JPH0814315B2 - Shift control device for continuously variable transmission - Google Patents

Description

The present invention relates to a shift control device for a continuously variable transmission.

(B) Conventional technology As a conventional shift control device for a continuously variable transmission, Japanese Patent Laid-Open No. 61-
There is one disclosed in Japanese Patent No. 105351. The continuously variable transmission shown in this figure has two ranges, a normal driving range D range and an engine brake traveling range S range. In the D range, the shift pattern is set in consideration of the fuel consumption rate so as to use the region where the engine speed is relatively low. On the other hand, the S range is similar to the D range on the high throttle opening side, but on the low throttle opening side, the engine rotation speed becomes higher compared to the D range at the same vehicle speed, that is, the gear ratio, that is, the gear ratio. A shift pattern in which the large area is used is set. As a result, when the driver selects the S range, the gear ratio becomes relatively large even when the throttle is fully closed.
The engine braking effect is increased and the acceleration force is also increased.

(C) Problems to be Solved by the Invention However, the conventional shift control device for a continuously variable transmission as described above has a problem that the storage capacity required for setting the shift pattern is large and the shift pattern There is a problem that the change is troublesome. That is, different shift patterns are set for the D range and the S range, and the shift patterns are stored in a predetermined storage device. The target engine rotation speed is read from a predetermined shift pattern depending on whether the D range or the S range is selected. As described above, since the shift patterns are stored in the D range and the S range, respectively, the storage capacity required for this is large. Further, if the shift pattern on the high throttle opening side of the D range is changed according to the vehicle type, engine specifications, etc., the corresponding portion of the S range must be changed accordingly. This work requires a large number of man-hours, and errors are likely to occur during data input. An object of the present invention is to solve such a problem.

(D) Means for Solving the Problems The present invention, in the case of the engine brake traveling range, increases the target engine rotation speed by applying a limiter to the shift pattern of the normal traveling range. To solve. That is, the shift control device for a continuously variable transmission according to the present invention uses a storage means that stores a target engine rotation speed as a function of an engine load (for example, a throttle opening) and a vehicle speed, and a predetermined vehicle speed only as a function of the vehicle speed. In the above, the rotation speed limiting means for generating a signal indicating the minimum target rotation speed of the engine, which is a constant value larger than the target engine rotation speed when the engine load is the smallest, and the storage means in the case of the normal traveling range. The target engine rotation speed from the engine is output as it is, and in the case of the engine braking range, the target engine rotation speed from the storage means is compared with the minimum target rotation speed of the engine from the rotation speed limiting means, and the larger value Means for outputting the target engine rotation speed, and a continuously variable transmission based on the target engine rotation speed from the selection means. Has a transmission ratio control means for controlling the gear ratio, the.

(E) Action When the normal travel range (D range) is selected, the target engine rotation speed obtained from the shift pattern stored in the storage means is input to the gear ratio control means, whereby the gear shift is performed. Ratio control is performed. On the other hand, when the engine brake traveling range (S range) is selected, the minimum target engine rotation speed obtained from the shift pattern of the storage means and the target engine rotation speed obtained from the rotation speed limiting means are The compared value is compared and the larger value is input to the gear ratio control means as the target engine speed. The rotation speed limiting means generates a minimum target rotation speed of the engine as a function of the vehicle speed, and the minimum target rotation speed of the engine is set higher than that of the shift pattern stored in the storage means on the low throttle opening side. There is.
Therefore, the minimum target rotation speed of the engine is higher than the target engine rotation speed obtained from the shift pattern of the storage means on the small throttle opening side. As a result, an effective engine braking action can be obtained in the S range, and a large driving force can be obtained.

(F) Embodiment FIG. 2 shows a power transmission mechanism of a continuously variable transmission. This continuously variable transmission has a fluid coupling 12, a forward / reverse switching mechanism 15,
It has a V-belt type continuously variable transmission mechanism 29, a differential device 56, and the like, and can transmit the rotation of the output shaft 10a of the engine 10 to the output shafts 66 and 68 at a predetermined gear ratio and rotation direction. This continuously variable transmission is equipped with a fluid coupling 12 (lockup oil chamber 12a, pump impeller 12b, turbine runner 12c.
Etc.), rotary shaft 13, drive shaft 14, forward / reverse switching mechanism 15, drive pulley 16 (fixed cone member 18, drive pulley cylinder chamber 20 (chamber 20a, chamber 20b), movable cone member 22, groove)
22a), planetary gear mechanism 17 (including sun gear 19, pinion gear 21, pinion gear 23, pinion carrier 25, internal gear 27, etc.), V belt 24, driven pulley 26 (fixed cone member 30, driven pulley cylinder). (Chamber 32, movable cone member 34, etc.), driven shaft 28, forward clutch 40, drive gear 46, idler gear 48, reverse brake 5
0, idler shaft 52, pinion gear 54, final gear 4
4, pinion gear 58, pinion gear 60, side gear 62,
The side gear 64, the output shaft 66, the output shaft 68, and the like are included, but detailed description thereof will be omitted. Note that the configuration of the part of which description is omitted is described in Japanese Patent Application Laid-Open No. 61-105353 filed by the present applicant.

FIG. 3 shows a hydraulic control device for a continuously variable transmission. The hydraulic control device includes an oil pump 101, a line pressure regulating valve 102, a manual valve 104, a shift control valve 106, an adjustment pressure switching valve 108, a shift motor (step motor) 110, a shift operation mechanism 112, a throttle valve 114, a constant pressure. It has a pressure regulating valve 116, an electromagnetic valve 118, a coupling pressure regulating valve 120, a lock-up control valve 122, and the like, which are connected to each other as shown in the drawing, a forward clutch 40, a reverse brake 50, The fluid coupling 12, the lock-up oil chamber 12a, the drive pulley cylinder chamber 20, and the driven pulley cylinder chamber 32 are also connected as illustrated. Detailed description of these valves and the like will be omitted. The parts for which the description has been omitted are described in
No. 105353. Each reference numeral in FIG. 3 indicates the following member. Pinion gear 110a, tank 13
0, strainer 131, oil passage 132, relief valve 133, valve hole 13
4, ports 134a-e, spool 136, lands 136a-b, oil passage 138, one-way orifice 139, oil passage 140, oil passage 142, one-way orifice 143, valve hole 146, ports 146a-g, spool
148, lands 148a-e, sleeve 150, spring 152,
Spring 154, transmission ratio transmission member 158, oil passage 164, oil passage 16
5, orifice 166, orifice 170, valve hole 172, port 17
2a-e, spool 174, land 174a-c, spring 17
5, oil path 176, orifice 177, lever 178, oil path 179, pin 181, rod 182, lands 182a-b, rack 182c, pin
183, pin 185, valve hole 186, ports 186a-d, oil passage 188, oil passage 189, oil passage 190, valve hole 192, ports 192a-g, spool 1
94, lands 194a-e, negative pressure diaphragm 198, orifice 199, orifice 202, orifice 203, valve hole 204, ports 204a-e, spool 206, lands 206a-b, spring 208, oil passage 209, filter 211, orifice 216. , Port 222, solenoid 224, plunger 224a, spring 22
5, valve hole 230, ports 230a-e, spool 232, land 232
ab, spring 234, oil passage 235, orifice 236, valve hole
240, ports 240a-h, spool 242, lands 242a-e,
Oil passage 243, oil passage 245, orifice 246, orifice 247, orifice 248, orifice 249, choke type throttle valve 250,
Relief valve 251, Choke type throttle valve 252, Holding pressure valve 25
3, oil passage 254, cooler 256, cooler pressure holding valve 258, orifice 259, changeover detection switch 278.

FIG. 4 shows a shift control device 300 that controls the operation of the step motor 110 and the solenoid 224. Shift control device 300
Is an input interface 311, a reference pulse generator 312,
CPU (Central Processing Unit) 313, ROM (Read Only Memory) 3
14, it has a RAM (random access memory) 315 and an output interface 316, which are address buses 319.
And data bus 320. The shift control device 300 includes an engine rotation speed sensor 301, a vehicle speed sensor 302, a throttle opening sensor 303, a shift position switch 304, a turbine rotation speed sensor 305,
The signals from the engine cooling water temperature sensor 306, the brake sensor 307 and the changeover detection switch 298 are input directly or through the waveform shapers 308, 309 and 322 and the AD converter 310, while the step motor 110 is transmitted through the amplifier 317 and the lines 317a to 317a-d. Signal is also output to the solenoid 224, but detailed description thereof will be omitted. The structure of the part whose description is omitted is described in the above-mentioned JP-A-61-105353.

FIG. 5 shows a flowchart of shift control performed by the shift control device 300. First, the throttle opening signal TH
Is read (step 102), then the vehicle speed signal V _s is read (step 104), and the target engine speed N is read from both signals TH and V _s.
Search e (106). The search for Ne is performed based on TH and V _s from the shift pattern set in the map of the storage device. That is, as a map, as shown in FIG.
Target engine rotation speed corresponding to the vehicle speed signal V _s when the throttle opening signal TH has eight stages of 1/8
Ne is set. After completing the search for Ne, it is determined whether the select lever is in the D range (108). D
In the case of the range, the process directly proceeds to step 116 described later. In the case of the S range, the process proceeds to step 110 and the limit value L
Search for. As the limit value L, the minimum target engine speed of the engine is set as a function of the vehicle speed V _s as shown in FIG. The limit value L is set to a value larger than the target engine rotation speed Ne of the shift pattern in the region where the throttle opening signal TH of the shift pattern shown in FIG. 6 is small.
Next, the target engine speed N retrieved in step 106
The value e is compared with the limit value L retrieved in step 110 (step 112), and if Ne is L or more, the process proceeds to step 116. On the other hand, if Ne is less than L, the value of Ne is L. Value is set (step 114), and the routine proceeds to step 116. Step 11
At 6, the target speed ratio i is calculated from the target engine speed Ne, the vehicle speed V _s, and the multiplier k, and then the step position of the step motor 110 corresponding to this target speed ratio i is calculated (see the same 1
18) Then, a signal for driving the step motor 110 to reach this step position is output (step 120).

According to the control flow shown in FIG. 5, the following shift control is eventually performed. That is, in the case of the D range which is the normal traveling range, the gear ratio is controlled so that the target engine rotation speed is in accordance with the gear shift pattern preset in the storage device. As the shift pattern, a pattern with a high fuel consumption rate is set which uses a region where the engine speed is relatively low. On the other hand, when the S range is selected, in a region where the target engine rotation speed is higher than the limit value L, that is, in a region where the throttle opening is large, the target engine rotation speed according to the shift pattern set in the same manner as above is set. The gear ratio is controlled so that However, even at a low throttle opening, the target engine rotation speed does not fall below the limit value L, so the target engine rotation speed is set to a relatively high value. As a result, the gear ratio becomes large even with a low throttle opening, and an effective engine braking action can be obtained. Further, since the gear ratio is large, the driving force also becomes large. In order to perform such control, it suffices to preset the limit value L as shown in FIG. 7, and in addition to the shift pattern for the D range, the shift pattern for the S range as well. The required storage capacity is about half compared to the case where it is stored in the storage device in advance. Since only one type of shift pattern is set, only one type of shift pattern needs to be changed when changing the shift pattern. As a result, the shift pattern for the S range is also changed.

(G) Effect of the Invention As described above, according to the present invention, in the engine brake traveling range, the limiting means for setting the target engine rotation speed to a value equal to or higher than the minimum target rotation speed of the engine is provided. Only one type needs to be stored, the required storage capacity is reduced, and the shift pattern can be changed easily. Further, the minimum target rotation speed is a function of only the vehicle speed, and above a predetermined vehicle speed, the engine load is the largest. Since it is set to be a constant value that is larger than the target engine rotation speed when it is small, it is possible to maintain a relatively high target engine rotation speed even in a low vehicle speed region, and it is possible to achieve a good low speed region. The effect of engine braking can be sustained.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between components of the present invention, FIG. 2 is a skeleton diagram of a continuously variable transmission, FIG. 3 is a diagram showing a hydraulic control circuit of the continuously variable transmission, and FIG. The figure which shows the control device of the transmission,
FIG. 5 is a diagram showing a control flow, FIG. 6 is a diagram showing a shift pattern, and FIG. 7 is a diagram showing characteristics of a limit value.

Claims (1)

[Claims] 1. A transmission control device for a continuously variable transmission having a normal travel range and an engine brake travel range, and a storage means for storing a target engine rotation speed as a function of an engine load and a vehicle speed, Rotation speed limiting means for generating a signal indicating the minimum target rotation speed of the engine, which is a function of only the vehicle speed and has a constant value that is larger than the target engine rotation speed when the engine load is the smallest at a predetermined vehicle speed or more; In the case of the operating range, the target engine rotation speed from the storage means is output as it is. In the case of the engine braking range, the target engine rotation speed from the storage means and the minimum target rotation speed of the engine from the rotation speed limiting means are output. And a larger value is output as the target engine speed, and the target engine from the selecting means. And a gear ratio control means for controlling the gear ratio of the continuously variable transmission based on the gin rotation speed.