JP7366494B2 - Shift control device for belt type continuously variable transmission - Google Patents

Description

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

Conventionally, in the shift pressure control of a belt-type continuously variable transmission, Patent Document 1 discloses that while the difference between the target gear ratio and the actual gear ratio is feedback-controlled, the control of the variable pulley is controlled based on a predetermined shift differential thrust characteristic. A technique has been disclosed that performs feedforward control of thrust and performs learning control of shift differential thrust characteristics related to feedforward control based on the control amount of feedback control in shift pressure control performed in the past. Further, it is disclosed that by changing the shift differential thrust characteristic using a feedback control amount at the time of shifting as a learning value, feedforward control is performed in accordance with the shift differential thrust characteristic for each unit.

Japanese Patent Application Publication No. 2012-241799

However, since the characteristics of the continuously variable transmission change each time the gear is changed, or due to differences in rotational speed or oil pressure, learning control for feedforward control must be implemented only after the feedback control amount has been accumulated. It took time for the control to stabilize, making it difficult to achieve the target operating performance.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a speed change control device for a belt-type continuously variable transmission that can achieve stable speed change control.

In order to achieve the above object, the speed change control device for a belt type continuously variable transmission of the present invention includes a belt type continuously variable transmission including a primary pulley, a secondary pulley, and a belt wound around both pulleys.
A balance thrust ratio, which is a ratio of pulley oil pressures supplied to the hydraulic chambers of each pulley, is calculated based on the input torque to the belt type continuously variable transmission and the target gear ratio, and a reference pulley oil pressure is calculated based on the balance thrust ratio. and a shift control means that calculates a feedback oil pressure by feedback control according to the difference between the target gear ratio and the actual gear ratio, and performs gear change control based on the reference pulley oil pressure and the feedback oil pressure;
In a speed change control device for a belt-type continuously variable transmission,
When changing the target speed ratio to a second target speed ratio, the speed change control means sets the reference pulley oil pressure in advance and performs a stepless speed change according to the operating state at the second target speed ratio. The hydraulic pressure for balancing the machine is characterized in that the higher the rotation speed of the primary pulley, the larger the feedforward hydraulic pressure is added.

Therefore, even if the characteristics of the belt type continuously variable transmission change depending on the operating state, stable speed change control can be achieved while ensuring responsiveness.

1 is a system diagram showing a speed change control device for a belt-type continuously variable transmission according to a first embodiment; FIG. FIG. 3 is a control block diagram illustrating a shift control process according to the first embodiment. 3 is a map showing characteristics of secondary oil pressure with respect to required torque in Embodiment 1. FIG. 2 is a torque ratio-thrust ratio map used for speed change control of the belt type continuously variable transmission of Embodiment 1. It is a map showing the secondary rotation speed compensation amount HNsec based on the secondary rotation speed of Embodiment 1. 3 is a map representing a secondary pressure compensation amount HPsec based on the secondary pressure of the first embodiment. 3 is a map showing the gear ratio compensation amount HGb based on the actual gear ratio of the first embodiment. It is a map showing the primary rotational speed compensation amount HNpri based on the primary rotational speed of Embodiment 1. 7 is a flowchart representing integral component control processing performed by the integrator of the first embodiment. FIG. 7 is a diagram showing variations in the integral compensation amount in feedback control when the primary rotational speed compensation amount based on the primary rotational speed is not added to the feedforward oil pressure of Embodiment 1, and when it is added. 5 is a time chart showing the relationship between the compensation amount H and the deviation ΔG during shift control according to the first embodiment.

[Embodiment 1]
FIG. 1 is a system diagram showing a speed change control device for a belt type continuously variable transmission according to a first embodiment. The vehicle of 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 drive wheels 8 via a differential gear 7. The belt-type continuously variable transmission consists of a transmission input shaft 2 connected to the crankshaft of the engine 1, a primary pulley 3 that rotates together with the transmission input shaft 2, and a secondary pulley that rotates together with the transmission output shaft 6. It has a pulley 5 and a belt 4 wound between the primary pulley 3 and the secondary pulley 5 to transmit power.

The primary pulley 3 includes a fixed sheave 3a formed integrally with the transmission input shaft 2, and a movable sheave 3b movable on the axis of the transmission input shaft 2. The movable sheave 3b is provided with a primary hydraulic chamber 3b1, and the primary hydraulic pressure Ppri supplied to the primary hydraulic chamber 3b1 generates a pressing force between the fixed sheave 3a and the movable sheave 3b to sandwich 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 axis of the transmission output shaft 6. The movable sheave 5b is provided with a secondary hydraulic chamber 5b1, and the secondary hydraulic pressure Psec supplied to the secondary hydraulic chamber 5b1 generates a pressing force between the fixed sheave 5a and the movable sheave 5b to sandwich the belt 4.

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

FIG. 2 is a control block diagram showing shift control processing within 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 target vehicle speed signal VSP. This target gear ratio Ga is determined based on a gear change characteristic set in advance so that the engine 1 achieves optimal fuel efficiency. Further, when fixed speed ratio control is requested from the shift lever or shift switch, fixed speed ratio control is performed to change the speed ratio in steps. The torque ratio calculation unit 202 calculates a torque ratio Qt, which is the ratio of the engine torque TENG to the torque Tmax (see FIG. 3) corresponding to the secondary oil pressure set based on the required torque TD.

The actual speed ratio calculation unit 203 reads the actual primary rotation speed Npri detected by the primary rotation speed sensor 23 and the actual secondary rotation speed Nsec detected by the secondary rotation speed sensor 24, and calculates the actual speed ratio Gb.

The gear ratio feedforward control unit 204 calculates a feedforward oil pressure Pff based on the target gear ratio Ga, and outputs it to the addition unit 207, which will be described later.

The gear ratio feedback control section 205 includes a deviation calculation section 205a, a proportional device 205b, a differentiator 205c, an integrator 205d, and an addition section 205e. The deviation calculation unit 205a calculates the deviation ΔG between the target speed ratio Ga and the actual speed ratio Gb. The proportional device 205b calculates a proportional component by multiplying the detected deviation ΔG by a proportional gain. The differentiator 205c differentiates the detected deviation ΔG, multiplies it by a differential gain, and calculates a differential component. The integrator 205d multiplies the detected deviation ΔG by an integral gain and integrates it to calculate an integral component Ix. As a result, a hydraulic pressure (hereinafter referred to as feedback hydraulic pressure Pfb) that is added to or subtracted from the primary hydraulic pressure Ppri and the secondary hydraulic pressure Psec is outputted by PID control. The adding unit 205e adds the components output from the proportional device 205b, the differentiator 205c, and the integrator 205d, and outputs the result as a feedback pressure Pfb. Note that details of the integrator 205d will be described later.

The balance thrust control unit 206 calculates the balance 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-balance thrust ratio map used for speed change control of the belt type continuously variable transmission of the first embodiment. A characteristic is selected based on the target gear ratio Ga, and a balance thrust ratio Qf is calculated from the selected characteristic and the torque ratio Qt. Next, a reference secondary oil pressure Psecb, 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 this reference secondary oil pressure Psecb is multiplied by the balance thrust ratio Qf to obtain the reference primary oil pressure. Calculate Pprib. Hereinafter, the reference secondary oil pressure Psecb and the reference primary oil pressure Pprib will be collectively referred to as the reference pulley oil pressure Pb.

In the balance compensator 208, a low-pass filter 24a for noise cutting is applied to the target gear ratio Ga (or the actual gear ratio Gb), the actual secondary oil pressure Psec, and the sensor signal detected by the secondary rotation speed sensor 24. Input the passed secondary rotation speed Nsec and the primary rotation speed Npri, which is the target gear ratio Ga multiplied by the secondary rotation speed Nsec (the primary rotation speed Npri detected by the primary rotation speed sensor 23 may also be used), and set the values for each parameter. A feedforward compensation oil pressure Pbf (hereinafter referred to as compensation amount H) for balancing the belt-type continuously variable transmission is calculated from a preset map according to the operating state.

FIG. 5 is a map showing the secondary rotational speed compensation amount HNsec based on the actual secondary rotational speed of the first embodiment. It is set so that the larger the actual secondary rotation speed Nsec is, the larger the secondary rotation speed compensation amount HNsec is.
FIG. 6 is a map showing the secondary pressure compensation amount HPsec based on the secondary pressure of the first embodiment. The smaller the actual secondary oil pressure Psec is, the more negative the compensation amount is output, and when the actual secondary oil pressure is equal to or higher than the predetermined oil pressure, 0 is output.
FIG. 7 is a map showing the gear ratio compensation amount HGb based on the actual gear ratio of the first embodiment. When the actual speed ratio Gb is lower than the predetermined speed ratio, a negative compensation amount is output, and when the actual speed ratio Gb is higher than the predetermined speed ratio, a positive compensation amount is output.
FIG. 8 is a map representing the primary rotational speed compensation amount HNpri based on the primary rotational speed of the first embodiment. The larger the primary rotation speed Npri is, the larger the primary rotation speed compensation amount HNpri is set.

The maps shown in FIGS. 5 to 8 are set based on the results of extracting and analyzing correlated factors from tens of thousands of pieces of measurement data. It has been found that this factor is expressed in the form of a hydraulic pressure correction amount rather than a balance thrust ratio correction gain. Belt-type continuously variable transmissions have a map for calculating the balance thrust ratio, but the balance thrust may change due to changes in other parameters that cannot be written on the map for calculating the balance thrust ratio. has. Conventionally, these characteristic changes that cannot be expressed in detail have been compensated for by speed ratio feedback control. Here, responsiveness becomes a problem, for example, when introducing control that changes the gear ratio in steps, or when changing the gear ratio significantly in response to kickdown. If the feedback gain is set large in order to improve responsiveness, there is a risk of instability such as control divergence. Furthermore, if the feedback gain is suppressed to ensure robustness, it will take time to reach the target gear ratio. Therefore, in the first embodiment, when changing the target gear ratio, the amount of compensation caused by the four newly discovered parameters is added in advance, thereby reducing the amount of compensation through feedback control and ensuring robustness. The aim was to ensure responsiveness while

The multiplication unit 207 adds the reference pulley oil pressure Pb, the feedback oil pressure Pfb, and the compensation amount H, and outputs a primary oil pressure command value and a secondary oil pressure command value (hereinafter collectively referred to as pulley oil pressure command value). do.

Here, details of the integrator 205d of the gear ratio feedback control section 205 will be explained. The integrator 205d of the first embodiment receives the rate of change ΔGb of the actual gear ratio Gb and the specified integral value Ia that estimates the range of variation in balance deviation, and resets the integral component based on these two values. carry out judgments;
FIG. 9 is a flowchart showing integral component control processing performed by the integrator of the first embodiment.
In step S1, it is determined whether the speed of change ΔGb is equal to or greater than a predetermined value g1 representing a sudden shift. If it is determined to be a sudden shift at g1 or more, the process proceeds to step S2; otherwise, this flow ends. and calculate the normal integral integral.
In step S2, it is determined whether the absolute value |Ix| of the integral component is less than or equal to the specified integral value Ia. If it is less than Ia, there is no large steady deviation such as a hydraulic offset value, that is, there is only a balance deviation. If it is determined that a large steady-state deviation has occurred, the process proceeds to step S3, and if it is larger than Ia, it is determined that a large steady-state deviation has occurred, and this flow is ended to calculate a normal integral component.
In step S3, the integral component Ix is reset.

Details of the control within the integrator 205d will be explained. In the first embodiment, since the compensation amount H is provided based on four parameters, the deviation ΔG to be compensated for by feedback control is made less likely to occur. However, in the case of continuous gear changes, it is assumed that an integral component Ix is accumulated in the integrator 205d during the process of shifting from the previous gear ratio to the next gear ratio. For example, if a downshift is performed in a state where a positive value has been accumulated as the integral component Ix due to an upshift, a negative value is preferably used as the integral component Ix. However, if a large positive value is set for the integral component Ix, it will take time to perform the subtraction, which may reduce responsiveness. Therefore, in the first embodiment, responsiveness can be ensured by resetting the integral component Ix to 0 when there is a sudden shift request.

FIG. 10 is a diagram showing variations in the integral compensation amount in feedback control when the primary rotational speed compensation amount based on the primary rotational speed is not added and when it is added in the feedforward control of the first embodiment. If the primary rotational speed compensation amount HNpri based on the primary rotational speed Npri is not added, the integral component Ix during feedback control is distributed over a wide range. On the other hand, when the primary rotational speed compensation amount HNpri is added, the integral component Ix is concentrated around 0. From this, it can be seen that the deviation ΔG during shift control occurs in a correlation with the primary rotation speed Npri. In other words, by providing the primary rotational speed compensation amount HNpri based on the primary rotational speed Npri during feedforward control, it is possible to reduce the amount of compensation by feedback control and ensure responsiveness while ensuring robustness.

FIG. 11 is a time chart showing the relationship between the compensation amount H and the deviation ΔG during the shift control according to the first embodiment. When the deviation ΔG is within the range, the compensation amount H obtained by adding HNsec, HPsec, and HGb is the value of H1. At time t1, when a downshift request is output, the deviation ΔG increases. Conventionally, changes in the characteristics of the belt-type continuously variable transmission due to changes in the operating point have not been taken into account, so gear ratio feedback control has had to be used. On the other hand, in Embodiment 1, the compensation amount H is changed to H2, so it is possible to compensate in advance for the amount corresponding to the change in the characteristics of the belt type continuously variable transmission, and the other amount can be compensated for by the gear ratio feedback. Since it only needs to be handled by control, it is possible to shift gears with high responsiveness.

At time t2, when an upshift is requested this time, the deviation ΔG becomes a negative value, and the necessary integral component Ix also takes a negative value. At this time, as at time t1, the compensation amount H is changed to H3 and the integral component Ix is reset to 0, so that the deviation ΔG can be immediately eliminated. Note that the same applies after time t3, so the explanation will be omitted.

As described above, resetting the integral component Ix is effective in ensuring responsiveness if a compensation amount is provided to balance the belt type continuously variable transmission at a desired speed ratio. However, if there is a large steady deviation that is not a balance deviation, such as an offset in the pulley oil pressure, the integral component Ix may accumulate to a large value even if the target gear ratio is constant. be. If the large integral component Ix accumulated at the time of a sudden shift request is reset all at once, it will not be possible to compensate for the pulley oil pressure offset, making it difficult to ensure the stability of shift control. Therefore, if the integral component Ix is greater than or equal to the predetermined value Ia estimated based on the range of variation in balance deviation, it is assumed that the integral component Ix has been constantly accumulated due to a large disturbance that is not a balance deviation, and resetting of the integral component Ix is prohibited. And so. Thereby, the stability of shift control can be further ensured.

As explained above, in Embodiment 1, the effects listed below can be obtained.
(1) A belt-type continuously variable transmission comprising 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). The thrust ratio, which is the ratio of the pulley oil pressure supplied to the hydraulic chamber of each pulley, is calculated based on the target gear ratio Ga, and the reference pulley oil pressure is calculated based on the thrust ratio, and the target gear ratio Ga and the actual gear ratio Gb are calculated. A transmission controller 20 (speed change control means) that calculates feedback oil pressure by feedback control according to the difference between the reference pulley oil pressure and the feedback oil pressure, and performs speed change control based on the reference pulley oil pressure and the feedback oil pressure. In the transmission control device, when changing the target transmission ratio to the second target transmission ratio, the transmission controller 20 sets the reference pulley oil pressure in advance and performs compensation according to the operating state at the second target transmission ratio Ga. A primary rotational speed compensation amount HNpri (feedforward hydraulic pressure) is added, which is the amount H (feedforward oil pressure for balancing the continuously variable transmission), which is larger as the rotational speed Npri of the primary pulley 3 is higher.
Therefore, even if the characteristics of the belt type continuously variable transmission change depending on the operating state, stable speed change control can be achieved while ensuring responsiveness.

(2) The actual secondary rotation speed compensation amount HNsec increases as the secondary rotation speed Nsec (value equivalent to the rotation speed of the secondary pulley) increases. Therefore, even if the characteristics of the balance thrust ratio of the belt type continuously variable transmission change depending on the secondary rotation speed Nsec, stable speed change control can be achieved by providing an appropriate compensation amount HNsec. Note that, instead of using the actual secondary rotation speed Nsec, the target secondary rotation speed Nsec*, the actual vehicle speed VSP, and the target vehicle speed VSP* may be used.
(3) The secondary oil pressure compensation amount HPsec is a negative value whose absolute value is larger as the secondary oil pressure Psec (secondary pulley oil pressure equivalent value) is smaller. Therefore, even if the characteristics of the balance thrust ratio of the belt type continuously variable transmission change depending on the secondary oil pressure Psec, stable speed change control can be achieved by providing an appropriate compensation amount HPsec. Note that, in addition to the actual secondary oil pressure Psec, target secondary oil pressure Psec*, actual engine torque TENG, target engine torque TENG*, target primary pressure Ppri*, or actual primary oil pressure Ppri may be used.
(4) The gear ratio oil pressure compensation amount HGb is a negative compensation amount HGb when the actual gear ratio Gb is lower than the predetermined gear ratio, and is a positive compensation amount HGb when it is higher than the predetermined gear ratio. Therefore, even if the characteristics of the balance thrust ratio of the belt type continuously variable transmission change depending on the actual speed ratio Gb, stable speed change control can be achieved by providing an appropriate compensation amount HGb. Note that the target speed ratio Ga may be used instead of the actual speed ratio Gb.

(5) When the rate of change ΔGb of the actual gear ratio Gb is equal to or greater than a predetermined value g1 representing a sudden shift, the integral component Ix of the feedback control is reset. Therefore, it is possible to further ensure responsiveness and achieve stable shift control. Note that instead of using the actual gear ratio Gb, the rate of change ΔGa of the target gear ratio Ga may be used.

(6) Integral of Feedback Control If the absolute value |Ix| of the integral is equal to or greater than a predetermined value Ia representing the range of variation in balance deviation, resetting of the integral component Ix is prohibited. Therefore, it is possible to further ensure responsiveness and achieve stable shift control. Note that the target gear ratio Ga may be used instead of the actual gear ratio Gb, and the upper and lower limits of the predetermined value Ia representing the estimated balance deviation may be set to different values. . That is, when the integral component of the feedback control is outside a predetermined range representing the range of variation in balance deviation, resetting of the integral component of the feedback control is prohibited.

(Other examples)
The above description has been made based on the first embodiment, but the present invention is not limited to the above embodiment, and other configurations are also included in the present invention. Although the first embodiment shows an example in which the balance thrust ratio is calculated according to the torque ratio, a configuration may be adopted in which the balance thrust ratio is calculated according to the target gear ratio and the input torque.

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
20 Transmission controller
30 Control valve unit
205 Gear ratio feedback control section
208 Balance compensator

Claims (6)

A belt-type continuously variable transmission including a primary pulley, a secondary pulley, and a belt wound around both pulleys;
A balance thrust ratio, which is a ratio of pulley oil pressures supplied to the hydraulic chambers of each pulley, is calculated based on the input torque to the belt type continuously variable transmission and the target gear ratio, and a reference pulley oil pressure is calculated based on the balance thrust ratio. and a shift control means that calculates a feedback oil pressure by feedback control according to the difference between the target gear ratio and the actual gear ratio, and performs gear change control based on the reference pulley oil pressure and the feedback oil pressure;
In a speed change control device for a belt-type continuously variable transmission,
When changing the target speed ratio to a second target speed ratio , the speed change control means controls the speed of each pulley based on the input torque to the belt type continuously variable transmission and the second target speed ratio. A balance thrust ratio, which is a ratio of pulley oil pressure supplied to the hydraulic chamber, is calculated, and the reference pulley oil pressure calculated based on the balance thrust ratio is set in advance and according to the operating state at the second target gear ratio. A shift control device for a belt-type continuously variable transmission, characterized in that a feedforward oil pressure is added to the hydraulic pressure for balancing the belt-type continuously variable transmission, which increases as the rotational speed of the primary pulley increases. The speed change control device for a belt type continuously variable transmission according to claim 1,
Shift control of a belt-type continuously variable transmission , wherein the feedforward oil pressure is a larger oil pressure as the rotational speed of the primary pulley is higher, and the feedforward oil pressure is larger as the rotational speed equivalent value of the secondary pulley is higher. Device. The speed change control device for a belt type continuously variable transmission according to claim 1 ,
The belt type continuously variable transmission is characterized in that the feedforward oil pressure is a larger oil pressure as the rotation speed of the primary pulley is higher, and is a negative oil pressure whose absolute value is larger as the oil pressure equivalent value of the secondary pulley is smaller. Machine speed control device. The speed change control device for a belt type continuously variable transmission according to claim 1 ,
The feedforward oil pressure is a larger oil pressure as the rotation speed of the primary pulley is higher, and is a negative oil pressure when the gear ratio is lower than a predetermined gear ratio, and positive when the gear ratio is higher than a predetermined gear ratio. A speed change control device for a belt-type continuously variable transmission characterized by hydraulic pressure. The speed change control device for a belt type continuously variable transmission according to any one of claims 1 to 4,
A speed change control device for a belt type continuously variable transmission, characterized in that an integral component of the feedback control is reset when the speed change rate of the speed ratio is equal to or higher than a predetermined value representing a sudden speed change. The speed change control device for a belt type continuously variable transmission according to any one of claims 1 to 5,
A speed change control device for a belt-type continuously variable transmission, wherein resetting of the integral component of the feedback control is prohibited when the integral component of the feedback control is outside a predetermined range representing an estimated value of a balance deviation.

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