JPH03189470A - Control device for continuously variable transmission - Google Patents

Abstract

PURPOSE:To absorb/ease fluctuation of engine speed so as to improve running performance by enlarging a fluid coupling operating region in lockup control by a region map in case of engine output at the time of low temperature is low and unstable. CONSTITUTION:Upon judging the low and unstable state of engine output by an engine output judging part 107 at the time of low temperature detected by a water temperature sensor 106, a control unit 80, switches a change-over part 109 from a lockup determining part 95 to the low-temperature lockup determining part 108 side so as to enlarge a fluid coupling operating region in lockup control by a region map. Fluctuation of engine speed is thereby absorbed/eased by the fluid coupling, and driving force at the time of up-shift is secured to improve running performance and also reduce vibrational noise.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a continuously variable transmission equipped with a combination of a lock-up fluid coupling and a belt-type continuously variable transmission in the drive system of a vehicle such as an automobile. The present invention relates to a control device, and more specifically, mainly relates to control of expanding a fluid coupling operating range during cold driving.

[Conventional technology]

In general, in a drive system that uses a torque converter with lockup, if the torque amplification effect of the torque converter is used at the time of starting, the starting performance will be strengthened and smoothness will be improved. Furthermore, after the vehicle is started, lock-up eliminates power loss in the torque converter and improves fuel efficiency. For this reason, a drive system using a continuously variable transmission has also been proposed in which a torque converter with a lockup is provided on the input side.

In the case of this continuously variable transmission with lockup, the vehicle starts at the lowest gear with the maximum gear ratio, and after the start of gear shifting, the gears are shifted steplessly and there is no need to switch to the torque converter in this gear shifting range. Therefore, the torque converter is activated to utilize torque amplification when the gear ratio is maximum at the time of starting, and the lock-up clutch is engaged and held in the gear shift range. Furthermore, the applicant has already proposed that the clutch be released at a predetermined vehicle speed at which the engine braking effect due to downshifting does not become excessive during deceleration, and the operation of the torque converter be switched again.

By the way, when driving in a cold state when the engine cooling water temperature is low, especially when the throttle opening is small, the engine output is insufficient and the engine speed fluctuates greatly. If the lock-up clutch is engaged at the same time as the start of a shift in such an engine state, fluctuations in the engine speed will be transmitted as they are, and this will adversely affect the start of the shift. In addition, in situations where quick upshifts are performed under low load conditions, power fluctuations due to gear shifting may further increase, impairing driving performance, etc. If engine output is unstable in this regard, the lock-up clutch should be It needs to be controlled separately.

Conventionally, there is a prior art technique disclosed in Japanese Patent Application Laid-Open No. 58-203259, for example, regarding low temperature measures for this type of continuously variable transmission. Here, in the case of low-load operation at low temperatures, it is shown that the gear is changed based on a corrected throttle opening that is larger than the actual throttle opening, and the downshift is corrected to the side with a larger gear ratio to increase the engine speed. has been done.

[Problem to be solved by the invention]

By the way, in the prior art described above, downshift correction at low temperatures is effective in reducing fluctuations in engine speed, etc., but there are limits to the correction.

Therefore, even if the downshift is corrected, if the gear is locked up in the shift range as usual, there are problems such as poor driving performance especially under low loads.

The present invention has been made in view of these points, and its purpose is to optimize lock-up control when engine output is unstable due to low temperatures, etc., and to improve running performance, vibration noise, etc. An object of the present invention is to provide a control device for a continuously variable transmission equipped with a fluid coupling with lockup.

[Means to solve the problem]

In order to achieve the above [1], the control device for a continuously variable transmission of the present invention includes a fluid coupling with a lock-up clutch on the input side of the continuously variable transmission, so that the lock-up region by the lock-up clutch can be controlled at heavy speeds, when the engine is In a control system controlled by functions of rotational speed, boolean ratio, and speed ratio, there is a means for determining the state of engine output based on water temperature, etc., and an operating range of the fluid coupling is expanded to the speed change range of the continuously variable transmission. low-temperature lock-up determining means for determining lock-up by searching a predetermined area map; and normal lock-up determining means for determining lock-up at least at the start of gear shifting;
``Switching means for selecting one of the low-temperature lockup determining means according to the state of engine output.

[For production]

Based on the above configuration, the state of the engine output is constantly judged based on water temperature, etc., and if the engine output is stable, the fluid coupling is activated at the time of starting, and the lock-up clutch is engaged when the continuously variable transmission starts shifting, and the lock-up range is reached. become. In addition, if the engine output at low temperatures is unstable, the lockup determination section is switched to the low-temperature lockup determination section, and at particularly low loads, the range map maintains the entire gear shift area within the fluid coupling operating range, and the fluid coupling allows the engine speed to fluctuate. It absorbs and alleviates the impact, ensuring driving force during upshifts.

〔Example〕.

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

Referring to FIG. 2, an outline of the drive system of a continuously variable transmission with a lock-up converter will be described. Reference numeral I designates an engine, in which the crankshaft 2 is connected to a torque converter device 31, a forward/reverse switching device 4. Continuously variable transmission 5 and differential device 6
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 IO. 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 10, 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, and a turbine shaft I3 is manually powered by a sun gear 1Ela, and is output from a carrier 16h to a primary shaft 20.

A forward clutch I7 is provided between the sun gear l[la and the ring gear IBc, and a reverse brake 18 is provided between the ring gear 18c and the case, and when the forward clutch 17 is engaged, the planetary gear 16 is integrated with the turbine shaft I3. It is directly connected to the primary shaft 20. 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 21 on a 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 primary cylinder 21 is set to have a larger pressure-receiving area, and due to the primary pressure, the winding of the drive belt 2B around the primary pulley 22 and the secondary pulley 25 changes the ratio of diameters so that the speed is 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
is connected to left and right wheels 33 via an axle 32.

On the other hand, in order to obtain a high oil pressure source for controlling the continuously variable transmission, the continuously variable transmission 5 is provided with a main oil pump 34, and this main oil pump 34 is directly connected to the crankshaft 2 via a pump drive shaft 35. In addition, the torque converter 12
．． In order to obtain a low hydraulic pressure source for lock-up clutch 15 and forward/reverse switching control, torque converter device 3 is provided with sub-oil pump 36, and sub-oil pump 3B is directly connected to converter cover 11 via pump shaft 37.

In FIG. 3, the hydraulic control system will be described.

First, regarding the continuously variable transmission hydraulic control system, the line pressure oil passage 41 from the high-pressure main oil pump 34 communicating with the oil pan 40 communicates with the line pressure control valve 42 to generate high line pressure. Line pressure is constantly supplied to the secondary cylinder 24 via the oil passage 43. The line pressure is further led to a speed change control valve 45 via an oil passage 44, and oil is supplied to and discharged from the primary cylinder 21 through an oil passage 4B to generate primary pressure. In addition, a working pressure oil passage 47 from a sub-oil pump 36, which will be described later, communicates with a reducing valve 48 so that a constant oil pressure is always generated.
This reducing oil passage 49.50 is the line pressure control valve 4.
2 solenoid valve 51. It communicates with the solenoid valve 52 of the speed change control valve 45.

The solenoid valve 51 is turned on and off by a duty signal from the control unit 80 to generate a pulsed control pressure, which is smoothed by the accumulator 53 and acts on the line pressure control valve 42 . and gear ratio I.

Depending on engine torque TO, torque converter torque amplification factor, etc., line pressure P1. control.

Similarly, a pulse-like control pressure is generated in the solenoid valve 52 of the speed change control valve 45 by the duty signal, and the speed change speed control valve 45 is operated in two positions: oil supply and oil drain.

Then, the operating state of the two positions is changed by the duty ratio to control the flow rate of oil supply and discharge to the primary cylinder 21, and the speed change control is performed by changing the speed ratio l and the changing speed dl/dt.

Next, regarding the hydraulic control system such as the torque converter, the oil passage 60 from the sub-oil pump 3B communicates with the regulator valve 61, and a predetermined low operating pressure is generated.

The operating pressure oil passage 62 communicates with a lock-up control valve 68 , which communicates with the torque converter 12 through an oil passage 64 and with the release chamber 86 of the lock-up clutch 15 through an oil passage 65 . On the other hand, the above-mentioned reducing pressure oil passage 68 communicates with the solenoid valve 67 of the lock-up control valve 63. If there is no lock-up signal from the control unit 80, oil path B
2 and 65 supply oil to the torque converter 12 via the release chamber 66, and when a lock-up signal is output, the operating pressure is supplied to the lock-up clutch 15 through oil passages B2 and 64.
It acts on and locks up.

Further, an operating pressure oil passage 69 branching from the oil passage 62 is connected to a select valve 70 . Forward clutch 17. via oil passages 71 and 72. It communicates with the reverse brake 18. The select valve 70 is for parking (P) and reverse (R).

It is switched according to the neutral (N) and drive (D) ranges. In the D range, the forward clutch 17 is supplied with oil through oil passages 69 and 71, and in the R range, the reverse brake 18 is supplied with oil through oil passages 69 and 72. Refuel P,
In the N range, the forward clutch 17 and reverse brake 18 are drained.

The electronic control system will be described in FIG.

First, engine rotation speed Ne, primary pulley rotation speed N
p, secondary pulley rotation speed Ns, throttle opening θ,
It has shift position sensors 81 to 85.

Therefore, regarding the speed change control system, in the control unit 80, the primary pulley rotation speed Np and the secondary pulley rotation speed Ns of the primary pulley rotation speed sensor 82 and the secondary pulley rotation speed sensor 83 are determined by the actual speed ratio calculation unit 8.
B manually, and the actual gear ratio i is determined by the actual gear ratio 1-Np/Ns.
Calculate. This actual gear ratio I and throttle opening sensor 8
4, the throttle opening θ and the shift position of the shift position sensor 85 are manually input to the primary rotation speed search unit 87, and are determined based on the shift pattern for each range of RID and sporty drive (Ds). Search for the target brake rotation speed NPD using the table below. The target primary pulley rotation speed NPD and the secondary pulley rotation speed Ns are input to the [1 standard gear ratio calculation unit 88, and the target gear ratio 1
s is calculated by l5-NPD/Ns.

Then, this target gear ratio 1s is manually input to the target gear ratio change speed calculating section 89, and a target gear ratio change speed dis/di is calculated based on the amount of change in the target gear ratio 1s over a certain period of time. And these actual gear ratios are 1. The target speed ratio Is and the target speed ratio change speed dis/di are input to the speed change speed calculation 1' 1190, and the speed change speed d1/dL is calculated as follows.

1 for di/dL- (ts-1) + 2 for dls/dt
In the above formula, K1, 2 is a constant, 1s-1 is [1
The control amount of the deviation between the target and actual gear ratio, diS/dL, is a delay correction element of the control system.

The shift speed dl/dt and the actual gear ratio l are manually input to the duty ratio search section 91. Here, since the duty ratio of the manipulated variable is set in the relationship D - f (di/dL, l), search using a table with a duty ratio of di/dL-1 for upshifts and downshifts. be done. This duty signal is then transmitted to the drive unit 105.
It outputs to the solenoid valve 52 via.

Regarding the lock-up control system, the engine rotation speed sensor 81. It has a speed ratio calculating section 92 that manually calculates the engine speed No. of the primary pulley rotation speed sensor 82 and the primary pulley rotation speed Np, and calculates the speed ratio e of the torque converter output side by e-Np/No. This speed ratio e and engine speed NO are input to the torque converter state determination section 98. Here, the set speed ratio e5 is set to determine the converter region and the coupling region of the torque converter 12, but the rotational speed difference ΔN (N.

In order to reduce the shock under the condition that -N p) is small, the set speed ratio es is set as an increasing function of the engine speed NO, and for this set speed ratio es, e≧e5
It is determined that it is a coupling region if .

Further, the lockup range by the lockup clutch 15 can also be controlled by a function of the vehicle speed, engine speed No., boolean ratio, and speed ratio e.

The above-mentioned target gear ratio Is is manually inputted to the shift start determination unit 94, and when the mechanically maximum gear ratio of the continuously variable transmission 5 is 2.5, the target gear ratio Is is set to S≧2.5 before the shift starts. ratio 1
If s is Is<2.5, it is determined that the shift has started. Here, in the target gear ratio calculation unit 88 of the electronic control system, even in a region where the target gear ratio IS is larger than 2.5, it is calculated based on the ratio of the target bridle pulley rotation speed NPD and the secondary pulley rotation speed Ns, Therefore, when the target speed ratio Is reaches a predetermined value larger than 2.5, taking into account the delay of the control system, it is determined to start shifting.

Then, in the above torque converter state, shift starts.

Signals for the shift position and secondary boot rotation speed Ns are manually input to the lock-up determining section 95, and the signals for the speed ratio e and the set speed ratio e are input manually.
, coupling judgment where e≧e.

Shift start judgment, range of D or Ds, secondary rotation speed pulley Ns and secondary pulley rotation speed setting value NSO
If Ns≧N5o is satisfied, lock-up Φ of lock-up clutch 15 is determined to be turned on. This lock-up signal is then output to the solenoid valve 67 via the drive section 96.

Regarding the line pressure control system, the engine torque calculation unit 9 manually calculates the throttle opening θ and the engine speed No.
7, and the engine torque To is determined from the torque characteristics. In addition, in response to the change in the input torque to the continuously variable transmission 5 due to the torque amplification effect of the torque converter I2, the speed ratio e
It has a torque amplification factor search section 98 which inputs an input, searches for a torque amplification factor .alpha. using a table of torque amplification factors, and an input torque calculation section 99 which calculates an input torque TI by TI-.alpha.-Te.

On the other hand, the actual gear ratio 1 is determined by the required line pressure setting section too l: Manually calculates the required line pressure PLu per unit torque, and this and the input torque TI are manually input to the target line pressure setting section 101 to set the target line pressure PL. is calculated by PL −PLu・TI. Here 1. Due to the characteristics of the line pressure control valve 42, in order to correct the fluctuation of the line pressure maximum value PL■ as the pump discharge pressure changes depending on the engine speed No, the valve inputs the engine speed Ne and the actual gear ratio 1. It has a characteristic correction section 102.

Then, according to the table of Ne-1, the line pressure maximum value P
Always keep the L value constant. Such target line pressure P! 1. Maximum line pressure &! P Ls is the duty ratio search unit 103
The duty ratio corresponding to the maximum line pressure @ p l and the target line pressure PI is determined by the ratio of the target line pressure PL to the intestine. Output to 5I.

In the above configuration, countermeasures for lock-up control at low temperatures will be described.

First, a water temperature sensor 10 detects the engine cooling water temperature.
6, the water temperature Tw signal from the water temperature sensor 106 is manually input to the engine output determination section 107, and the engine output and its stability are determined based on the water temperature Tw.

In addition, in order to determine the lockup region when the engine output is low and unstable, the low temperature lockup determination section 10g
has. The low-temperature Kawaguchi pull-up determination unit 108 has the torque converter 12 area and the lock-up clutch 15 area set in advance in the gear shift pattern as shown in FIG. Gear ratio 1. The torque converter area is expanded in the area between the low load predetermined throttle opening θ and the lowest shift line LL below. And the actual gear ratio is 1. Brim pulley rotation speed Nρ and secondary pulley rotation speed Ns
This map is searched to determine the presence or absence of lockup, and a lockup signal is output.

The low-temperature lockup determination section tog and the lockup determination section 95 are connected to a switching section 109, and are configured to select and output one of them based on the determination result of the engine output determination section 107.

Next, the operation of the thus configured control device will be described.

First, when the engine 1 is started in the N or P range, the torque converter device 3 is driven by the crankshaft 2, but the engine power is not applied to the continuously variable transmission 5 because it is cut off by the forward/reverse switching device number. - side, at this time, the main oil pump 34. The sub oil pump 36 is driven, and the line pressure control valve 42 of the hydraulic control system is activated. A predetermined oil pressure is generated by the regulator valve R1 and the reducing valve 48. here,
Line pressure is supplied only to the secondary cylinder 24,
By shifting the drive belt 2B to the secondary pulley 25 side, a low speed gear with the maximum gear ratio is achieved. Furthermore, when the vehicle is stopped, a lock-up/off signal is output from the determining section 93 to the solenoid valve 67, and the lock-up control valve 63 is switched to the release side of the lock-up clutch 15.
The operating pressure is transferred to the torque converter 12 via the release chamber 66.
As a result, the lock-up clutch 15 is turned off and the torque converter 12 is activated.

Therefore, when shifting to the D range, the forward clutch 17 is supplied with oil by the select valve 70, so the planetary gear 1B is integrated to directly connect the turbine shaft 13 and the primary shaft 20, and is in the forward position. Therefore, engine power is manually applied to the primary shaft 20 of the continuously variable transmission 5 via the torque converter I2, and the primary pulley 22. The secondary pulley 25 and the drive belt 2B output the power of the low speed stage with the largest gear ratio to the secondary shaft 23, which is transmitted to the wheels 83 via the differential device IS, allowing the vehicle to travel even when the accelerator is released. Therefore, the vehicle starts when the accelerator is released or the accelerator is depressed.

By the way, at the time of starting with the maximum gear ratio, the torque converter 12 acts to amplify the torque by a small speed ratio e, and this amplification factor α is searched by the torque amplification factor search section 98, and the target line pressure PL increases by this amount. . Therefore, the line pressure by the line pressure control valve 42 increases according to the maximum gear ratio and engine torque, and the
The pressing force of the belt 26 in step 5 can transmit torque including torque amplification without slipping.

Moreover, this start is performed at the maximum gear ratio I of the gear shift pattern shown in FIG.
This is done at a lower speed than L, and the actual gear ratio is held at the maximum of 2.5. . However, in the transmission control system, as the secondary boost rotation speed Ns increases, the actual gear ratio i changes from this actual gear ratio l due to the increase in the secondary boost rotation speed Ns.
and throttle opening θ, [1 standard primary primary rotation speed NPD is equal to these E1 standard primary primary rotation speed N
From the PC and the secondary boost rotation speed Ns, the target gear ratio calculation unit 8g and the rl target gear change speed calculation unit 89 calculate the target gear ratio Is.
, the target gear ratio change speed dis/dt is calculated. Then, the shift speed calculation unit 90 calculates these target shift ratios,
Actual gear ratio I.

Shift speed dl by L1 target gear ratio change speed dis/dt
/dt is determined, and the duty ratio search unit 91 determines the operation amount relative to the duty ratio corresponding to the controlled amount.

Therefore, the condition is < 2.5, and the solenoid valve 52
When the duty signal is output and the speed change control valve 45 operates, and the primary cylinder 21 is supplied with oil and a primary pressure is generated, the maximum speed ratio 1. shown in FIG. .

The gear shift is started from a predetermined point P and an upshift is performed.

On the other hand, the shift start is determined by the shift start determination section 94, and the signal is sent to the lockup determination section 95 at the same time as the shift start.
Enter. At this time, torque converter state determination section 93
Now, the speed ratio e and the set speed ratio e.

The presence or absence of a coupling region is determined based on the relationship between
Normally, the lock-up is determined at the start of the gear shift by already being in the coupling region.

Therefore, with the output of the above lock-up signal, solenoid valve B
By switching the lock-up control valve B3 to the torque converter side, the operating pressure is confined in the torque converter ■2 and acts on the lock-up clutch ■5, and thus the lock-up clutch 15 engages with the drive plate 10. and lock up.

Therefore, the engine power is efficiently transmitted by the lock-up clutch ■5, and the maximum gear ratio IL and minimum gear ratio at the start of the shift shown in Fig. 5! 7. The entire gear shift range between 2 and 3 becomes locked up.

In this lock-up state, the torque amplification factor α also becomes 1 because the speed ratio is e-1, and from this point on, the line pressure is equal to the actual speed ratio!
and engine torque To.

By the way, the state of the engine output is determined in the engine output determination section 107 based on the water temperature Tv determined by the water temperature sensor 10B, and if the engine output is low and unstable in a cold state where the water temperature Tv is low, the switching section 109 is switched to the lockup determination section 108 for low temperature.

Therefore, in this case, the lock-up control associated with the start of the shift described above is separated, and lock-up control is performed using the map of the low-temperature lock-up determining section 108.

That is, when the throttle opening degree θ is relatively large as at point P in FIG. is absorbed and gear shifts start smoothly. Then, at the time point P' when an upshift is made to a predetermined actual gear ratio, a lock-up on signal is output from the low-temperature lock-up determining section 10g, and the lock-up clutch 15
is engaged. Furthermore, when starting a shift at a low load point Q, the low temperature Kawaguchi pull-up determination unit 108 holds the entire shift range in the torque converter region, so that fluctuations in engine speed are transmitted while being absorbed and alleviated by the torque converter 12. . In addition, with this low negative 61j, as the vehicle speed increases, the upshift is performed quickly, and since the engine output is in a state of decrease, the driving force is further reduced by the upshift, but the torque amplifying action of the torque converter 12 is activated as necessary. This will ensure driving force.

On the other hand, water+! ! When Tv rises and the engine enters a warm-up state, and a predetermined engine output is stably output, the switching section 109 switches to the normal lock-up determining section 95,
Returns to lock-up across the gear shifting range.

Although the embodiments of the present invention have been described above, the determination may be made using parameters other than the water temperature or by detecting the state of the engine output with a torque sensor or the like.

〔Effect of the invention〕

As described above, according to the present invention, in lock-up control of a continuously variable transmission equipped with a fluid coupling with lock-up, if the engine output at low temperatures is low and unstable, the fluid coupling is activated based on the region map. As we expand the area,
Fluctuations in engine speed are absorbed and alleviated, improving driving performance and reducing vibration and noise.

Furthermore, at low temperatures and low loads, the entire shifting area is in the fluid coupling operating range, which further increases the driving force.

In addition, at low temperatures and medium to high loads, by locking up after the shift starts, the shift can be started smoothly in the fluid coupling operating range.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a control device for a continuously variable transmission according to the present invention, FIG. 2 is a skeleton diagram showing an example of a continuously variable transmission, and FIG. 3 is a circuit diagram of the hydraulic control system. Figure 4 is a diagram showing a map of the fluid coupling operating range at low temperatures, and Figure 5 is a diagram showing the presence or absence of lock-up in the shift pattern. 5... Continuously variable transmission, 12... Torque converter, [
5... Lock-up clutch, 67... Lock-up solenoid valve, 80... Control unit, 95...
・Lockup determination section, 106...Water temperature sensor, 10
7...Engine output judgment section, 108...Lockup determination section for low temperature, 109...Switching section Fig. 2

Claims (2)

[Claims] (1) In a control system that includes a fluid coupling with a lock-up clutch on the input side of a continuously variable transmission and controls the lock-up area by the lock-up clutch according to a function of vehicle speed, engine speed, pulley ratio, and speed ratio, water temperature and low-temperature lock-up determining means for determining lock-up by searching a region map defined by expanding the operating region of the fluid coupling to the speed change region of the continuously variable transmission. , a continuously variable transmission comprising at least a normal lock-up determining means for determining lock-up at the start of a shift, and a switching means for selecting one of the low-temperature lock-up determining means according to the state of engine output. Control device. (2) The area map is characterized by defining the area between the maximum gear ratio and a predetermined gear ratio after the start of gear shifting in the case of medium and high loads, and the gear changing area in the case of low loads as the fluid coupling operating area. The control device for a continuously variable transmission according to claim (1).