JPH03181659A - Controller for continuously variable transmission - Google Patents

Abstract

PURPOSE:To improve the responsiveness of a controller by obtaining primary pressure required for maintaining fixed transmission for fixed input torque to secondary pressure, and adding or subtracting pressure necessary for an oil pressure ratio and a flow rate control system into or from the above primary pressure to determine target primary pressure. CONSTITUTION:A computing section 88 computes necessary primary pressure corresponding to an input torque ratio KT in the normal case and a speed change ratio (i) to secondary pressure established by a setting section 80, and a primary control valve is controlled on the primary pressure computed by the computing section 88 through a target primary pressure computing section 95, a solenoid current setting section 96 and proportional solenoid 61 to maintain each speed change ratio on the above oil pressure ratio. On the other hand, at transient time, a speed change pressure computing section 94 for a flow rate control system computes pressure Pp required for producing speed change speed de/dt, and the computing section 95 adds or subtracts the pressure Pp into or from a pressure ratio control system to increase or decrease the target primary pressure, and the primary control valve increases the primary pressure for upshifting and decreases it for downshifting. Thus feed forward controllability can be improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control device that electronically controls primary pressure and secondary pressure in a belt-type continuously variable transmission for a vehicle. Related to electronic control systems using control valves and primary control valves.

[Conventional technology]

This type of continuously variable transmission applies a primary pressure to a primary brake at the input end, and a secondary pressure to a secondary brake at the output side to apply a pressing force to the belt wrapped around both pulleys. The secondary pressure is controlled to provide a pressing force that does not cause belt slip to the transmitted torque, and the primary pressure can shift the belt to the primary or secondary boost to obtain a predetermined gear ratio. Controlled to the possible pressing force.

Generally, there is a tendency for the secondary pressure and primary pressure control valves and control systems to be computerized. The system accurately determines the transmission torque of the pulley and belt, and optimally controls the secondary pressure to the necessary minimum level according to the transmission torque. Regarding the primary pressure, 0 refers to determining the optimum shift state depending on driving and driving conditions and controlling the shift with good response.

Conventionally, regarding electronic control of the above-mentioned continuously variable transmission, there is a prior art, for example, disclosed in Japanese Patent Application Laid-Open No. 63-303258. Here, especially regarding speed change control, flow rate control will be introduced as a basic concept of control. In other words, the amount of oil that determines the primary pressure in the primary cylinder can be set as a function of the gear ratio, and the flow rate obtained by differentiating the oil amount with time is a function of the gear speed and gear ratio, so the four-standard gear ratio can be set according to each condition. The shift speed is calculated based on the deviation between the actual gear ratio and the actual gear ratio. In addition, the flow rate at the control valve is calculated from the opening area, pressure difference, etc., and if the manipulated variable is determined by a predetermined duty ratio, the duty ratio becomes a function of the gear speed and gear ratio, and the duty ratio is determined based on this. stipulate. It is shown that a duty signal is output to the solenoid valve to generate a pulse-like control pressure, and this control pressure is applied to the control valve to control the flow rate, thereby controlling the speed change.

[Problem to be solved by the invention]

By the way, the above-mentioned prior art is a control method that emphasizes tracking the actual gear ratio with respect to the target gear ratio by controlling the flow rate of the control valve, and is excellent in moment-to-moment gear change controllability. However, due to the emphasis on followability, hunting may occur due to lack of convergence depending on the magnitude of the manipulated variable, and there is a limit to responsiveness during transient times. In addition, the gear ratio is originally determined by two hydraulic pressures, the secondary pressure and the primary pressure, but because this relationship is not incorporated into the control, there is no standard parameter in steady state, and when performing feedforward control. difficult. Furthermore, when an abnormality such as a wheel lock occurs, it becomes impossible to detect the gear ratio, and there is a problem that the gear ratio cannot be controlled to an optimum gear ratio.

The present invention has been made in view of these points, and its purpose is to easily and improve shift controllability by also adopting hydraulic ratio control between secondary pressure and primary pressure, and to easily improve speed change control even in abnormal situations. An object of the present invention is to provide a control device for a continuously variable transmission that can handle the above problems.

[Means to solve the problem]

In order to achieve the above object, the control device for a continuously variable transmission of the present invention regulates the pump discharge pressure with a secondary control valve to control the secondary pressure of the secondary cylinder, and reduces the secondary pressure with the primary control valve to control the secondary pressure of the secondary cylinder. In a control system that changes speed by controlling the primary pressure of a cylinder, the electromagnetic control system of the primary control valve includes a hydraulic ratio control system and a flow rate control system, and the hydraulic ratio control system is configured to control a predetermined input torque. The primary pressure necessary to maintain a predetermined gear ratio is determined from the secondary pressure, and the flow control system determines the pressure necessary to achieve a predetermined gear change speed, and the hydraulic ratio control system and the flow control system A target primary pressure is determined by adding and subtracting the required pressure, and an electric signal corresponding to this target primary pressure is output to the primary control valve.

[For production]

Based on the above configuration, in the hydraulic ratio control system of the electronic control system, the required primary pressure according to the steady state input torque and gear ratio is calculated for the secondary pressure, and the electric signal of the target primary pressure corresponding to this is used for primary control. The primary pressure is now controlled by manual input to the valves, and in steady state, each gear ratio is controlled to be maintained at the hydraulic ratio. In addition, during transient periods, the flow rate control system calculates the pressure required to achieve the shifting speed, and this is added to or subtracted from the hydraulic ratio control system to increase or decrease the target primary pressure, and the primary control valve increases the primary pressure. The gear shift is now controlled to shift, reduce and downshift.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Referring to FIG. 1, an outline of the drive system of a continuously variable transmission with a lock-up converter will be described. Reference numeral 1 is an engine, and a crankshaft 2 is connected to a torque converter device 31, a forward/reverse switching device 4. Continuously variable transmission 5 and differential device B
The transmission is configured sequentially.

In the torque converter device 3, the crankshaft 2 is connected to a converter cover 11 and a pump impeller 12a of a torque converter 12 via a drive plate 10. A turbine runner 12b of the torque converter 12 is connected to a turbine shaft 13, and a stator 12c is guided by a one-way clutch 14. The lock-up clutch 15, which is integral with the turbine runner 12b, is installed so as to be engageable or disengageable with the drive plate lO, and transfers the engine power to the torque converter 12 or the lock-up clutch 15.
communicate through.

The forward/reverse switching device 4 has a double pinion planetary gear 16, a turbine shaft 18 is input to the sun gear lea, and output is output from the carrier 18b to the primary shaft 2o. A forward clutch 17 is provided between the sun gear lea and the ring gear 16c, a reverse brake 18 is provided between the ring gear lee and the case, and engagement of the forward clutch 17 integrates the planetary gear I6 to connect the turbine shaft 13 and the primary shaft. 20 is directly connected. Further, by engaging the reverse brake 18, reversed power is output to the primary shaft 20, and by releasing the forward clutch 17 and reverse brake 18, the planetary gear 16 is made free.

The continuously variable transmission 5 has a hydraulic cylinder 2I on the primary shaft 20.
The variable-boot interval primary pulley 22 has
A secondary pulley 25 having a hydraulic cylinder 24 is similarly provided on the secondary shaft 23, and the primary pulley 2
A drive belt 2B is wound between the drive belt 2 and the secondary pulley 25. Here, the pressure-receiving area of the primary cylinder 21 is set to be larger than that of the primary cylinder 21, and the primary pressure of the primary cylinder 21 causes the primary pulley 22. The winding around the secondary pulley 25 is configured to change the diameter ratio so as to be continuously variable.

In the differential device 6, an output shaft 28 is connected to a secondary shaft 23 via a pair of compression gears 27.
The drive gear 29 of this output shaft 28 is the final gear 3.
meshes with 0. And the differential device 31 of the final gear 30
are connected to left and right wheels 33 via a vehicle 32.

On the other hand, in order to obtain a hydraulic pressure source for controlling the continuously variable transmission, a main oil pump 34 is disposed adjacent to the torque converter i2, and this main oil pump 34 is connected to the converter cover ll by a pump drive shaft 35, and is always connected to the converter cover ll. The pump is driven by engine power to generate hydraulic pressure. In the continuously variable transmission 4, since the oil pressure is controlled over a wide range of high and low levels, the oil pump 34 is, for example, of a roller vane type and has a plurality of sets of suction and discharge boats, and is configured as a variable displacement type.

Next, a continuously variable transmission control system will be described as a hydraulic control system.

First, an oil passage 41 from the oil pump 34 that communicates with the oil pan 40 communicates with the secondary control valve 50 to generate a predetermined secondary pressure Ps, and this secondary pressure Ps is constantly supplied to the secondary cylinder 24 through the oil passage 42. be done. The secondary pressure Ps is guided to the primary control valve BO via the oil passage 43, and is configured to be supplied to and discharged from the primary cylinder 21 through the oil passage 44 to generate the primary pressure Pp.

The secondary control valve 50 is a proportional electromagnetic relief valve type, and a solenoid current Is is supplied to the proportional solenoid 51 by the control unit 7o. Then, the solenoid current I
s causes the electromagnetic force, the hydraulic reaction force of the secondary pressure Ps, and the spring force to act on the spool in opposition, and the pressures are adjusted so that these are balanced. That is, solenoid current 1s
The set pressure is made variable by 1 for the solenoid current Is.
The secondary pressure Ps is controlled in a proportional relationship of one to one.

The primary control valve 60 is a proportional electromagnetic pressure reducing valve type, and like the secondary control valve 50, the solenoid current 1p is supplied to the proportional solenoid 61 by the control unit 70.

Then, the electromagnetic force caused by the solenoid current 1p, the hydraulic reaction force of the primary pressure Pp, and the spring force act on the spool in opposition, and the set pressure is made variable by the solenoid current 1p, so that it is proportional to the solenoid current 1p in a 1:1 ratio. The primary pressure Pp is controlled based on this relationship.

Note that the oil pump 34 is of a variable displacement type, and a relatively high lubricating pressure is always generated in the oil passage 45 on the drain side of the secondary control valve 50. Therefore, this lubricating pressure is applied to the torque converter 12. Forward/forward switching device 4. The circuit is configured so that the lubricant is supplied to the lubricating section of the belt 24, etc.

In FIG. 2, the electronic control system will be described.

First, a primary pulley rotation speed sensor 71. is used as a human power signal sensor. Secondary boolean speed sensor 72, engine speed sensor 73. It has a throttle opening sensor 74 and a pressure sensor 75 that detects a secondary pressure Ps.

Regarding the secondary pressure control system, it has an engine torque calculation unit 76 that manually calculates the throttle opening θ of the throttle opening sensor 74 and the engine rotation speed Ne of the engine rotation speed sensor 73, and calculates the engine torque based on the torque characteristic of θ-No. Estimate Te. In addition, the torque converter, output side engine rotation speed No., and brake rotation speed N
p is input manually to the torque amplification factor calculation unit 77, and the speed ratio n (N
The torque amplification factor t is determined according to fl/Ne). Furthermore,
The engine rotation speed Ne and the primary pulley rotation speed Np are manually input to the primary system inertia force calculation unit 78, and the inertia force g is calculated based on the mass and acceleration of the engine l and the primary pulley 22.
! Calculate. These engine torques Te.

The torque amplification factor t and the inertial force gl are input to the human torque calculation section 79, and the CVT input torque TI is calculated as follows.

TI -Te-t-gl On the other hand, the necessary secondary pressure setting section 8 where the actual gear ratio i is manually operated
has 0. Here, the secondary pressure Psu at the slip limit required for unit torque transmission for each actual gear ratio I is shown in Figure 3 (
The map is set as shown in a), and the required secondary pressure Psu is determined according to the actual gear ratio l using this map. And the above input torque TI.

The required secondary pressure Psu is determined by the target secondary pressure calculation unit 81.
These human torque TI, required secondary pressure P
Based on su and the secondary pulley rotation speed Ns, the target secondary pressure Pss is calculated as follows, taking into account the centrifugal oil pressure gs of the secondary cylinder 24 portion.

Pss-Tl ・Psu-gs +PM where 4%4
is a correction term expressed as PM-f(+) as a function of the actual speed ratio I, and is called a margin.

The target secondary pressure Pss is further determined by the solenoid current setting section 8.
2, the solenoid current Is is determined according to the target secondary pressure Pss. In this case, since the secondary control valve 50 has a characteristic of controlling the secondary pressure in a proportional relationship to the solenoid current Is, as described above,
The solenoid current Is with respect to the target secondary pressure Pss is determined proportionally using the map shown in FIG. 3(b) corresponding to this. This solenoid current Is is then supplied to the proportional solenoid 5I of the secondary control valve 50 via the drive unit 83, and in this way, the solenoid current Is causes
The secondary pressure Ps is directly controlled to follow the target secondary pressure Pss.

Next, the primary pressure control system will be described.

First, to explain the basic concept of control, the actual gear ratio I in steady state is determined by the hydraulic ratio between the secondary pressure Ps and the primary pressure Pp, so the hydraulic ratio Kp (Pp/Ps) can be expressed as a function of the actual gear ratio i. This results in Kp −r(1).

On the other hand, in the boob and belt part, the human torque T
For example, when I becomes large, the gear shifts to a downshift direction, and it can be seen that the human torque TI influences the actual gear ratio 1. Therefore, for the relationship between this human power torque TI and the actual gear ratio I, the maximum torque (Ps/P su) that can be transmitted with the current secondary pressure Ps and the torque ratio KT of the input torque TI of the current transmitted torque are determined by K. Set by T - T I/ (Ps/Psu). Then, the current torque transmission state.

That is, the actual gear ratio l is determined in relation to the oil pressure ratio Kp, and as a result, the oil pressure ratio Kp is expressed as Kp -1'(1, KT) as a function of the actual gear ratio and the torque ratio. In this way, the hydraulic ratio Kp can be obtained with similar characteristics regardless of the secondary pressure Ps, as shown in FIG. 3(C), based on the actual gear ratio 1 and the torque ratio Kr.
The required primary pressure PPD is calculated from this oil pressure ratio Kp and the secondary pressure Ps.

Thereby, the primary pressure PPD required to maintain the current actual gear ratio I with respect to the current manual torque T1 in a steady state can be determined with respect to the secondary pressure Ps.

Next, the speed change control during the transient period may be performed by controlling the flow rate according to the desired speed change speed. Therefore, the speed change speed or If the pulley position is set, calculate the pulley position change speed de/dt. Here, since the pulley position change rate de/dt is the volume change of the primary cylinder 21, that is, the flow rate, the opening area, that is, the valve displacement is determined using the pulp flow rate formula, and the pulley position change rate de/dt is determined accordingly. Convert to the pressure ΔPp required to achieve this.

Then, the required primary pressure PP obtained by the above-mentioned hydraulic ratio control
By adding or subtracting the pressure ΔPp to D according to upshifts and downshifts, the target primary pressure Pps can be found.

Therefore, based on such control, a hydraulic ratio control system and a flow rate control system are provided.

Regarding the hydraulic ratio control system, the primary pulley rotation speed Np of the primary pulley rotation speed sensor 71 and the secondary pulley rotation speed N of the secondary pulley rotation speed sensor 72
It has an actual speed ratio calculating section 85 to which s is input, and calculates the actual speed ratio I by 1-Np/Ns. On the other hand, input torque TI
, the required secondary pressure Psu and the secondary pressure Ps of the pressure sensor 75 are manually operated by a torque ratio calculating section 8B, which calculates the torque ratio Kr. Figure 3 (C)
The hydraulic ratio Kp is determined from the relationship between the torque ratio KT and the actual gear ratio I using the map. Hydraulic ratio Kp, secondary pressure Ps
is manually inputted to the required primary pressure calculation unit 88, and the required primary pressure PPD is calculated by taking into account the centrifugal oil pressure gp of the primary cylinder 21 portion due to the primary pulley rotation speed Np.
is calculated as follows.

PPD-Kp -Ps -gp Next, referring to the flow rate control system, it has a target primary boost rotation speed retrieval unit 89 that manually determines the actual gear ratio l and throttle opening θ, and determines the target primary boost rotation speed based on the relationship ■-θ. Determine the rotation speed NPD. The target primary pulley rotation speed N PD and the secondary pulley rotation speed Ns are input to the target gear ratio calculating section 90, and the target gear ratio is is calculated as 1s-NPD/N.
In this way, the target gear ratio 1 is calculated according to each driving and driving condition based on the gear shift pattern.
s is required.

Here, the oil amount V of the primary cylinder 21 is proportional to the actual boob position e, and the flow rate Q obtained by time-differentiating the oil amount V has a one-to-one correspondence with the boob position change rate de/dt. Therefore, since it is preferable that the flow rate Q is directly calculated based on the boolean position change rate de/dt, the actual gear ratio I and the target gear ratio 1
s is the actual pulley position converter 91° target pulley position converter 9
2, the actual pulley position e.

Convert to target pulley position es. These real pulley positions e
, the target boolean position as is calculated by the boolean position change speed calculation unit 93.
is input, and the boom position change rate de/dt is calculated from the deviation between the actual pulley position e and the target boom position es, etc., as shown below.

de/dt -, ・(as-e)・K2・des
/di (K+, 2: constant, des/di: phase advance element) and the pulley position change rate de/dt are input manually to the shift pressure calculation unit 94, and the pulley position change rate de/d
The pressure ΔPp required for shifting is determined based on the flow rate due to t.

In this way, the required primary pressure PPD of the hydraulic ratio control system and the shift pressure ΔPp of the flow rate control system are input to the standard primary pressure calculation unit 95, and the 4-standard primary pressure Pps is calculated by Pps - PPD + ΔPp at the time of upshift. When downshifting, it is calculated by Pps-PPD-ΔPp. The target primary pressure Pps is further determined by the solenoid current setting section 96.
The solenoid current 1p is determined manually according to the target primary pressure Pps. In this case, the primary control valve 6
0 has the characteristic of controlling the primary pressure proportionally to the solenoid current ip, so the solenoid current 1p for the target primary pressure Pps is determined using the map shown in FIG. 3(b) corresponding to this characteristic. This solenoid current 1p is then supplied to the proportional solenoid 6I of the primary control valve BO via the drive section 97, so as to perform feedforward speed change control.

Next, the operation of the continuously variable transmission control device having such a configuration will be described.

First, by operating engine I, torque converter 12
converter cover 11. The oil pump 34 is driven by the rear drive shaft 35 to generate oil pressure, and this oil pressure is guided to the secondary control valve 5o. Therefore, when stopped, the target gear ratio ls of the primary control system.

The actual speed ratio I is set as the mechanically maximum speed ratio of the continuously variable transmission 5 to a value larger than 2.5, for example. Therefore, the actual gear ratio of the hydraulic control system is 1. Torque ratio KT.

The target primary pressure Pps based on the extraction pressure ratio Kp and the secondary pressure Ps flows into the proportional solenoid 61 of the primary control valve 8o and operates toward the oil drain side, so that the primary pressure Pp becomes the lowest level. Therefore, all of the secondary pressure Ps generated by the secondary control valve 50 is transferred to the secondary cylinder 24.
The continuously variable transmission 5 is in a low speed gear with the maximum gear ratio in which the belt 2B is shifted furthest toward the secondary pulley 25.

At this time, the lock-up clutch 15 is released by a hydraulic control system (not shown), and the torque converter 12 is supplied with oil. Therefore, for example, when shifting to the drive range, the forward clutch 17 of the forward/reverse switching device 4 is engaged by refueling and becomes the forward position.

Therefore, the power of the engine I is transferred to the torque converter 12,
It is input to the primary shaft 20 of the continuously variable transmission 5 via the forward/reverse switching device 4, and the primary pulley 22. The power of the maximum gear ratio is outputted to the secondary shaft 23 by the secondary pulley 25 and the belt 26, which is transmitted to the differential device 6.
The signal is transmitted to the wheels 33 via , and the vehicle can be started.

In the secondary pressure control system, the engine torque TO is always estimated, and the torque amplification factor t and the inertia force gt of the primary system are calculated. Therefore, when the vehicle starts moving by pressing the accelerator, the input torque TI increases due to the engine torque Te and the torque amplification factor t, and the required secondary pressure Psu also increases, so that the target secondary pressure Pss becomes a large value. A low solenoid current Is corresponding to the target secondary pressure Pss flows to the proportional solenoid 51 of the secondary control valve 50 to set the set pressure high, and thus the secondary pressure Ps is controlled to be high by reducing the drain amount.

Then, after starting, the gear shift is controlled and the lock-up clutch 1
5 is engaged and the torque amplification factor becomes t-1, the necessary secondary pressure Psu is reduced according to the actual gear ratio i, and when the engine torque Te is lowered as the vehicle speed increases, the target secondary pressure Pss suddenly becomes becomes smaller. Therefore, the solenoid current Is increases rapidly, the set pressure of the secondary control valve 50 gradually decreases, and the secondary pressure Ps is controlled to decrease. In this way, the characteristics of Ps are summarized as shown in FIG. 4(a), and optimal control is always performed to ensure the minimum pulley pressing force that does not cause belt slip with respect to the transmitted torque.

The secondary pressure Ps is guided to the primary control valve 60, and the primary pressure Ps is applied to the primary cylinder 21 by a pressure reducing action.
P is generated, and the speed change is controlled by this primary pressure Pp, which will be described below.

First, when the vehicle starts moving at the maximum gear ratio, the primary control valve 60 exerts the greatest pressure reducing effect by the hydraulic ratio control system, and maintains the primary pressure Pp at the lowest level. And depending on driving and driving conditions! The shift start condition of s<2.5 is satisfied,
When the target gear ratio Is is successively set smaller, the flow rate control system calculates the boolean position change rate de/dt, and accordingly the gear shift pressure ΔPp is generated to increase the target primary pressure Pps. Therefore, the solenoid current Ip is gradually decreased, and the set pressure is increased by the electromagnetic force of the proportional solenoid 61 in the primary control valve 60, and the primary pressure Pp is controlled to be higher sequentially. The belt 26 then moves toward the primary pulley 22 and upshifts to a high speed gear with a small gear ratio.

Further, when the actual speed ratio l becomes smaller due to the speed change control, the oil pressure ratio Kp is set to be increased in the oil pressure ratio setting section 87 of the oil pressure ratio control system, and the ratio of the required primary pressure PPD to the secondary pressure Ps is increased. Then, the target primary pressure Pps is increased by the primary pressure PPD, and the level of the primary pressure Pp is increased and maintained.In this way, each time the actual gear ratio I becomes smaller due to an upshift, the actual gear ratio l is maintained by the hydraulic ratio control system. The primary pressure Pp is sequentially controlled to increase to such a level. Further, when the human power torque TI increases, for example, the torque ratio KT becomes a large value in the torque ratio calculating section 86, and thereby the value of the oil pressure ratio Kp also increases. Therefore, the primary pressure Pp is corrected to increase so as to prevent the downshift tendency due to the increase in the human torque TI.

Then, the target gear ratio is is the minimum gear ratio 1+ (for example, 0
．． 5> and the target primary pressure Pps is set to the highest level, the solenoid current 1p becomes the smallest and the set pressure of the primary control valve 6o is maximized.
The primary pressure Pp is controlled to the highest level. At this time, when the actual gear ratio I also follows the target gear ratio ls and reaches the minimum gear ratio ill, the target primary pressure Pps is set to the highest level by the oil pressure ratio Kp of the hydraulic ratio control system and the required primary pressure PPD. Therefore, the primary pressure Pp is maintained at a high state to maintain the minimum gear ratio I■.

On the other hand, when the accelerator is depressed and the vehicle speed decreases, the target gear ratio Is
When the value of ΔPp increases, the target primary pressure Pps becomes a low level by subtracting the shift pressure ΔPp. Therefore, the solenoid current 1p increases and the primary control valve 6
At 0, the primary pressure Pp is controlled to a low level due to pressure reduction, and as a result, the belt 26 moves toward the secondary pulley 25 again and downshifts. In the case of this downshift as well, as the actual gear ratio I increases, the target primary pressure Pps is reduced by the oil pressure ratio Kp and the required primary pressure PPD in the hydraulic ratio control system to the level necessary to maintain the actual gear ratio I. The primary pressure Pp is sequentially controlled to decrease.

In this way, the primary pressure pp is made variable by the hydraulic ratio control system and the flow rate control system over the range of the maximum speed ratio fL+minimum speed ratio iii as shown in FIG. It is controlled.

Although the embodiments of the present invention have been described above, the secondary pressure may be feedback-controlled using the deviation between the target secondary pressure and the secondary pressure. Furthermore, in the flow control system, the shift pressure may be determined using the shift speed. Further, the secondary control valve and the primary control valve may be either proportional electromagnetic type.

〔Effect of the invention〕

As described above, according to the present invention, in the shift control of a continuously variable transmission, the hydraulic ratio control system sets the primary pressure and shifts the gear, so hunting of the gear ratio is eliminated and responsiveness is improved. feedforward controllability is greatly improved.

Furthermore, in the hydraulic ratio control system, the hydraulic ratio can be accurately and stably determined for each gear ratio by taking into account the influence of human torque on gear shifting. Further, the necessary primary pressure can be easily and appropriately calculated from the oil pressure ratio and the secondary pressure.

Furthermore, the target primary pressure can be easily calculated by adding and subtracting the pressure for hydraulic ratio control and the shift pressure, and the control is also simplified.

Furthermore, by using a hydraulic ratio control system as a base, there are parameters that can be used as standards, making control easier.

Further, even in the event of an abnormality such as a wheel lock, the gear ratio can be maintained at an appropriate speed ratio, and belt slip due to sudden oil pressure fluctuations can be prevented.

Furthermore, since the secondary control valve and the primary control valve are of a proportional type, the solenoid current and oil pressure correspond one to one, facilitating control.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram showing an embodiment of a control device for a continuously variable transmission of the present invention, Fig. 2 is a block diagram of an electronic control system, and Fig. 3 (a) to C) are diagrams showing each map. , FIG. 4(a) is a diagram showing the secondary characteristic, and FIG. 4(b) is a diagram showing the shift pattern of the primary pressure. 5...Continuously variable transmission, 21...Primary cylinder,
24... Secondary cylinder, 50... Secondary control valve, 51, 61... Proportional solenoid, 60...
Primary control valve, 70... Control unit, 8B...
・Torque ratio calculation unit, 87...Poll pressure ratio setting unit, 88...
- Required primary pressure calculation unit, 93...Pulley position change speed calculation unit, 95...Target primary pressure calculation unit, 9B
...Solenoid current setting part 31Z3 (b) 7'3C

Claims (4)

[Claims] (1) In a control system in which the pump discharge pressure is regulated by a secondary control valve to control the secondary pressure of the secondary cylinder, and the secondary pressure is reduced by the primary control valve to control the primary pressure of the primary cylinder to change speed, The electromagnetic control system of the control valve includes a hydraulic ratio control system and a flow rate control system, and the hydraulic ratio control system converts the primary pressure necessary to maintain a predetermined gear ratio for a predetermined input torque into a secondary pressure. The flow control system calculates the pressure necessary to achieve a predetermined speed change speed, adds and subtracts the necessary pressures of the hydraulic ratio control system and flow control system to determine the target primary pressure, and determines the target primary pressure. A control device for a continuously variable transmission characterized by outputting an electric signal according to a primary pressure to a primary control valve. (2) The hydraulic ratio control system calculates the torque ratio from the secondary pressure, the pressure required for unit torque transmission for each gear ratio, and input torque, and adjusts the hydraulic ratio between the primary pressure and the secondary pressure based on the above torque ratio and gear ratio. The control device for a continuously variable transmission according to claim 1, wherein the required primary pressure is determined based on the hydraulic pressure ratio and the secondary pressure. (3) A claim characterized in that the flow rate control system calculates a gear shift speed based on the deviation between a target value and an actual value of a gear ratio, etc., and determines the pressure necessary for gear shifting at a flow rate corresponding to the gear shift speed. (1) A control device for a continuously variable transmission as described in (1). (4) Claim (1) characterized in that one or both of the secondary control valve and the primary control valve is a proportional solenoid type, and the solenoid current is proportionally determined and output according to the target secondary pressure or the target primary pressure. ) Control device for the continuously variable transmission.