JP6503956B2 - Electric current control method, electric current control device, and hydraulic control device for automatic transmission - Google Patents

Description

  The present invention relates to technology for controlling the current of a solenoid valve.

  Conventionally, for example, the technique described in Patent Document 1 superimposes a dither signal on a current command value of a solenoid valve.

JP, 2010-276077, A

  However, there is room to improve the control accuracy of the solenoid valve. An object of the present invention is to improve control accuracy of a solenoid valve.

For this purpose, the current control method according to the embodiment of the present invention superimposes the dither signal on the current command value, and in the area where the current command value is large, the size is larger than the area where the current command value is small. In a region where the current command value is large, an offset signal having a larger amount of change with respect to a change in the current command value is superimposed on the current command value than in a region where the current command value is small .

  Therefore, the control accuracy of the solenoid valve can be improved.

FIG. 2 is a system diagram showing a hydraulic control device of the continuously variable transmission mechanism of the embodiment. It is a block diagram which shows the current control part of the CVT control unit of embodiment. It is a graph which shows an example of the solenoid characteristic of an embodiment. It is a block diagram showing a hysteresis correction compensator of an embodiment. It is an example of the map for calculating the offset signal of embodiment. It is an example of the map for calculating the dither signal (amplitude) of embodiment. It is a time chart which shows the response of the pulley pressure to the solenoid current of an embodiment. It is a time chart which shows the response of the pulley pressure to the solenoid current of a comparative example.

  Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings.

[Constitution]
First, the configuration will be described. FIG. 1 is a system diagram showing a part of a drive system of a vehicle of the present embodiment and a hydraulic control device of a continuously variable transmission mechanism 7. The vehicle is a car. The drive system includes an engine (motor) 3, which is a drive source of the vehicle, a transmission system 4, a final gear (not shown), a differential gear (not shown), and drive wheels (not shown). The hydraulic control device includes a hydraulic control mechanism 2 and a CVT control unit 1. The engine 3 is an internal combustion engine, and a gasoline engine, a diesel engine or the like can be used. The transmission system 4 includes a torque converter 5, a forward / reverse switching mechanism 6, and a continuously variable transmission mechanism 7 as an automatic transmission. The torque converter 5 is a power transmission device disposed downstream of the engine 3 and is a fluid coupling having a torque amplification function. The forward / reverse switching mechanism 6 is a power transmission device disposed downstream of the torque converter 5 and has a forward clutch and a reverse brake. The forward / reverse switching mechanism 6 can switch and input the direction of rotation (in the forward rotation direction during forward traveling and the reverse direction during reverse traveling). The continuously variable transmission mechanism 7 is a power transmission device disposed downstream of the forward / reverse switching mechanism 6 and is a transmission unit capable of changing and inputting the speed (torque) of the input rotation. The rotation (torque, rotational driving force) from the engine 3 is input to the continuously variable transmission mechanism 7 through the torque converter 5 and the forward / reverse switching mechanism 6. The rotation input to the continuously variable transmission mechanism 7 is shifted at a desired gear ratio in the continuously variable transmission mechanism 7 and then output to the drive wheels via a final gear or the like located on the rear stage side. The vehicle travels by driving the drive wheels.

  The continuously variable transmission mechanism 7 is a belt-type continuously variable transmission CVT, and has a continuously variable transmission function that continuously changes the ratio between the rotation speed of the input shaft 70p and the rotation speed of the output shaft 70s. The continuously variable transmission mechanism 7 includes a pair of pulleys (a primary pulley 71 p and a secondary pulley 71 s) and a belt 72 wound around them. The primary pulley 71 p is a pulley on the input side (drive side), and receives rotational drive force from the engine 3 (via the torque converter 5). The secondary pulley 71 s is a pulley on the output side (following side), and outputs the rotational driving force transmitted from the primary pulley 71 p side via the belt 72. The pulley 71 comprises a fixed (fixed) sheave 710 and a movable (slide) sheave 711. The fixed sheave 710 is fixed to the rotating shaft 70 and rotates integrally with the rotating shaft 70. The movable sheave 711 is movable in the axial direction of the rotating shaft 70 and is restricted in movement in the rotational direction, and rotates integrally with the rotating shaft 70. A V-shaped pulley groove 73 is formed between the fixed sheave 710 and the movable sheave 711. A hydraulic fluid chamber 74 is defined on the back side of the movable sheave 711 (opposite to the pulley groove 73 in the axial direction). The hydraulic pressure is supplied from the hydraulic control mechanism 2 to the hydraulic fluid chamber 74.

  The hydraulic control mechanism 2 can supply hydraulic pressure for controlling the operation of the continuously variable transmission mechanism 7 to the continuously variable transmission mechanism 7. The hydraulic control mechanism 2 has a hydraulic circuit 20 and also has an oil pump 21 and a plurality of control valves 22 to 25 as hydraulic actuators. The oil pump 20 is a hydraulic pressure source driven by the engine 3. The control valve includes a first pressure regulating valve (regulator valve) 22, a second pressure regulating valve 23, a primary solenoid valve 24p, a secondary solenoid valve 24s, a primary pressure regulating valve 25p, and a secondary pressure regulating valve 25s. The solenoid valve 24 has a solenoid, a plunger (movable core) driven by the solenoid, a fixed core, and a return spring. The solenoid is a proportional solenoid. When a current (drive current) is supplied to the solenoid, a force is generated which electromagnetically attracts the plunger to the stationary core. The return spring always generates a biasing force that pulls the plunger away from the stationary core. By reciprocating the plunger according to the magnitude relationship between the suction force and the biasing force, the position of the plunger, that is, the valve opening degree (valve opening amount) in the opening direction and the closing direction is linearly adjusted. In the present embodiment, the solenoid valve 24 is a normally closed valve, and the larger the current (hereinafter referred to as the solenoid current I) supplied to the solenoid, the larger the valve opening degree.

  The hydraulic circuit 20 has a line pressure oil path 200, a pilot pressure oil path 201, a pulley pressure (working pressure) oil path 202, and a signal pressure oil path 203. The line pressure oil passage 200 is connected to the discharge side of the oil pump 20. The line pressure oil passage 200 is provided with a first pressure regulating valve 22. The pilot pressure oil passage 201 is connected to the downstream side of the first pressure regulating valve 22 in the line pressure oil passage 200. The pilot pressure oil passage 201 is provided with a second pressure regulating valve 23. The pulley pressure oil passage 202 is connected to the downstream side of the connection portion of the pilot pressure oil passage 201 in the line pressure oil passage 200. The pulley pressure oil passage 202 has a primary pulley pressure oil passage 202p and a secondary pulley pressure oil passage 202s. The primary pulley pressure oil passage 202p is connected to the hydraulic oil chamber 74p of the primary pulley 71p, and the secondary pulley pressure oil passage 202s is connected to the hydraulic oil chamber 74s of the secondary pulley 71s. A primary pressure regulating valve 25p is provided in the primary pulley pressure oil passage 202p, and a secondary pressure regulating valve 25s is provided in the secondary pulley pressure oil passage 202s. The signal pressure oil passage 203 is connected to the downstream side of the second pressure regulating valve 23 in the pilot pressure oil passage 201. The signal pressure oil passage 203 has a primary signal pressure oil passage 203p and a secondary signal pressure oil passage 203s. The primary signal pressure oil passage 203p is connected to the primary pressure regulating valve 25p, and the secondary signal pressure oil passage 203s is connected to the secondary pressure regulating valve 25s. A primary solenoid valve 24p is provided in the primary signal pressure oil passage 203p, and a secondary solenoid valve 24s is provided in the secondary signal pressure oil passage 203s.

  The CVT control unit 1 is an electronic control unit, and outputs a command signal to the hydraulic control mechanism 2 to perform gear ratio control. The CVT control unit 1 determines a target gear ratio according to the driving state of the vehicle (the input rotational speed of the continuously variable transmission mechanism 7, the accelerator opening degree, etc.), or a target shift determined according to the driving state of the vehicle. Receiving the input of the ratio and realizing the target gear ratio, the hydraulic pressure of the hydraulic oil chamber 74p of the primary pulley 71p (primary pulley pressure Pp) and the hydraulic pressure of the hydraulic oil chamber 74s of the secondary pulley 71s (secondary pulley pressure Ps) Control. The hydraulic control mechanism 2 adjusts the primary pulley pressure Pp and the secondary pulley pressure Ps independently of each other in response to a command from the CVT control unit 1. The oil pump 20 pumps hydraulic fluid to supply the discharge pressure to the line pressure oil passage 200. The first pressure regulating valve 22 regulates the discharge pressure to generate a line pressure. The line pressure is supplied to the pilot pressure oil passage 201 and the pulley pressure oil passage 202. The second pressure regulating valve 23 regulates the line pressure to generate a pilot pressure. The pilot pressure is supplied to the signal pressure oil passage 203. Primary solenoid valve 24p regulates pilot pressure to generate primary signal pressure. The primary signal pressure is supplied to the primary pressure regulating valve 25p. The secondary solenoid valve 24s regulates the pilot pressure to generate a secondary signal pressure. The secondary signal pressure is supplied to the secondary pressure regulating valve 25s. The primary pressure regulating valve 25 p regulates the line pressure to generate a primary pulley pressure Pp according to the primary signal pressure. Primary pulley pressure Pp is supplied to hydraulic fluid chamber 74p of primary pulley 71p. The secondary pressure regulating valve 25s regulates the line pressure to generate a secondary pulley pressure Ps corresponding to the secondary signal pressure. The secondary pulley pressure Ps is supplied to the hydraulic oil chamber 74s of the secondary pulley 71s. The CVT control unit 1 controls the current of the solenoids of the primary solenoid valve 24p and the secondary solenoid valve 24s to control the degree of opening of these valves 24p and 24s, and the desired primary signal pressure and secondary signal from the pilot pressure Generate pressure.

  The pulley pressure P is a hydraulic pressure (hydraulic pressure) that operates the continuously variable transmission mechanism 7. That is, the movable sheave 711 is pushed toward the fixed sheave 710 by the pulley pressure P, and the belt 72 is nipped by the pulley groove 73. That is, in the pulley groove 73, the belt 72 is nipped between the sheaves 710 and 711 on both sides in the rotational axis direction. Thus, power transmission is performed between the pulleys 71p and 71s via the belt 72. The movable sheave 711 moves (slides) in the axial direction of the rotating shaft 70 in accordance with the hydraulic pressure of the hydraulic fluid chamber 74. The movement of the movable sheave 711 changes the pulley groove width. The pulley groove width is controlled by adjusting the hydraulic pressure of the hydraulic fluid chamber 74. As the pulley groove width changes continuously, the contact radius between the belt 72 and the pulley 71 (winding radius of the belt 72) changes continuously. The ratio Rs / Rp of the winding radius Rp of the belt 72 to the primary pulley 71p and the winding radius Rs of the belt 72 to the secondary pulley 71s corresponds to a transmission ratio. By changing the pulley groove widths of the pulleys 71p and 71s independently of each other, the transmission ratio (pulley ratio) when transmitting the rotational drive force from the primary pulley 71p (input shaft 70p) to the secondary pulley 71s (output shaft 70s) Is changed steplessly. For example, during power transmission, the movable sheave 711p of the primary pulley 71p is moved away from the fixed sheave 710p to widen the pulley groove width of the primary pulley 71p, while the movable sheave 711s of the secondary pulley 71s is brought closer to the fixed sheave 710s and the secondary pulley 71s Narrow the pulley groove width. As a result, Rp decreases while Rs increases. As a result, the pulley ratio is changed to the low side and downshifting is possible. The pulley ratio is changed to the high side by performing the operation reverse to the above with both pulleys 71p and 71s, and the upshift is possible.

  As described above, the CVT control unit 1 achieves the shift of the continuously variable transmission mechanism 7 by controlling the current supplied to each solenoid. The transmission gear ratio is determined by the pulley pressure P applied to each pulley 71p, 71s from each pressure adjustment valve 25p, 25s according to the signal pressure from each solenoid valve 24p, 24s. That is, the CVT control unit 1 functions as a current control device, and controls the current of the solenoid of each solenoid valve 24p, 24s to control the opening degree (each signal pressure) of these valves 24p, 24s. Thereby, the opening degree of each pressure regulation valve 25p, 25s is adjusted, and each pulley pressure Pp, Ps is controlled. The CVT control unit 1 has a current control unit 10 that controls the current I of each solenoid (drive current supplied to the solenoid coil). FIG. 2 is a block diagram showing the current control unit 10 together with the control target 100. As shown in FIG. The current control unit 10 first sets a current command value Icmd. Icmd is set according to each pulley pressure Pp, Ps (that is, target pulley pressure Pp *, Ps *) that realizes the determined target gear ratio.

  Here, there is friction in a sliding portion such as a plunger or the like in the solenoid valve 24, and due to this friction or the like, an opening degree (valve opening amount) of the solenoid valve 24 or a position between the plunger and the solenoid current I There is a hysteresis characteristic (a phenomenon in which the opening degree of the solenoid valve 24 differs between the increasing direction and the decreasing direction of I). FIG. 3 is a graph showing an example of a result of experimentally measuring static characteristics between the solenoid current I and the pulley pressure P. As shown in FIG. As I increases from the side of 0, P rises, and as I decreases to the side of 0, P decreases. Hereinafter, it is assumed that the current I changing in the increasing direction is Iinc and the current I changing in the decreasing direction is Idec. The opening degree of the solenoid valve 24 corresponds to P. As apparent from FIG. 3, a hysteresis characteristic exists between P and I, and I with respect to P has a difference (hysteresis difference or hysteresis width) ΔIhys due to the hysteresis characteristic. Iinc when the predetermined P is obtained is larger than Idec when the predetermined P is obtained. In other words, Idec when the predetermined P is obtained is smaller than Iinc when the predetermined P is obtained. When the direction of change of I is switched from increase to decrease at any I, P starts to decrease only after I decreases from the value Iinc at the time of switching to Idec (= Iinc−ΔIhys) smaller by ΔIhys. When the change direction of I is switched from decrease to increase, P starts to rise only after I increases from the value Idec at the time of switching to Iinc (= Idec + ΔIhys) which is larger by ΔIhys.

  Further, in a region where the amount of movement of the plunger is large, the suction force (thrust) acting on the plunger becomes small. The hysteresis difference ΔIhys differs depending on the amount of movement (valve opening) of the plunger due to the suction force difference and the like, and the larger the amount of movement of the plunger, the larger ΔIhys. In the region where P (or I) is large, ΔIhys is larger than in the region where P (or I) is small. As P (or I) increases, ΔIhys increases. Specifically, in a region where P is larger than predetermined value P1 (a region where I is larger than the vicinity of predetermined value I1), P is smaller than in a region where P is smaller than P1 (a region where I is smaller than I1). Along with a large change in I with respect to change (change per unit) dI / dP is large (small change in P with respect to change in I dP / dI is small), ΔIhys is large, and ΔIhys with respect to change in P (or I) The amount of change dΔIhys / dP (or dΔIhys / dI) is large.

  The current command value Icmd is a command current value set on the premise that there is no friction in the sliding portion of the solenoid valve 24 and there is no hysteresis characteristic. Specifically, Icmd is a value substantially in the middle between Iinc and Idec corresponding to the target pulley pressure P *.

Vcmd_FINを印加されたソレノイドには、上記式(1)の伝達特性に従ってIrealが流れる。Irealの値は電流制御部10に入力され、電流制御部10はIrealを検知する。 The current control unit 10 calculates a final voltage command value Vcmd_FIN from the current command value Icmd, and applies this to the solenoid (coil) which is the control target 100. The control target 100 indicates the actual electrical characteristics of the solenoid of the solenoid valve 24. The transfer characteristic from Vcmd_FIN to the real current Ireal of the solenoid is expressed by the following equation (1). s is the Laplace operator. L is the inductance of the coil of the solenoid and R is the resistance of the coil.

In the solenoid to which Vcmd_FIN is applied, Ireal flows according to the transfer characteristic of the above equation (1). The value of Ireal is input to the current control unit 10, and the current control unit 10 detects Ireal.

  Hereinafter, a process of calculating the final voltage command value Vcmd_FIN from the current command value Icmd will be specifically described. The current control unit 10 includes a hysteresis correction compensator 11, a reference response calculator 12, a feedforward compensator 13, a feedback compensator 14, a first robust compensator 15, and a second robust compensator 16. . In addition, the current control unit 10 includes a first subtractor 171, a second subtractor 172, a first adder 181, and a second adder 182.

  The hysteresis correction compensator 11 calculates a hysteresis correction current command value Icmd_hys from the current command value Icmd. Details will be described later.

The reference response calculator 12 calculates a reference response Iref from the hysteresis correction current command value Icmd_hys by the following equation (2). Iref is a designer's desired current response. Tref is a first-order lag time constant.

The feedforward compensator 13 calculates a feedforward voltage command value Vcmd_FF from the hysteresis correction current command value Icmd_hys according to the following equation (3). Vcmd_FF is a voltage command value that realizes the reference response Iref. The equation (3) is obtained by multiplying the inverse system of the transfer characteristic of the control target 100 of the equation (1) by the reference response of the equation (2).

  The first subtractor 171 subtracts the actual current Ireal from the reference response Iref to calculate the difference between the two (Iref−Ireal).

The feedback compensator 14 receives the deviation (Iref−Ireal), and calculates a feedback voltage command value Vcmd_FB according to the following equation (4). K is a feedback gain.

  The first adder 181 adds the feedforward voltage command value Vcmd_FF and the feedback voltage command value Vcmd_FB to calculate the sum (Vcmd_FF + Vcmd_FB) of the two.

The second adder 182 adds (Vcmd_FF + Vcmd_FB) and a robust voltage command value Vcmd_ROB described later according to the following equation (5) to calculate a final voltage command value Vcmd_FIN.

The first robust compensator 15 receives the final voltage command value Vcmd_FIN, and calculates a first robust voltage command value Vcmd_ROB_1 from the following equation (6). T _H is a robust cutoff frequency.

The second robust compensator 16 receives the actual current Ireal, and calculates a second robust voltage command value Vcmd_ROB_2 from the following equation (7).

The second subtractor 172 subtracts the second robust voltage command value Vcmd_ROB_2 from the first robust voltage command value Vcmd_ROB_1 according to the following equation (8) to calculate a (final) robust voltage command value Vcmd_ROB.

  Finally, by applying the final voltage command value Vcmd_FIN to the solenoid, the solenoid current Ireal is controlled to the hysteresis correction current command value Icmd_hys while realizing the reference response Iref desired by the designer.

  Next, the hysteresis correction compensator 11 will be described. FIG. 4 is a block diagram showing the hysteresis correction compensator 11. The hysteresis correction compensator 11 includes an offset standard response calculation unit 110, a change calculation unit 111, a sign determination unit 112, an argument calculation unit 113, an offset signal calculation unit 114, a dither amplitude calculation unit 115, and a dither signal. An arithmetic unit 116 and a hysteresis correction current command value arithmetic unit 117 are included.

The offset reference response calculation unit 110 calculates a current reference response Iref_ofs for offset according to the following equation (9) from the current command value Icmd. Formula (9) is isomorphic to said Formula (2).

The change calculation unit 111 calculates a change Idot of the offset reference response Iref_ofs according to the following expression (10). Td is an approximate differential time constant.

  The code determination unit 112 determines the code of the reference response change Idot based on Idot / | Idot |.

ただし、Idotが０の場合は、引数演算部113は、Icmd_xの符号として、前回サンプルの計算値を使う。 The argument calculation unit 113 calculates an offset map argument Icmd_x by integrating the current command value Icmd and the sign of the change Idot according to the following expression (11).

However, when Idot is 0, the argument operation unit 113 uses the calculated value of the previous sample as the sign of Icmd_x.

  The offset signal operation unit 114 performs a lookup operation on the offset signal Ioffset based on the map shown in FIG. 5 from the offset map argument Icmd_x. Ioffset is an offset (current offset) with respect to the current command value Icmd, and is a current signal that causes Icmd to be continuously offset to a side larger or smaller than the original value by being superimposed on Icmd. Icmd is 0 or positive. If the sign of Idot is positive (Icmd changes in the increasing direction), Icmd_x becomes a positive value according to the size of Icmd. In the first quadrant of the graph in the map of FIG. 5, Ioffset is determined according to Icmd_x. If the sign of Idot is negative (Icmd changes in the decreasing direction), Icmd_x is a negative value corresponding to the size of Icmd. In the third quadrant of the graph, Ioffset according to Icmd_x is determined. In the map, when Icmd_x is positive, Ioffset increases (proportionally) as Icmd_x increases in the first area α (area where Icmd is small) from Icmd_x 0 to a predetermined value Icmd1. Ioffset is a predetermined value Ioffset0 when Icmd_x is 0, and is a predetermined value Ioffset1 (> Ioffset0) when Icmd_x is Icmd1. Ioffset becomes larger (proportionally) as Icmd_x becomes larger in the second region β where Icmd_x is Icmd1 or more (a region where Icmd is large). The amount of change in Ioffset with respect to the change in Icmd_x in the second region β is larger than the amount of change d Ioffset / d Icmd_x in the first region α.

  When Icmd_x is negative, Ioffset becomes smaller (proportionally) as Icmd_x becomes smaller in the third region γ (region where Icmd is smaller) from Icmd_x to 0 to −Icmd1. Ioffset is −Ioffset0 when Icmd_x is 0, and is −Ioffset1 (<−Ioffset0) when Icmd_x is −Icmd1. Ioffset becomes smaller (proportionally) as Icmd_x becomes smaller in the fourth region δ where Icmd_x is less than or equal to −Icmd1 (region where Icmd is large). The size of d Ioffset / d Icmd_x in the third region γ is substantially the same as the size of d Ioffset / d Icmd_x in the first region α. The magnitude of d Ioffset / d Icmd_x in the fourth region δ is substantially the same as the magnitude of d Ioffset / d Icmd_x in the second region β. Icmd1 in the map is set to the predetermined value I1 of FIG. That is, the offset signal operation unit 114 obtains ΔIhys of FIG. 3 in advance, and in the region of Icmd where the ΔIhys is large (second and fourth regions β, δ), the region of Icmd where the ΔIhys is small (first, third regions The Ioffset is made larger than in α, γ), and the amount of change in Ioffset with respect to the change in Icmd d Ioffset / d Icmd is made larger.

  The dither amplitude calculator 115 performs a lookup operation on the dither amplitude Adiz based on the map shown in FIG. 6 from the current command value Icmd. In the map, Adiz increases (proportionally) as Icmd increases in a range from Icmd of 0 to a predetermined value Icmd2. Icmd2 is set to a value slightly larger than the above Icmd1. Adiz is 0 when Icmd is 0, and becomes maximum Adiz_max when Icmd is Icmd2. In the region where Icmd is Icmd2 or more, Adiz is Adiz_max regardless of Icmd.

The dither signal calculation unit 116 calculates a dither signal Idiz from the dither amplitude Adiz and the dither frequency Fdiz [Hz] according to the following equation (12). π is the circle ratio and t is time. Fdiz is preset. Idiz is a current signal that changes Icmd between the larger and smaller sides than the original value by being superimposed on Icmd.

オフセット信号Ioffsetの大きさ（電流指令値に対するオフセット量）とディザ振幅Adiz（ディザ信号の振幅量）との配分は、図５と図６に示すマップの設定値により、電流指令値Icmdに応じて決まる。 The hysteresis correction current command value calculation unit 117 adds (superimposes) the dither signal Idiz and the offset signal Ioffset to the current command value Icmd to calculate a hysteresis correction current command value Icmd_hys according to the following equation (13).

Distribution of the magnitude (offset amount to the current command value) of the offset signal Ioffset and the dither amplitude Adiz (amplitude amount of the dither signal) is made according to the current command value Icmd by the set values of the maps shown in FIGS. It is decided.

[Effect]
Next, the function and effect will be described. FIG. 7 is a time chart showing the response of the pulley pressure P when the solenoid current I is changed. The dashed-dotted line indicates Icmd, the dashed-dotted line indicates Icmd + Ioffset, and the solid line indicates Ireal (= Icmd_hys = Icmd + Idiz + Ioffset).

  From time t1 to time t4, the current command value Icmd is increased from 0 with a constant gradient. Icmd becomes Icmd1 at time t2 and becomes Icmd2 at time t3. Icmd is in the first region α of the map of FIG. 5 from time t1 to time t2, and is in the second region β from time t2 to time t4. From time t1 to time t4, the offset signal Ioffset is calculated by the offset signal calculation unit 114 using the first quadrant of the map of FIG. Ioffset gradually increases from Ioffset0 in response to an increase in Icmd from time t1 to time t2. Ioffset gradually increases from Ioffset1 in response to an increase in Icmd at an increase rate dIoffset / dt greater than time t2 from time t2 to time t2. The amplitude Adiz of the dither signal Idiz calculated by the dither amplitude calculator 115 using the map of FIG. 6 gradually increases from 0 from time t1 to time t3 in accordance with the increase of Icmd. Adiz remains at Adiz_max from time t3 to time t4. From time t1 to time t4, the actual current Ireal changes in a wave shape oscillating with an amplitude Adiz centering on Icmd + Ioffset. The actual pulley pressure P follows the target pulley pressure P * corresponding to Icmd.

  At time t4, (the change direction of) Icmd switches from increase to decrease. Ioffset added to Icmd switches from a positive value in the first quadrant of the map of FIG. 5 to a negative value in the third quadrant.

  From time t4 to time t7, Icmd is decreased to 0 with a constant slope. Icmd becomes Icmd2 at time t5 and becomes Icmd1 at time t6. Icmd is in the fourth region δ of the map of FIG. 5 from time t4 to time t6, and is in the third region γ from time t6 to time t7. Ioffset (negative value) gradually increases (to the side of 0) in response to the decrease of Icmd (increase of Icmd_x) from time t4 to time t6 (the magnitude decreases). Ioffset (negative value) gradually increases (decreases in size) from -Ioffset1 according to the decrease of Icmd, at an increase rate dIoffset / dt smaller than that from time t6 to time t7. Adiz remains at Adiz_max from time t4 to time t5. Adiz gradually decreases toward 0 from time t5 to time t7 in response to the decrease of Icmd. From time t4 to time t7, Ireal changes in a wave shape oscillating at an amplitude Adiz centering on Icmd + Ioffset. The actual P follows the P * corresponding to Icmd.

  The hydraulic control device using the solenoid valve 24 adjusts the valve opening degree to adjust the hydraulic pressure P by flowing a current I to the solenoid of the solenoid valve 24 and moving the plunger. In this hydraulic control, it is important to control the valve opening degree (plunger position) linearly by the solenoid current I. However, due to the presence of hysteresis characteristics (see FIG. 3) between I and the valve opening degree, linear valve opening degree control of the solenoid becomes difficult, and there is a possibility that high-precision hydraulic control can not be realized. On the other hand, in the present embodiment, the offset signal Ioffset is superimposed on the current command value Icmd. Therefore, the influence of the hysteresis characteristics can be suppressed, the control of the solenoid valve 24 can be stabilized, and the control accuracy of the solenoid valve 24 can be improved. Note that the current control of the present embodiment may be applied to control of solenoid valves other than the hydraulic control device of an automatic transmission. In the present embodiment, since the above current control is applied to control of the solenoid valve 24 in the hydraulic control device of the automatic transmission (stepless transmission mechanism 7), the accuracy of control of the pulley pressure Pp, Ps (gear ratio control) can be improved. .

  Specifically, when the change direction of the current I switches from an increase to a decrease, a hysteresis difference ΔIhys occurs in the direction in which I decreases (see FIG. 3). In this embodiment, when Icmd (the change direction of Icmd) switches from increase to decrease at time t4, Ioffset is superimposed on Icmd in the direction to decrease the size of Icmd. That is, a negative value Ioffset is added to Icmd, and a current command value Icmd obtained by subtracting the magnitude of Ioffset from the original Icmd is used. Therefore, since the solenoid current I is corrected to reduce ΔIhys, linear valve opening degree control is realized. Therefore, immediately after time t4, the response characteristic of P to I is linear. Similarly, when the change direction of the current I switches from decrease to increase, ΔIhys occurs in the direction in which I increases (see FIG. 3). In the present embodiment, when the change direction of Icmd switches from decrease to increase, Ioffset is superimposed on Icmd in a direction to increase the size of Icmd (a current command value Icmd obtained by adding positive Ioffset to the original Icmd) . Therefore, I is corrected to reduce ΔIhys. As described above, by adjusting Ioffset to Icmd in the direction in which ΔIhys decreases, ΔIhys is reduced, the control accuracy of the solenoid valve 24 is improved, and linear valve opening degree control becomes possible.

  Note that whether or not the change direction of the current I has been switched may be estimated based on the actual current Ireal. In the present embodiment, the change direction of the current I can be accurately estimated by making a determination based on the current command value Icmd. Also, the current reference response Iref_ofs, which is the reference of the current response of the solenoid, is calculated from the current command value Icmd, and based on the sign Idot / │Idot | of the differential value Idot of Iref_ofs, whether the current command value Icmd switches from increase to decrease To judge. Therefore, the change direction of the current I can be estimated more accurately, and chattering of the determination of the current change direction caused by the change of Icmd accompanying the change of the target pulley pressure P * can be prevented. Therefore, hysteresis difference ΔIhys can be reduced more effectively.

  In the region where the current command value Icmd is large, the magnitude of the offset signal Ioffset is made larger than in the region where Icmd is small. In other words, the hysteresis difference ΔIhys of the current I with respect to the valve opening degree is acquired in advance (see FIG. 3), and in the region of Icmd where ΔIhys is large, the magnitude of Ioffset is made larger than in the region of Icmd where ΔIhys is small. That is, in the region where I is large, ΔIhys is larger than in the region where I is small. With respect to such hysteresis characteristics, in the region where ΔIhys is large, ΔIhys can be more effectively reduced by increasing the magnitude of Ioffset. In this embodiment, the solenoid valve 24 is normally closed, P increases as I increases, and ΔIhys increases as P is higher (plunger movement amount is larger). The valve 24 may be normally open and P may decrease as I increases, or ΔIhys may increase as P is lower (the amount of movement of the plunger is larger). Also in this case, in the region where I is large, ΔIhys is larger than in the region where I is small.

  Further, in the region where the current command value Icmd is large, the change amount d Ioffset / d Icmd of the offset signal Ioffset with respect to the change of Icmd is made larger than in the region where Icmd is small. Specifically, in a region where Icmd is larger than Icmd1, d Ioffset / d Icmd is made larger than in a region where Icmd is smaller than Icmd1. That is, in the region where I is large, the amount of change dΔIhys / dI of ΔIhys with respect to the change of I is larger than in the region where I is small. With respect to such hysteresis characteristics, ΔIhys can be reduced more effectively by increasing dIoffset / dIcmd in a region where dΔIhys / dI is large.

  Not only the offset signal Ioffset but also the dither signal Idiz is superimposed on the current command value Icmd. Therefore, the influence of the hysteresis characteristic can be suppressed more effectively, the control of the solenoid valve 24 can be stabilized, and the control accuracy can be improved. Note that Idiz is not limited to a sine wave, and may be, for example, a pulse.

  In the region where the current command value Icmd is large, the amplitude Adiz of the dither signal Idiz is made larger than in the region where Icmd is small. That is, in the region where I is large, ΔIhys becomes larger than in the region where I is small (see FIG. 3). With respect to such hysteresis characteristics, by increasing Adiz in a region where ΔIhys is large, ΔIhys can be reduced more effectively. In other words, by approximately averaging the reduction effect of ΔIhys by Idiz (hereinafter referred to as hysteresis reduction effect) regardless of the control region of I, a good response of the valve opening degree to Icmd is maintained, and a solenoid valve By improving the control accuracy of 24, it becomes possible to perform linear valve opening control.

  Both the dither signal Idiz and the offset signal Ioffset are superimposed on the current command value Icmd. If the upper limit of the solenoid current I is limited by the maximum current Imax (determined by the product), a sufficient dither amplitude Adiz can not be set in a region where Icmd is large (close to Imax), and the hysteresis only in the dither signal Idiz There is a possibility that the difference ΔIhys can not be reduced sufficiently. On the other hand, in the present embodiment, by overlapping not only Idiz but also Ioffset, it is possible to reduce ΔIhys that can not be reduced by Idiz, so control accuracy can be further improved and linear valve opening control can be performed. It becomes. The details will be described below.

  FIG. 8 shows a time chart similar to FIG. 7 of a comparative example in which only the dither signal Idiz is superimposed on the current command value Icmd and the hysteresis difference ΔIhys is to be reduced only by the Idiz. From time t11 to time t13, Icmd is increased from 0 with a constant gradient. From time t13 to time t16, Icmd is decreased to 0 with a constant slope. When trying to reduce ΔIhys only with Idiz, it is necessary to set the amplitude Adiz of Idiz large in a region where ΔIhys is large in order to eliminate the influence of the hysteresis characteristic and perform linear valve opening control. Therefore, in the comparative example, Adiz is determined by the position of the plunger. For example, change Adiz according to Icmd, and increase Adiz as Icmd is larger. In FIG. 8, the distance between Icmd and the dashed line flanking Icmd indicates the Adiz needed to reduce ΔIhys. However, when the upper limit of the solenoid current I is limited by the current maximum value Imax, sufficient Adiz can not be set in a region where I is large. From time t12 to time t14 across time t13, Idiz saturates in the high current region (Icmd superimposed with Idiz interferes with Imax) due to the limitation of Imax, and a proper Adiz can not be obtained. For this reason, ΔIhys can not be sufficiently reduced, and linear valve opening control becomes difficult. From time t12 to time t14, the actual pulley pressure P does not follow the target pulley pressure P * (hydraulic response in the case of following Icmd) corresponding to Icmd. When the change direction of Icmd (P *) switches, a hysteresis characteristic appears and the hydraulic response stagnates (delays).

  On the other hand, in the present embodiment, as shown in FIG. 7, the hysteresis characteristic is corrected by superimposing Ioffset on Icmd when the change direction of Icmd is switched. Therefore, ΔIhys can be sufficiently reduced, control accuracy can be improved, and linear valve opening control can be performed. P follows P * corresponding to Icmd, and the current-pulley pressure characteristic is linear. Note that Adiz is set to the maximum value Adiz_max in a region where I cmd is large (region of I cmd 2 or more). Therefore, even if Icmd approaches Imax, saturation of Idiz is suppressed. That is, it is easy to avoid the situation where the hysteresis reduction effect by Idiz is hindered.

  The distribution of the magnitude of the offset signal Ioffset and the magnitude (amplitude Adiz) of the dither signal Idiz is preset, for example, as follows. That is, in the region where the current command value Icmd is small, the above allocation is set such that the reduction effect of ΔIhys by Idiz is larger than the reduction effect of ΔIhys by Ioffset, as compared with the region where Icmd is large. That is, the solenoid characteristics (current-pulley pressure characteristics as shown in FIG. 3, for example, the magnitude of ΔIhys) vary depending on the product. When correcting the hysteresis characteristics with two, Idiz and Ioffset, Idiz is not susceptible to variations in solenoid characteristics, but Ioffset is susceptible to variations in solenoid characteristics. Then, in the region where Icmd is small, the control accuracy of the valve opening degree (pulley pressure P) is required to be higher than in the region where Icmd is large. Also, in the region where Icmd is small, there is almost no limit (by Imax) to the amplitude Adiz of Idiz. Therefore, in a region where Icmd is small, the distribution of the magnitudes of both signals is set so that the hysteresis reduction effect by Idiz becomes larger than the hysteresis reduction effect by Ioffset. Thereby, it is possible to reduce ΔIhys with high accuracy while avoiding the influence of the variation of the solenoid characteristic. When Ioffset is set in advance in the map of FIG. 5, it is preferable to set Ioffset so as to correct the above-mentioned variation of the solenoid characteristic (size of ΔIhys). In addition, in a region where Icmd is small, only Idiz may be used and Ioffset may not be used.

  On the other hand, in the region where Icmd is large, higher control accuracy is not required than in the region where Icmd is small. Also, in the high current region near Imax, a limitation may be imposed on the amplitude Adiz of Idiz. Therefore, in the region where Icmd is large, the distribution of the magnitudes of both signals is set so that the hysteresis reduction effect by Ioffset becomes larger than the hysteresis reduction effect by Idiz. This makes it possible to accurately reduce ΔIhys despite the above restriction on Adiz. In a region where I cmd is large (in particular, around I max), only I offset may be used and Idiz may not be used.

  Specifically, in the region where the current command value Icmd is large, the change amount d Ioffset / d Icmd of the offset signal Ioffset with respect to the change of Icmd is made larger than in the region where Icmd is small. Thus, it is easy to make the hysteresis reduction effect by Ioffset greater than the hysteresis reduction effect by the dither signal Idiz in a region where Icmd is large. In other words, in the region where Icmd is small, dIoffset / dIcmd_x is smaller than in the region where Icmd is large. Thus, in a region where Icmd is small, it is easy to make the hysteresis reduction effect by Idiz larger than the hysteresis reduction effect by Ioffset.

[effect]
The effects of the present embodiment will be listed below.
(1) The current control method includes the step of superimposing the dither signal Idiz on the current command value Icmd of the proportional solenoid that drives the solenoid valve 24, and the offset signal whose magnitude is larger in the region where Icmd is larger than in the region where Icmd is small. It has the steps of superposing Ioffset on Icmd, and controlling the current I of the proportional solenoid so as to realize a hysteresis correction current command value Icmd_hys which is Icmd in which Idiz and Ioffset are superimposed.
Therefore, the hysteresis difference ΔIhys can be effectively reduced by superimposing both Idiz and Ioffset on Icmd, and the control accuracy of the solenoid valve 24 can be improved. Also, in contrast to the hysteresis characteristics where ΔIhys is larger in the region where I is larger than in the region where I is smaller, ΔIhys is made more effective by increasing the size of Ioffset in the region where Icmd is larger than in the region where Icmd is small. It can be reduced.

(2) A CVT control unit 1 (current control device) for controlling the current I of the proportional solenoid to control the opening degree of the solenoid valve 24 driven by the proportional solenoid, which corresponds to the current command value Icmd of the proportional solenoid A dither signal operation unit 116 for overlapping the dither signal Idiz and a current command value operation unit for hysteresis correction 117 (dither signal overlapping unit), an offset signal operation unit 114 for superimposing the offset signal Ioffset on Icmd, and a current command value for hysteresis correction The arithmetic unit 117 (offset signal superposition unit), and a current control unit 10 that controls the current I of the proportional solenoid so as to realize a hysteresis correction current command value Icmd_hys that is Icmd on which Idiz and Ioffset are superimposed, The offset signal superposition unit makes the magnitude of Ioffset larger in the region where Icmd is larger than in the region where Icmd is small.
Therefore, the same effect as the above (1) can be obtained.

(3) The offset signal operation unit 114 (offset signal superposition unit) makes the change amount d Ioffset / d Icmd of the offset signal Ioffset with respect to the change of Icmd larger than in the region where Icmd is small in the region where the current command value Icmd is large. .
Therefore, in the region where I is large, ΔIhys can be more effectively reduced with respect to the hysteresis characteristic in which the change amount dΔIhys / dI of the hysteresis difference ΔIhys with respect to the change of I is larger than in the region where I is small. In addition, in the region where Icmd is large, it is easy to make the hysteresis reduction effect by Ioffset greater than the hysteresis reduction effect by the dither signal Idiz, whereby the control accuracy of the solenoid valve 24 can be improved.

(4) The offset signal calculation unit 114 (offset signal superposition unit) acquires in advance the hysteresis difference ΔIhys of the current I with respect to the opening degree of the solenoid valve 24, and in the region of the current command value Icmd with large ΔIhys, The magnitude of the offset signal Ioffset is made larger than in the region.
Therefore, ΔIhys can be reduced more effectively by increasing the magnitude of Ioffset in a region where the hysteresis difference ΔIhys is large in accordance with the hysteresis characteristics acquired in advance.

(5) Offset signal calculation unit 114 and hysteresis correction current command value calculation unit 117 (offset signal superposition unit) change the direction of change of current command value Icmd so that the hysteresis difference ΔIhys of current I relative to the opening degree of solenoid valve 24 The offset signal Ioffset is superimposed on Icmd in the direction of decreasing.
As described above, since Icmd is corrected so as to reduce the hysteresis difference ΔIhys generated when switching the change direction of the current I, ΔIhys can be reduced.

(6) The offset signal calculation unit 114 (offset signal superposition unit) calculates the current reference response Iref_ofs, which is the reference of the current response of the proportional solenoid, from the current command value Icmd, and the sign Idot / | Idot | Based on the change direction of Icmd.
Therefore, the change direction of the current I can be accurately estimated, and the hysteresis difference ΔIhys can be reduced more effectively.

(7) A hydraulic control device for a continuously variable transmission 7 (automatic transmission) for a vehicle including a CVT control unit 1 (current control device), wherein the solenoid valve 24 is a pulley for operating the continuously variable transmission 7 Control the pressure P.
Therefore, the accuracy of control of the pulley pressure P (gear ratio control) can be improved.

[Other embodiments]
As mentioned above, although the form for implementing this invention was demonstrated based on drawing, the specific structure of this invention is not limited to the said embodiment, The design change of the range which does not deviate from the summary of invention etc. Are included in the present invention. For example, the automatic transmission is not limited to the continuously variable transmission, and may be, for example, a stepped transmission.

1 CVT control unit (current controller)
10 Current control unit (control unit)
116 Dither signal operation unit (Dither signal superposition unit)
117 Hysteresis correction current command value calculation unit (dither signal superposition unit)
114 Offset signal operation unit (Offset signal superposition unit)
117 Hysteresis correction current command value calculation unit (offset signal superposition unit)
24 Solenoid valve 7 Continuously variable transmission mechanism (automatic transmission)

Claims (6)

Superimposing a dither signal on a current command value of a proportional solenoid that drives the valve;
The current command value is a large area rather large in size than the current command value is small regions, wherein the current command value is larger area than the current command value is small, the change amount with respect to a change in the current command value a step is overlapped with respect to the current command value offset signal has magnitude,
And a step of controlling the current of the proportional solenoid so as to realize the dither signal and the current command value which the offset signal is superimposed,
Current control method. A current control device for controlling the current of the proportional solenoid to control the opening degree of a valve driven by the proportional solenoid,
A dither signal superposition unit which superimposes a dither signal on the current command value of the proportional solenoid;
An offset signal superposition unit which superimposes an offset signal on the current command value;
And a control unit for controlling the current of the proportional solenoid so as to realize the dither signal and the current command value which the offset signal is superimposed,
The offset signal superimposing unit makes the magnitude of the offset signal larger in a region where the current command value is larger than in a region where the current command value is small, and the current command value is small in a region where the current command value is large. The amount of change of the offset signal with respect to the change of the current command value is made larger than that of the region
A current control device characterized by In the current control device according to claim 2,
The offset signal superposition unit obtains in advance the hysteresis difference of the current with respect to the opening degree of the valve, and in the region of the current command value where the hysteresis difference is large, than in the region of the current command value where the hysteresis difference is small. Increase the magnitude of the offset signal ,
A current control device characterized by The current control device according to any one of claims 2 to 3.
The offset signal superimposing unit, the change direction of the current command value is switched, the direction in which the hysteresis difference decreases the current to the opening of the valve, overlaps the offset signal to the current command value,
A current control device characterized by In the current control device according to claim 4 ,
The offset signal superimposing unit calculates a current reference response that is a reference of current response of the proportional solenoid from the current command value, and determines a change direction of the current command value based on a sign of a differential value of the current reference response. Do ,
A current control device characterized by A hydraulic control device for an automatic transmission for a vehicle, comprising the current control device according to any one of claims 2 to 5,
The valve controls the hydraulic pressure that operates the automatic transmission .
A hydraulic control device for an automatic transmission characterized in that .

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