γが一時的にダウンシフト側に増大する。それに伴って変速比勾配Δγが大小に脈動するように変化する。この場合、変速が生じていないので、ある程度長い時間幅での変速比γの変化が殆どなく、したがって検出された変速比勾配Δγは比較的高い周波数での変化となる。そのため、変速比勾配Δγをハイパスフィルタ処理しても特に除去される成分がないので、そのハイパスフィルタ処理値Δγ＿ｈｉ（ｉ）は変速比勾配Δγと同様な変化を示す。
【００３９】
これに対して変速制御によって変速比γが例えばダウンシフト側に増大した場合、変速ショックや動力の損失を防止するためにある程度ゆっくり変速をおこなうので、その変速比勾配Δγが小さく、かつその変化量も小さくなる。そして、その変速比勾配Δγの検出信号から低周波成分を除去するハイパスフィルタ処理をおこなうと、そのフィルタ処理値Δγ＿ｈｉ（ｉ）は小さい値となる。
【００４０】
したがって変速比勾配Δγのハイパスフィルタ処理値Δγ＿ｈｉ（ｉ）に基づくベルト滑りの判定しきい値Δγｓｌｐ として、変速時のフィルタ処理値を僅か上回る程度の小さい値を設定しておくことにより、ベルト滑りと変速とを区別することができる。すなわち、ベルト滑りの検出精度が向上するとともに、しきい値を小さくすることができることにより小さい滑りをも正確に検出することができる。
【００４１】
このような変速比勾配Δγおよびそのフィルタ処理値Δγ＿ｈｉ（ｉ）を利用したベルト滑りの判定は、例えば図１に示すフローチャートにおける相関係数ｋ（ｉ） およびそのハイパスフィルタ処理値ｋ＿ｈｉ（ｉ）ならびにそのしきい値ｋｓｌｐ を、それぞれ変速比勾配Δγおよびそのハイパスフィルタ処理値Δγ＿ｈｉ（ｉ）ならびにそのしきい値Δγｓｌｐ に置き換えたフローチャートに基づく制御で実行することができる。
【００４２】
ここで、上記の具体例とこの発明との関係を簡単に説明すると、図１に示すステップＳ３の機能的手段が、請求項２のフィルタ処理手段に相当し、そのステップＳ３における相関係数ｋ（ｉ） を変速比勾配Δγに置き換えたステップＳ３の機能的手段が、請求項１のフィルタ処理手段に相当する。同様に、ステップＳ４，Ｓ６の機能的手段が、請求項２の滑り判定手段に相当し、その相関係数ｋ（ｉ） のハイパスフィルタ処理値ｋ＿ｈｉ（ｉ）を変速比勾配Δγのハイパスフィルタ処理値Δγ＿ｈｉ（ｉ）に置き換えたステップＳ４，Ｓ６の機能的手段が、請求項１の滑り判定手段に相当する。そして、ステップＳ７の機能的手段が、請求項３の制御手段に相当する。
【００４３】
なお、この発明は上記の具体例に限定されないのであって、ベルト式無段変速機以外にトラクション式の無段変速機を対象とする制御装置にも適用することができる。また、上記の各しきい値は、予め定めた一定値であってもよいが、車両の加減速度やスロットル開度などの運転状態に基づいて変化する変数（マップ値）であってもよい。さらに、この発明のフィルタ処理は、要は、滑り判定に対して外乱となる信号成分を除去できるものであればよいから、ハイパスフィルタ処理に限らず所定の周波数帯域の成分のみを出力するバンドパイフィルタ処理であってもよい。
【００４４】
【発明の効果】
以上説明したように、請求項１の発明によれば、変速比の変化速度が検出されるとともに、その検出信号がフィルタ処理され、そのフィルタ処理値が所定のしきい値と比較されるなどのことによって無段変速部での滑りが判定されるため、滑りに起因しない信号を除去した状態で滑りを判定でき、その結果、滑り判定精度が向上し、また小さい滑りであっても精度良く検出することが可能になる。
【００４５】
また、請求項２の発明によれば、入出力回転数に基づいて相関係数が求められるとともにその相関係数の検出信号がフィルタ処理され、そのフィルタ処理値が所定のしきい値と比較されるなどのことによって無段変速部での滑りが判定されるため、滑りに起因しない信号を除去した状態で滑りを判定でき、その結果、滑り判定精度が向上し、また小さい滑りであっても精度良く検出することが可能になる。
【００４６】
さらに、請求項３の発明によれば、無段変速部での滑りが検出されると、所定の制御が実行されるので、その滑りを抑制もしくは解消することができる。
【図面の簡単な説明】
【図１】この発明の制御装置による制御の一例を説明するためのフローチャートである。
【図２】図１に示すフローチャートに対応するタイムチャートの一例である。
【図３】滑りが生じた場合および変速が開始された場合の変速比、変速比勾配、そのハイパスフィルタ処理値の変化を模式的に示す図である。
【図４】この発明で対象とする無段変速機を含む駆動系統の一例を模式的に示す図である。
【符号の説明】
１…無段変速機、 ４…エンジン（動力源）、 １９…駆動プーリ、 ２０…従動プーリ、 ２３…ベルト、 ２９…入力軸回転速度センサー、 ３０…出力軸回転速度センサー、 ３１…変速機用電子制御装置（ＣＶＴ−ＥＣＵ）。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention detects slippage of a continuously variable transmission (more specifically, slippage at a continuously variable transmission portion) using a speed ratio, a change speed, a correlation coefficient, and the like, and determines a predetermined value based on the detection result. The present invention relates to a control device that executes the control of (1).
[0002]
[Prior art]
Conventionally, a belt type continuously variable transmission and a toroidal type continuously variable transmission are known. In these continuously variable transmissions, torque is transmitted using the frictional force between the belt and the pulley and the shearing force of the traction oil sandwiched between the disk and the roller, so that the transmittable torque is limited. When a torque exceeding the torque capacity acts, excessive slippage may occur. If such a slip occurs, the continuously variable transmission may be damaged. Therefore, when the slip occurs or when the vehicle reaches a state immediately before the slip occurs, the torque capacity is increased. Alternatively, it is desired to reduce the torque acting on the continuously variable transmission.
[0003]
Therefore, in controlling the continuously variable transmission, it is necessary to detect the slip or the state immediately before the slip, and various devices and methods have been proposed. For example, Patent Document 1 discloses an apparatus that detects belt slippage based on a change speed of a gear ratio exceeding a reference value. The failure diagnosis device for a continuously variable transmission described in Patent Document 1 has a rotation sensor that detects the number of rotations of a main pulley and a sub-pulley, and the control unit changes the speed based on a signal from the rotation sensor. The ratio is calculated, a failure is determined from at least one of the value of the speed ratio and the value of the speed ratio change speed, and an alarm is issued based on the number of times of the failure determination.
[0004]
Patent Document 2 discloses a device for detecting slippage in a wrapping transmission device, in which a detection signal of an acceleration sensor or a sound pressure sensor is band-pass filtered to extract a vibration component in a specific low frequency band. Describes a device configured to determine slippage based on its vibration level. Further, Patent Literature 3 discloses an apparatus configured to obtain a virtual speed ratio by performing a first-order lag filter process on an actual speed ratio and determine slippage based on a comparison result between the virtual speed ratio and the actual speed ratio. ing. Patent Literature 4 discloses an apparatus configured to process a detection signal of a winding radius by a low-pass filter and obtain an actual slip value using the processed value.
[0005]
[Patent Document 1]
JP-B-62-2059 (Claims)
[Patent Document 2]
JP 2001-108082 A (paragraphs (0058) and (0059))
[Patent Document 3]
JP 2001-349418 A (Claims 2 to 5)
[Patent Document 4]
Japanese Patent Publication No. Hei 8-511330 (pp. 10-11, FIG. 5)
[0006]
[Problems to be solved by the invention]
The change factors of the speed ratio in the continuously variable transmission are various, and are not limited to acceleration requests and deceleration requests, and the speed ratio also changes when the input rotation speed or the output rotation speed changes for some reason. The speed ratio change speed is not only the speed at the time of the so-called normal speed change based on the acceleration / deceleration request, but also becomes the speed change speed at the time of the sudden speed change caused by the so-called disturbance.
[0007]
Therefore, in order to distinguish the speed ratio change speeds which are variously different from the speed ratio change speeds caused by the slip, a threshold value exceeding the speed ratio change speed which is considered to be generated during running is set, When a speed ratio change speed exceeding the above is detected, the occurrence of slip is determined based on this. Therefore, as described in Patent Document 1 described above, in a case where slippage is determined when the speed ratio change speed exceeds a predetermined reference value, in order to prevent erroneous slippage determination. Since the reference value has to be increased, there is a possibility that a slip in which the speed ratio changes relatively slowly or a so-called relatively small slip cannot be detected. In other words, the slip detection accuracy is not always high, and there is room for improvement in that respect.
[0008]
The present invention has been made in view of the above technical problem, and has as its object to provide a control device for a continuously variable transmission that can accurately detect slippage including so-called small slippage. It is.
[0009]
Means for Solving the Problems and Their Functions
The present invention is characterized in that, in order to achieve the above object, slip is determined by extracting a component based on slip from a predetermined detection signal that can be obtained from the input / output rotation speed. is there. That is, the invention of claim 1 is a control device for a continuously variable transmission that detects slippage in a continuously variable transmission portion based on a speed ratio change speed, wherein a filter processing means for filtering a speed ratio change speed detection signal; And a slip detecting means for judging a slip in the continuously variable transmission section based on a filter processing value processed by the filter processing means.
[0010]
Therefore, according to the first aspect of the present invention, the speed of change of the gear ratio is detected, the detection signal is filtered, and the filtered value is compared with a predetermined threshold value. Is determined. Therefore, slip is determined in a state in which a signal not caused by slip is removed, and the determination accuracy is improved.
[0011]
The invention according to claim 2 is a control device for a continuously variable transmission that detects slippage of a continuously variable transmission portion based on a correlation coefficient between an input rotation speed and an output rotation speed of the continuously variable transmission. Filter processing means for filtering the number of detection signals, and slip detection means for determining slip in the continuously variable transmission portion based on the filtered value processed by the filter processing means. It is a control device to perform.
[0012]
Therefore, according to the second aspect of the present invention, the correlation coefficient is obtained based on the input / output rotation speed, the detection signal of the correlation coefficient is filtered, and the filtered value is compared with a predetermined threshold value. Thus, slippage in the continuously variable transmission is determined. Therefore, slip is determined in a state in which a signal not caused by slip is removed, and the determination accuracy is improved.
[0013]
Further, the invention according to claim 3 further comprises, in addition to the configuration according to claim 1 or 2, further comprising control means for controlling the continuously variable transmission based on detection of slippage in the continuously variable transmission portion. A control device characterized in that:
[0014]
Therefore, in the invention of claim 3, when slippage in the continuously variable transmission is detected, predetermined control is executed to suppress or eliminate the slippage.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described based on specific examples. First, a drive mechanism including a continuously variable transmission according to the present invention will be described. The present invention can be applied to a continuously variable transmission mounted on a vehicle, and the continuously variable transmission includes a belt. A belt-type continuously variable transmission that uses a torque transmission member, or a toroidal (traction-type) continuously variable transmission that uses a power roller as a torque transmission member and transmits torque using the shear force of oil (traction oil). is there. FIG. 4 schematically shows an example of a vehicle drive mechanism including a belt-type continuously variable transmission 1. The continuously variable transmission 1 is driven by a forward / reverse switching mechanism 2 and a torque converter 3. It is connected to a source 4.
[0016]
The power source 4 is similar to a power source mounted on a general vehicle, and is an internal combustion engine such as a gasoline engine, a diesel engine or a natural gas engine, an electric motor, or a combination of an internal combustion engine and an electric motor. A mechanism or the like can be adopted. In the following description, the power source 4 is referred to as an engine 4.
[0017]
The torque converter 3 connected to the output shaft of the engine 4 has the same structure as the torque converter used in the conventional general vehicle, and the pump impeller 6 is attached to the front cover 5 connected to the output shaft of the engine 4. A turbine runner 7 that is integrated and faces the pump impeller 6 is disposed adjacent to the inner surface of the front cover 5. The pump impeller 6 and the turbine runner 7 are provided with a large number of blades (not shown). The rotation of the pump impeller 6 generates a spiral flow of fluid, and the spiral flow is generated by the turbine runner 7. , A torque is given to the turbine runner 7 to rotate it.
[0018]
A stator 8 that selectively changes the flow direction of the fluid sent out from the turbine runner 7 and flows into the pump impeller 6 is disposed in an inner peripheral portion between the pump impeller 6 and the turbine runner 7. . The stator 8 is connected to a predetermined fixed part 10 via a one-way clutch 9.
[0019]
This torque converter 3 includes a lock-up clutch 11. The lock-up clutch 11 is disposed in parallel with a substantial torque converter including a pump impeller 6, a turbine runner 7, and a stator 8. The lock-up clutch 11 faces the inner surface of the front cover 5 and , And is pressed against the inner surface of the front cover 5 by hydraulic pressure, whereby torque is directly transmitted from the front cover 5 as an input member to the turbine runner 7 as an output member. The torque capacity of the lock-up clutch 11 can be controlled by controlling the oil pressure.
[0020]
The forward / reverse switching mechanism 2 is a mechanism that is employed in accordance with the fact that the rotation direction of the engine 4 is limited to one direction. The forward / reverse switching mechanism 2 outputs the input torque as it is and outputs it in reverse. It is configured. In the example shown in FIG. 4, a double pinion type planetary gear mechanism is employed as the forward / reverse switching mechanism 2.
[0021]
That is, the ring gear 13 is arranged concentrically with the sun gear 12, and a pinion gear 14 meshed with the sun gear 12 and another pinion gear 15 meshed with the pinion gear 14 and the ring gear 13 are arranged between the sun gear 12 and the ring gear 13. The pinion gears 14 and 15 are held by the carrier 16 so as to rotate and revolve. A forward clutch 17 for integrally connecting the two rotating elements (specifically, the sun gear 12 and the carrier 16) is provided, and by selectively fixing the ring gear 13, the direction of the output torque is provided. Is provided with a reverse brake 18 for reversing.
[0022]
The continuously variable transmission 1 has the same configuration as a conventionally known belt-type continuously variable transmission, and each of a drive pulley 19 and a driven pulley 20 disposed in parallel with each other includes a fixed sheave and a hydraulic pulley. A movable sheave that is moved back and forth in the axial direction by actuators 21 and 22. Accordingly, the groove width of each pulley 19, 20 changes by moving the movable sheave in the axial direction, and accordingly, the winding radius of the belt 23 wound around each pulley 19, 20 (the effective diameter of the pulleys 19, 20). ) Changes continuously, and the gear ratio changes steplessly. The drive pulley 19 is connected to the carrier 16 which is an output element of the forward / reverse switching mechanism 2. These pulleys 19, 20 and belt 23 constitute a continuously variable transmission.
[0023]
The hydraulic actuator 22 in the driven pulley 20 is supplied with a hydraulic pressure (line pressure or its correction pressure) according to the torque input to the continuously variable transmission 1 via a hydraulic pump and a hydraulic control device (not shown). I have. Therefore, when each sheave of the driven pulley 20 sandwiches the belt 23, tension is applied to the belt 23, and a clamping pressure (contact pressure) between each of the pulleys 19 and 20 and the belt 15 is secured. . In other words, the torque capacity according to the clamping pressure is set. On the other hand, the hydraulic oil in the drive pulley 19 according to the gear ratio to be set is supplied to the hydraulic actuator 21, and the groove width (effective diameter) according to the target gear ratio is set. .
[0024]
A driven pulley 20, which is an output member of the continuously variable transmission 1, is connected to a gear pair 24 and a differential 25, and the differential 25 is connected to left and right drive wheels 26.
[0025]
Various sensors are provided to detect the operation state (running state) of the vehicle equipped with the above-described continuously variable transmission 1 and the engine 4. That is, an engine rotation speed sensor 27 that detects the output shaft rotation speed of the engine 4 (the input shaft rotation speed of the lock-up clutch 11) Ne and outputs a signal, and a turbine that detects the rotation speed of the turbine runner 7 and outputs a signal. A rotation speed sensor 28, an input shaft rotation speed sensor 29 that detects a rotation speed Nin of the driving pulley 19 and outputs a signal, an output shaft rotation speed sensor 30 that detects a rotation speed Nout of the driven pulley 20 and outputs a signal, and the like. Is provided.
[0026]
Control of the engagement and release of the forward clutch 17 and the reverse brake 18, control of the clamping force of the belt 23, control of the torque capacity including engagement and release of the lock-up clutch 11, and further, the gear ratio A transmission electronic control unit (CVT-ECU) 31 is provided in order to perform the above control. The electronic control unit 31 is configured mainly by a microcomputer as an example, performs calculations according to a predetermined program based on input data and data stored in advance, and various states such as forward, reverse, and neutral, It is configured to execute control such as setting of a required squeezing pressure and setting of a gear ratio. Further, an engine electronic control unit (E-ECU) 32 for controlling the engine 4 is provided, and these electronic control units 31 and 32 mutually communicate data.
[0027]
The control device of the present invention for the above-described continuously variable transmission 1 is configured such that any one of the belt 23 and any one of the belts 23 is It is configured to detect slippage between the pulleys 19 and 20, that is, slippage in the continuously variable transmission. FIG. 1 shows an example of the control, and the routine shown in the flowchart of FIG. 1 is repeatedly executed at predetermined short time intervals t.
[0028]
In FIG. 1, first, an input shaft rotation speed (input rotation speed) Nin (i) and an output shaft rotation speed (output rotation speed) Nout (i) of the continuously variable transmission 1 are measured (step S1). Then, the correlation coefficient k (i) is calculated using the latest N input shaft rotation speeds Nin and output shaft rotation speeds Nout (Step S2). The correlation coefficient k (i) can be represented by a general formula as follows, and details thereof are described in, for example, the specification attached to Japanese Patent Application No. 2001-302181.
(Equation 1)

[0029]
The correlation coefficient k (i) is “1” if the mutual relationship (for example, the gear ratio γ) between the input shaft rotation speed Nin (i) and the output shaft rotation speed Nout (i) is constant and does not change. When the mutual relationship (for example, the gear ratio γ) between the two rotational speeds changes due to the decrease or increase in one of the rotational speeds, the value becomes smaller than “1” in the process.
[0030]
The input shaft rotation speed Nin (i) and the output shaft rotation speed Nout (i) of the continuously variable transmission 1 (in particular, the input shaft rotation speed Nin (i)) change when the belt 23 slips, and , The mutual relationship between the rotational speeds Nin (i) and Nout (i) also changes when the gear ratio γ is changed. Since the mode of change caused by the slip is different from the mode of change of the rotational speed when the gear ratio γ is changed, it is distinguished by which the change of the correlation coefficient k (i) is caused. Therefore, the detection signal of the correlation coefficient k (i) is filtered (step S3). This filter processing is, for example, a high-pass filter processing, and the processing value k_hi (i) is calculated.
[0031]
FIG. 2 shows the rotational speeds Nin (i) and Nout (i), the gear ratio γ, the correlation coefficient k (i), and the high-pie filter processing value k_hi when slippage and upshifting occur sequentially during acceleration. The change of (i) is schematically shown. As known from FIG. 2, when the slip occurs, each of the rotational speeds Nin (i) and Nout (i) instantaneously changes, and the gear ratio γ changes accordingly. In the example of FIG. 2, the speed ratio γ changes toward the downshift side.
[0032]
Therefore, the correlation coefficient k (i) obtained from each of the rotation speeds Nin (i) and Nout (i) and the high-pass filter processing value k_hi (i) are instantaneously greatly reduced. On the other hand, when an upshift occurs, the input shaft rotation speed Nin (i) decreases to some extent, and accordingly, the correlation coefficient k (i) decreases. The speed of the change corresponds to the speed of change of the speed ratio γ, and is considerably slower than in the case of a change caused by slippage. Therefore, although the processing value k_hi (i) obtained by performing the high-pass filter processing for cutting the low frequency range changes, the reduction value is small.
[0033]
Therefore, in step S4 following step S3, it is determined whether or not the high-pass filter processing value k_hi (i) is smaller than a predetermined threshold value kslp. This threshold value kslp is also shown in FIG. 2. The value of the threshold value kslp is a value at which the correlation coefficient k (i) at the time of shifting reaches, but the high-pass filter processing value k_hi (i) does not.
[0034]
When a negative determination is made in step S4, the slip determination is not established, and normal control is executed (step S5). This normal control is, for example, a control for reducing the belt clamping pressure during steady running or quasi-steady running on a flat road, and running on a rough road, or an unsteady running such as a large acceleration / deceleration. In the case of traveling, the control is to increase the clamping pressure to approximately the line pressure.
[0035]
On the other hand, if a positive determination is made in step S4, a determination of belt slip is made (step S6). Then, the control corresponding thereto is executed (step S7). The corresponding control in step S7 is, in short, control for relatively increasing the transmission torque capacity with respect to the torque acting on the continuously variable transmission 1, for example, control for increasing the belt clamping pressure. Alternatively, or at the same time, control for reducing the engine torque may be executed.
[0036]
Therefore, according to the control by the apparatus according to the present invention described above, although slippage in the continuously variable transmission is detected using the correlation coefficient k (i), the slippage is included in the detection signal of the correlation coefficient k (i). The change component accompanying the normal shift is removed by the high-pass filter processing, and the slip is determined based on the high-pass filter processing value k_hi (i). Therefore, accurate slip determination or detection can be performed. Further, even if the correlation coefficient k (i) associated with a normal shift becomes a small value, the high-pass filter processing value k_hi (i) does not decrease significantly. The value can be set to a relatively large value slightly smaller than "1", and as a result, even a so-called small slip that the filtering value of the correlation coefficient k (i) slightly decreases is detected. This also increases the slip detection accuracy.
[0037]
Since the input shaft rotation speed Nin (i) and the output shaft rotation speed Nout (i) change regardless of whether belt slippage or shifting occurs, the above-described correlation coefficient k (i) In addition, the gear ratio γ and its change gradient Δγ change. Since the manners of these changes are different between the case due to slippage and the case due to shift control, any one of the detection signals is filtered in the same manner as in the above-described specific example, whereby A distinction can be made between changes due to shifting and changes due to shifting. FIG. 3 schematically shows an example using the speed ratio gradient Δγ.
[0038]
FIG. 3 shows changes in the speed ratio γ, the speed ratio gradient Δγ, and the high-pass filter processing value Δγ_hi (i) when a belt slip occurs and when a shift is started. For example, if the belt slips during acceleration, the gear ratio γ temporarily increases to the downshift side. Accordingly, the speed ratio gradient Δγ changes so as to pulsate to a large or small value. In this case, since no shift has occurred, there is almost no change in the speed ratio γ over a relatively long time width, and thus the detected speed ratio gradient Δγ changes at a relatively high frequency. Therefore, there is no component that is particularly removed even when the speed ratio gradient Δγ is subjected to the high-pass filter processing, and the high-pass filter processing value Δγ_hi (i) shows a change similar to the speed ratio gradient Δγ.
[0039]
On the other hand, when the gear ratio γ is increased, for example, to the downshift side by the gear shift control, the gear shift is performed to some extent slowly in order to prevent gear shift shock and loss of power, so that the gear ratio gradient Δγ is small and the change amount Is also smaller. Then, when high-pass filter processing for removing low-frequency components from the detection signal of the speed ratio gradient Δγ is performed, the filter processing value Δγ_hi (i) becomes a small value.
[0040]
Therefore, by setting a small value that is slightly higher than the filter processing value at the time of shifting as the belt slip determination threshold Δγslp based on the high-pass filter processing value Δγ_hi (i) of the speed ratio gradient Δγ, A shift can be distinguished. In other words, the detection accuracy of the belt slip is improved, and the smaller slip can be accurately detected because the threshold value can be reduced.
[0041]
The determination of the belt slip using the speed ratio gradient Δγ and the filter processing value Δγ_hi (i) is performed by, for example, the correlation coefficient k (i) and the high-pass filter processing value k_hi (i) in the flowchart shown in FIG. The threshold kslp can be executed by the control based on the flowchart in which the speed ratio gradient Δγ and the high-pass filter processing value Δγ_hi (i) are replaced with the threshold Δγslp, respectively.
[0042]
Here, the relationship between the above specific example and the present invention will be briefly described. The functional means in step S3 shown in FIG. 1 corresponds to the filter processing means in claim 2, and the correlation coefficient k in step S3 The functional means of step S3 in which (i) is replaced by the speed ratio gradient Δγ corresponds to the filter processing means of claim 1. Similarly, the functional means of steps S4 and S6 correspond to the slip determination means of claim 2, and the high-pass filter processing value k_hi (i) of the correlation coefficient k (i) is subjected to high-pass filter processing of the speed ratio gradient Δγ. The functional means of steps S4 and S6 replaced with the value Δγ_hi (i) correspond to the slip determination means of claim 1. Then, the functional means of step S7 corresponds to the control means of claim 3.
[0043]
The present invention is not limited to the above specific example, and can be applied to a control device for a traction type continuously variable transmission other than the belt type continuously variable transmission. Further, each of the above threshold values may be a predetermined constant value, or may be a variable (map value) that changes based on the driving state such as the acceleration / deceleration of the vehicle and the throttle opening. Further, the filter processing of the present invention is not limited to the high-pass filter processing, but may be a band pie that outputs only a component of a predetermined frequency band, as long as it can remove a signal component that disturbs the slip determination. Filter processing may be used.
[0044]
【The invention's effect】
As described above, according to the first aspect of the invention, the speed of change of the gear ratio is detected, the detection signal is filtered, and the filtered value is compared with a predetermined threshold value. As a result, slippage in the continuously variable transmission is determined, so that slippage can be determined with signals that are not caused by slippage removed.As a result, slippage determination accuracy is improved, and even small slippages are accurately detected. It becomes possible to do.
[0045]
According to the second aspect of the present invention, a correlation coefficient is obtained based on the input / output rotation speed, a detection signal of the correlation coefficient is filtered, and the filtered value is compared with a predetermined threshold value. For example, the slip in the continuously variable transmission portion is determined by the following, so that the slip can be determined in a state in which a signal not caused by the slip is removed.As a result, the slip determination accuracy is improved, and even if the slip is small, It is possible to detect with high accuracy.
[0046]
Further, according to the third aspect of the present invention, when slippage in the continuously variable transmission is detected, predetermined control is executed, so that the slippage can be suppressed or eliminated.
[Brief description of the drawings]
FIG. 1 is a flowchart illustrating an example of control by a control device according to the present invention.
FIG. 2 is an example of a time chart corresponding to the flowchart shown in FIG. 1;
FIG. 3 is a diagram schematically illustrating a change in a gear ratio, a gear ratio gradient, and a high-pass filter processing value thereof when a slip occurs and a shift is started.
FIG. 4 is a diagram schematically illustrating an example of a drive system including a continuously variable transmission according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Continuously variable transmission, 4 ... Engine (power source), 19 ... Drive pulley, 20 ... Followed pulley, 23 ... Belt, 29 ... Input shaft rotation speed sensor, 30 ... Output shaft rotation speed sensor, 31 ... For transmission Electronic control unit (CVT-ECU).

Claims (3)

In the control device of the continuously variable transmission that detects slippage in the continuously variable transmission portion based on the speed ratio change speed,
Filtering means for filtering the detection signal of the speed ratio change speed;
A control device for a continuously variable transmission, comprising: a slip detection unit that determines a slip in the continuously variable transmission unit based on a filter processing value processed by the filter processing unit. A control device for a continuously variable transmission that detects slippage of a continuously variable transmission unit based on a correlation coefficient between an input rotation speed and an output rotation speed for a continuously variable transmission,
Filter processing means for filtering the detection signal of the correlation coefficient,
A control device for a continuously variable transmission, comprising: a slip detection unit that determines a slip in the continuously variable transmission unit based on a filter processing value processed by the filter processing unit. The control of the continuously variable transmission according to claim 1 or 2, further comprising control means for controlling the continuously variable transmission based on detection of slippage in the continuously variable transmission unit. apparatus.

Images