JP5936633B2 - Shift control device for belt type continuously variable transmission - Google Patents

Description

  The present invention relates to a transmission control device for a belt-type continuously variable transmission that can change a transmission gear ratio when a power between pulleys is transmitted by a belt continuously.

  Conventionally, in Patent Document 1, in a belt-type continuously variable transmission, when a vehicle moves in a direction opposite to the currently selected travel range when the vehicle restarts after temporarily stopping on an uphill road or the like, the torque of the pulley In order to solve the problem of belt slippage due to a change in capacity, a technique for suppressing belt slippage by increasing the line pressure and correcting the torque capacity when reverse rotation of the pulley is detected is disclosed. .

JP 2007-263151 A

However, as a result of intensive studies by the inventor, even if the line pressure is increased when reverse rotation occurs, the gear ratio shifts to the high side, and the desired gear ratio cannot be obtained and the startability is improved. A new problem has been found that will lead to deterioration.
The present invention has been made paying attention to the above problems, and provides a shift control device for a belt-type continuously variable transmission that can achieve stable shift control even when reverse rotation occurs in a pulley. Objective.

In order to achieve the above object, the shift control device for a belt-type continuously variable transmission according to the present invention calculates a thrust ratio based on an input torque to the belt-type continuously variable transmission and a target gear ratio, and calculates the thrust ratio. The reference pulley hydraulic pressure is calculated, the feedback hydraulic pressure is calculated by feedback control according to the difference between the target gear ratio and the actual gear ratio, and the shift control is performed based on the reference pulley hydraulic pressure and the feedback hydraulic pressure. At this time, when the vehicle speed is less than a predetermined value where the accuracy cannot be sufficiently secured due to the detection resolution of the vehicle speed sensor , the feedback control is stopped and the thrust ratio is the lowest gear ratio and the input torque Regardless, the lowest speed gear ratio can be achieved, and the speed change control is performed by setting a predetermined thrust ratio lower than the thrust ratio set when the input torque is zero.

  Therefore, it becomes possible to control based on a low thrust ratio, and stable shift control can be achieved by suppressing the shift to the high side.

1 is a system diagram illustrating a shift control device for a belt-type continuously variable transmission according to a first embodiment. FIG. 3 is a control block diagram illustrating a shift control process according to the first embodiment. 3 is a map showing characteristics of a secondary hydraulic pressure with respect to a required torque in the first embodiment. 3 is a torque ratio-thrust ratio map used for shift control of the belt-type continuously variable transmission according to the first embodiment.

  FIG. 1 is a system diagram illustrating a shift control device for a belt-type continuously variable transmission according to a first embodiment. The vehicle according to the first embodiment includes an engine 1 that is an internal combustion engine and a belt-type continuously variable transmission, and transmits driving force to driving wheels 8 through a differential gear 7. The belt type continuously variable transmission includes a transmission input shaft 2 connected to the crankshaft of the engine 1, a primary pulley 3 that rotates integrally with the transmission input shaft 2, and a secondary that rotates integrally with the transmission output shaft 6. A pulley 5 and a belt 4 wound between the primary pulley 3 and the secondary pulley 5 to transmit power are included.

  The primary pulley 3 has a fixed sheave 3a formed integrally with the transmission input shaft 2 and a movable sheave 3b movable on the transmission input shaft 2. The movable sheave 3b is provided with a primary hydraulic chamber 3b1, and a pressing force is generated between the fixed sheave 3a and the movable sheave 3b by the hydraulic pressure supplied to the primary hydraulic chamber 3b1, thereby pinching the belt 4. Similarly, the secondary pulley 5 includes a fixed sheave 5a formed integrally with the transmission output shaft 6 and a movable sheave 5b movable on the transmission output shaft 6. The movable sheave 5b is provided with a secondary hydraulic chamber 5b1, and a pressing force is generated between the fixed sheave 5a and the movable sheave 5b by the hydraulic pressure supplied to the secondary hydraulic chamber 5b1, thereby sandwiching the belt 4.

The engine controller 10 controls the engine speed and the engine torque by controlling the operating state (fuel injection amount, ignition timing, etc.) of the engine 1. Further, in the engine controller 10, a required torque calculation unit that calculates the driver's required torque TD based on the accelerator opening signal APO detected by the accelerator opening sensor 21 and the vehicle speed signal VSP detected by the vehicle speed sensor 22. 10a and an engine torque calculation unit 10b for calculating the engine torque TENG transmitted to the transmission input shaft 2.
In the transmission controller 20, the primary hydraulic pressure and the secondary hydraulic pressure corresponding to the traveling state are calculated and a control signal is output to the control valve unit 30. Details of the transmission controller 20 will be described later.
The control valve unit 30 uses the oil pump 9 chain-driven to the transmission input shaft 2 as a hydraulic pressure source, and adjusts each hydraulic pressure based on a control signal transmitted from the transmission controller 20. Then, the primary hydraulic pressure and the secondary hydraulic pressure are respectively supplied to the primary hydraulic chamber 3b1 and the secondary hydraulic chamber 5b1, and the shift control is executed.

  FIG. 2 is a control block diagram showing a shift control process in the transmission controller of the first embodiment. The target gear ratio calculation unit 201 calculates the target gear ratio Ga based on the accelerator opening signal APO and the vehicle speed signal VSP. This target speed ratio Ga is performed based on a speed change characteristic set in advance so that the engine 1 achieves the optimum fuel consumption. The torque ratio calculation unit 202 calculates a torque ratio Qt that is a ratio of the engine torque TENG to the torque Tmax (see FIG. 3) corresponding to the secondary hydraulic pressure set based on the required torque TD.

  The actual speed ratio calculation unit 203 reads the primary speed Npri detected by the primary speed sensor 23 and the secondary speed Nsec detected by the secondary speed sensor 24, and calculates the actual speed ratio Gb. The primary and secondary rotational speed sensors 23 and 24 are rotational speed sensors that detect the unevenness during rotation of a rotating body with unevenness on the outer periphery by changing the magnetic field of the coil, and detect the rotational speed at low cost. Although it is possible, the direction of rotation cannot be recognized. Further, since the resolution is determined by the width of the unevenness, it is difficult to detect the correct rotational speed in the extremely low vehicle speed region.

  The deviation calculating unit 204 calculates a deviation ΔG between the target speed ratio Ga and the actual speed ratio Gb. The feedback calculation unit 205 calculates the feedback hydraulic pressure based on the detected deviation ΔG. For example, a hydraulic pressure (hereinafter referred to as feedback hydraulic pressure) to be added to or subtracted from the primary hydraulic pressure and / or the secondary hydraulic pressure by PI control or PID control is output.

  The first thrust calculation unit 206 calculates the pulley thrust ratio from a preset map based on the target gear ratio Ga and the torque ratio Qt calculated by the torque ratio calculation unit 202. FIG. 4 is a torque ratio-thrust ratio map used for shift control of the belt type continuously variable transmission according to the first embodiment. A characteristic is selected based on the target gear ratio Ga, and a thrust ratio Qf is calculated from the selected characteristic and the torque ratio Qt. Next, a reference secondary oil pressure Psec, which is a reference oil pressure, is calculated based on the required torque TD from the map representing the secondary oil pressure characteristics in FIG. 3, and the reference secondary oil pressure Ppri is multiplied by the thrust ratio Qf. Is calculated. Hereinafter, the reference secondary oil pressure Psec and the reference primary oil pressure Ppri are collectively referred to as a reference pulley oil pressure.

The multiplication unit 207 adds the feedback hydraulic pressure to the reference pulley hydraulic pressure, and describes a first primary hydraulic pressure command value and a first secondary hydraulic pressure command value (hereinafter collectively referred to as a first pulley hydraulic pressure command value) used during normal shift control. .) Is output.
The second thrust calculation unit 208 determines a second secondary hydraulic pressure command value based on the required torque TD, and based on a preset low vehicle speed thrust ratio Qf0, the second primary hydraulic pressure command value (hereinafter collectively referred to as the first 2) Describe the pulley oil pressure command value.

  Based on the vehicle speed VSP, the control switching unit 209 determines whether or not the vehicle speed VSP1 is less than the vehicle speed VSP1 where the accuracy cannot be sufficiently secured from the relationship of the detection resolution of the vehicle speed sensor 22, and if it is less than VSP1, switches to the second pulley hydraulic pressure command value. If VSP1 or higher, switch to the first pulley oil pressure command value. In other words, when the vehicle speed is VSP1 or higher, the speed change control is performed to achieve the desired speed ratio by feedback control, and when it is less than VSP1, the feedback control is prohibited, and the lowest speed shift based on the low vehicle speed thrust ratio Qf0. To achieve the ratio.

  Here, the reason why the control switching unit 209 is provided will be described. Normally, the thrust ratio Qf is calculated from the torque ratio Qt based on the map shown in FIG. 4, and the first pulley hydraulic pressure command value is calculated based on the thrust ratio Qf. However, in the low vehicle speed region including the vehicle stop state, the detection accuracy of the primary rotational speed sensor 23 and the secondary rotational speed sensor 24 cannot be ensured, and compensation by feedback control cannot be performed sufficiently. Further, when the vehicle restarts from a vehicle stop on an uphill road or the like, for example, even if the driver selects the D range and intends to move forward, there may be a scene of sliding backward depending on the slope. At this time, since the primary pulley 3 also turns to the opposite side to the forward side, the input torque Tin becomes a negative value. At this time, as shown in the map of FIG. 4, when the torque ratio Qt is a negative predetermined value (-Qt1: a state where the primary rotational speed is reversely rotated), the thrust ratio to be set has a characteristic to be reduced. .

However, since the primary rotation speed sensor 23 and the secondary rotation speed sensor 24 cannot recognize the rotation direction, it is impossible to determine whether the rotation is reverse, and the torque ratio Qt is a predetermined positive value (Qt1: primary rotation speed is normal rotation). May be misrecognized and controlled. Then, since the actual torque ratio is -Qt, the gear ratio commensurate with this torque ratio Qt is G3 in FIG. 4 (the gear ratio higher than G1), and the belt type continuously variable transmission is the lowest. Upshift from gear ratio to high side. Then, even if torque is output from the engine 1 side, a sufficient reduction ratio cannot be obtained, and there is a problem that startability deteriorates.
Therefore, in the first embodiment, when the vehicle speed is lower than the predetermined vehicle speed VSP1, the feedback control is prohibited, and the predetermined speed lower than the thrust ratio Qf1 set when the torque ratio Qt is zero and the lowest gear ratio is set. The thrust ratio is set to Qf0. As a result, the lowest speed ratio can be ensured regardless of the value of the torque ratio Qt, and stable shift control can be achieved.

As described above, the effects listed below are obtained in the first embodiment.
(1) A belt-type continuously variable transmission including a primary pulley 3, a secondary pulley 5, and a belt 4 wound around both pulleys, and an engine torque TENG (input torque to the belt-type continuously variable transmission) Based on the target gear ratio Ga, a thrust ratio, which is a ratio of pulley hydraulic pressure supplied to the hydraulic chamber of each pulley, is calculated, a reference pulley hydraulic pressure is calculated based on the thrust ratio, and the target gear ratio Ga and the actual gear ratio Gb are calculated. Of a belt-type continuously variable transmission including a transmission controller 20 (transmission control means) that calculates a feedback hydraulic pressure by feedback control according to a difference between the reference pulley hydraulic pressure and the reference pulley hydraulic pressure and the feedback hydraulic pressure. In the speed change control device, the transmission controller 20 stops the feedback control when the predetermined operating condition is satisfied, and the thrust ratio is the lowest speed ratio and the torque ratio Qt ( The shift control is performed by setting a low vehicle speed thrust ratio Qf0 (predetermined thrust ratio) lower than the thrust ratio Qf1 set when the input torque) is zero.
Therefore, it is possible to perform shift control based on a low thrust ratio, and stable shift control can be achieved by suppressing the shift to the high side.

(2) The low vehicle speed thrust ratio Qf0 is a thrust ratio that can achieve the lowest gear ratio regardless of the torque ratio Qt. Therefore, the lowest speed ratio can always be ensured regardless of the input torque.
(3) The predetermined driving condition is that the vehicle speed is less than the predetermined vehicle speed VSP1. Therefore, in a region where the resolution of the rotational speed sensor is reduced, such as a low vehicle speed region, stable shift control can be realized by performing control based on a fixed thrust ratio without performing feedback control.

(Other examples)
As described above, the description is based on the first embodiment. However, the present invention is not limited to the above-described embodiment, and other configurations are also included in the present invention. In the first embodiment, the predetermined thrust ratio Qf0 is set as a fixed value. However, for example, the thrust ratio corresponding to the torque ratio Qt may be variably set within a range smaller than Qf1. Further, although the control switching unit 209 is operated based on whether the vehicle speed VSP is less than the predetermined vehicle speed VSP1 as a predetermined driving condition, the control switching may be performed according to the torque ratio without being limited to the vehicle speed.

1 engine
2 Transmission input shaft
3 Primary pulley
3a Fixed sheave
3b Movable sheave
3b1 Primary hydraulic chamber
4 belt
5 Secondary pulley
5a Fixed sheave
5b Movable sheave
5b1 Secondary hydraulic chamber
10 Engine controller
10a Required torque calculator
10b Actual engine torque calculator
20 Transmission controller
30 Control valve unit
201 Target gear ratio calculator

Claims (1)

A belt-type continuously variable transmission comprising a primary pulley, a secondary pulley, and a belt wound around both pulleys;
A vehicle speed sensor for detecting the vehicle speed;
Based on the input torque to the belt type continuously variable transmission and the target gear ratio, a thrust ratio that is a ratio of pulley hydraulic pressure supplied to the hydraulic chamber of each pulley is calculated, and a reference pulley hydraulic pressure is calculated based on the thrust ratio And a shift control means for calculating a feedback hydraulic pressure by feedback control according to a difference between the target gear ratio and the actual gear ratio, and performing a shift control based on the reference pulley hydraulic pressure and the feedback hydraulic pressure;
In a shift control device for a belt-type continuously variable transmission comprising:
The shift control means stops the feedback control when the vehicle speed is less than a predetermined value that cannot sufficiently ensure the accuracy due to the detection resolution of the vehicle speed sensor, and the thrust ratio is the lowest gear ratio, In addition, the lowest speed ratio can be achieved regardless of the input torque, and the shift control is performed by setting a predetermined thrust ratio lower than the thrust ratio set when the input torque is zero. Shift control device for belt type continuously variable transmission.

Images