JPS6239299B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slip control method for a lockup torque converter.

Since the torque converter transmits torque through fluid, it itself has a function of absorbing torque fluctuations and transmits power smoothly, but on the other hand, it has the drawback of poor power transmission efficiency.

Therefore, a lock-up torque converter has been proposed which has a transmission path for transmitting power from the prime mover to the output shaft via a torque converter, as well as a transmission path for directly transmitting power to the output shaft via an appropriately connected direct coupling clutch. When this lock-up torque converter engages a direct coupling clutch, the direct coupling clutch transmits power directly to the output shaft without going through the torque converter, improving power transmission efficiency. However, in the engaged state of the direct coupling clutch, the torque converter cannot be expected to have a torque fluctuation absorbing function, and therefore, depending on the operating state of the prime mover, it is difficult to expect smooth torque transmission and vibrations may occur.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 57-33253, the slip between the rotational speed of the prime mover (input element rotational speed of the torque converter) and the output element rotational speed of the torque converter is detected from the difference between the two. Techniques have been proposed to keep the slip constant. However, since this technology connects and controls the lock-up torque converter's direct coupling clutch by detecting slip, the slip is detected after the slip changes due to a change in engine output, so there is a delay in the detection. In some cases, control tends to be delayed, making it difficult to obtain accurate control.
Furthermore, the optimal degree of occurrence of the above-mentioned slip in relation to the output shaft torque that should originally be controlled varies depending on variations in the torque transmission characteristics of the torque converter, that is, manufacturing tolerances of the torque converter, etc., and as a result, it is necessary to avoid variations in control accuracy. Therefore, the desired control cannot necessarily be achieved.

Therefore, as shown in U.S. Pat. No. 4,002,228, the internal pressure of the torque converter is guided to the direct coupling clutch using a variable orifice that responds to the torque generated in the turbine of the torque converter, and the coupled state of the direct coupling clutch is changed due to fluctuations in torque. Techniques have also been proposed to control the transmission of but,
With this technology, the coupling state of the direct coupling clutch is controlled only according to the output torque of the torque converter, regardless of the operating state of the prime mover, so the control is performed to eliminate vibration after it has occurred. The occurrence of vibration cannot be avoided under some operating conditions such as the above, and it cannot be a perfect countermeasure.

The present invention eliminates the above-mentioned delays and variations and eliminates some of the vibrations by controlling the connection state of the direct coupling clutch so that the output shaft torque of the torque converter is always at a value commensurate with the operating state of the prime mover. From the viewpoint that it is possible to carry out slip control of a lock-up torque converter to ensure that vibration does not occur at all times without causing such problems, this idea has been realized, and for this purpose, the present invention has been developed. The lock-up torque converter slip control method directly detects the torque transmitted to the output shaft that should be controlled, sets the target output shaft torque based on the operating state of the prime mover, and then adjusts the torque transmitted to the output shaft to the set output. The purpose is to control the connection of a direct coupling clutch to achieve shaft torque. Furthermore, the present invention eliminates waste by controlling the connection of the direct coupling clutch at this time, since such control is really necessary when the transmission torque changes suddenly, which may cause vibration.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows a lock-up torque converter to be subjected to slip control according to the method of the present invention, in which 1 is a torque converter and 2 is a direct clutch. A pump impeller 3 of the torque converter 1 is connected to a drive plate 5 via a converter cover 4, and this drive plate is connected to a rotating shaft 6 of a prime mover. Further, the turbine runner 7 of the torque converter 1 is riveted to a turbine hub 8, and the turbine hub is rotatably fitted onto a shaft hub 10 spline-coupled to the torque converter output shaft 9. Furthermore, the stator 11 of the torque converter 1 is mounted on the sleeve 13 via a one-way clutch 12. The sleeve 13 is integrally formed and fixed to the pump cover 15 of the gear pump 14, and the gear pump 14 is housed between the pump cover 15 and the pump housing 16, and the pump is driven by a hollow drive shaft 17 connected to the pump impeller 3. Drive.

An annular hydraulic oil supply passage 18 toward the inside of the torque converter 1 is set between the shaft 17 and the sleeve 13,
Hydraulic oil from gear pump 14 can be supplied into torque converter 1 through this passage. Three spacers 19 between the output shaft 9 and the sleeve 13
- 21 are inserted to form two passages 22 and 23. The passage 22 is used as a hydraulic oil return passage for draining the return oil from the torque converter 1, and the passage 23 is used as a hydraulic oil return passage for lock-up control pressure, which will be described later. Each acts as a lock-up passage.

The direct coupling clutch 2 includes a lock-up clutch piston 24 which is slidably fitted onto the shaft hub 10 to partition the inside of the converter cover 4 into a converter chamber 25 and a lock-up chamber 26. The lockup clutch piston 24 is drivingly connected to the shaft hub 10 via an annular member 27 welded thereto, and the shaft hub 10 and the turbine hub 8 are drivingly connected by a torsion spring 28.

The lock-up chamber 26 is a hole 29 provided in the output shaft 9.
This communicates with the lockup passage 23, and this passage is connected to the port 30a of the lockup control valve 30. The lock-up control valve 30 also has a port 30b to which the pressure inside the converter chamber 25 is introduced.
and a drain port 30c, and when the spool 30e is moved to the left in the figure against the spring 30f, the port 30a is changed to the port 30c, and when the spool 30e is returned to the right position in the figure, the port 30a is changed to the port 30c. The port 30b is connected to the port 30a, and the port 30a is connected to the ports 30b and 30c at an intermediate position.

The chamber 30d is connected to a forward running pressure passage 32 of the automatic transmission through a fixed orifice 31, and to a drain port 34 through a fixed orifice 33, with a lock-up solenoid 35 disposed opposite the fixed orifice 33. Lock-up solenoid 3
Reference numeral 5 indicates that the plunger 35a is normally in the retracted position and is open so that the fixed orifice 33 communicates with the drain port 34, and when energized, it is advanced and closed so as to block the fixed orifice 33 from the drain port 34.

The lockup torque converter described above operates as follows.

When the lock-up solenoid 35 is de-energized and the plunger 35a opens the fixed orifice 33, the chamber 30d is depressurized by the drain port 34, and the spool 30e is in the rightward position connecting the port 30a to the port 30b. . Therefore,
Torque converter internal pressure from port 30b is supplied into lockup chamber 26 through port 30a, passage 23, and hole 29, and this chamber is connected to converter chamber 25.
, the lock-up clutch piston 24 is not pressed against the end wall of the converter cover 4. Therefore, the power from the shaft 6 is transferred to the drive plate 5, converter cover 4, torque converter 1, turbine hub 8, and torsion spring 2.
8. Power is transmitted to the output shaft 9 via a transmission path passing through the shaft hub 10, and the lockup torque converter transmits power in a so-called converter state.

When plunger 35a closes fixed orifice 33 due to activation of lock-up solenoid 35, chamber 30d is brought to the same value as the forward pressure from passage 32. The pressure inside this chamber 30d is the spool 30e.
is moved to the left position against spring 30f, and port 3
0a to the drain port 30c. Therefore, the pressure inside the lockup chamber 26 is reduced through the hole 29, the passage 23, and the port 30a to the drain port 30c.
More removed, lockup clutch piston 2
4 is pressed against the end wall of the converter cover 4 by the pressure in the converter chamber 25, so that the direct coupling clutch 2 is in the engaged state. At this time, the power from the shaft 6 is transmitted to the output shaft 9 via a transmission path passing through the drive plate 5, converter cover 4, lock-up clutch piston 24, and shaft hub 10, and the lock-up torque converter transmits power in a so-called lock-up state. Do this.

Then, the lock-up solenoid 35 is energized.
When deenergization is repeated and the energization time width is duty-controlled as described below, as the duty increases, the pressure in the chamber 30d increases, and the spool 30e connects the port 30a to both ports 30b, 30c.
However, the degree of communication with the port 30b is gradually decreased, and the degree of communication with the port 30c is gradually increased. Therefore, the pressure in the lockup chamber 26 decreases as the duty increases, and the pressure in the lockup chamber 26 decreases as the duty increases.
The bonding state of can be controlled so that the bonding force gradually increases.

In the present invention, the lockup torque converter is provided with means for detecting the torque transmitted to the output shaft 9 as described below. That is, as shown in FIGS. 1 and 2, permanent magnets 36 and 3 are arranged in the same rotational plane in the shaft hub 10 and the turbine hub 8, respectively.
7 are provided, and these permanent magnets are arranged with their positions shifted in the rotational direction. Then, the permanent magnet 37 is passed through the long hole 10a in the rotational direction of the shaft hub 10,
Like the permanent magnet 36, it is made to face the outer peripheral surface of the sleeve 13. In addition, a reed switch 38 is embedded in the outer peripheral surface of the sleeve 13, and is connected to the permanent magnets 36, 37.
, so that the reed switch 38 is closed each time the permanent magnets 37, 36 approach the reed switch 38 while the hubs 8, 10 are rotating.

It is also possible to replace the permanent magnets 36 and 37 with mirrors that reflect light, and correspondingly replace the reed switch 38 with a light emitting diode and a phototransistor, or use other magnetoresistive elements, wheel elements, etc.

In this transmission torque detection means, while torque is not being transmitted, the turbine hub 8 and the shaft hub 10 are in the relative positions shown in FIG. 2, and the permanent magnet 37 is in the position shown by the solid line with respect to the permanent magnet 36. At this time, since the hubs 8 and 10 are being rotated in the direction of the arrow in FIG.
8 is first closed by a permanent magnet 37 during one rotation period T to generate an output pulse P ₁ , and then closed by a permanent magnet 36 to generate an output pulse P ₂ , as shown in FIG. The pulse interval of the pulses is t _nio . By the way, when the torque transmitted to the output shaft 9 increases in the converter state, the turbine hub 8 compresses the torsion spring 28 with respect to the shaft hub 10 and rotates relative to the shaft hub 10 in the forward rotation direction in balance with the spring reaction force. , permanent magnet 37
is displaced relative to the permanent magnet 36, for example, to the position shown by the imaginary line in FIG. Therefore, the permanent magnet 36,
The output pulse of reed switch 38 is closed by these permanent magnets as the interval between 37 increases.
P ₁ and P ₂ increase the pulse interval as shown by t in FIG. 3b. In the lock-up state, no power is transmitted through the torque converter 1, so the pulse interval is t _nio .

In the present invention, the lock-up solenoid 35 is further controlled by, for example, a microcomputer shown in FIG. The microcomputer includes a central processing unit (CPU) 39, a read-only memory (ROM) 40, a random access memory (RAM) 41, and an input/output interface circuit 42.
In addition to the output pulse interval t from the reed switch 38, the engine rotation speed sensor 43
The engine speed signal N _E from
Gear position signal TM output from the gear position sensor 44 of an automatic transmission as shown in Publication No. 47056
and a throttle opening signal TH of the prime mover (engine) from a throttle sensor 45 are input to the CPU 39 via an input/output interface circuit 42. Then, the CPU 39 receives the fifth input signal from these input signals.
The calculation results based on the control program shown in the figure are output to the drive circuit 46 via the input/output interface circuit 42, and the lock-up solenoid 3
5 is controlled as follows.

That is, the CPU 39 first executes the block 50 in FIG.
The gear position of the automatic transmission is read from the gear position signal TM from the sensor 44 at the next block 5.
By comparing the read gear position in step 1 with the previous read gear position temporarily stored in the RAM 41, it is determined whether or not the automatic transmission should shift based on whether the two are different. If the gear is not changed, the control proceeds sequentially to blocks 52 and 53. In block 52, the throttle opening signal TH from sensor 45 is read, and in block 53, the engine rotational speed signal N _E from sensor 43 is read. In the next block 54, based on the read throttle opening signal TH and engine speed signal N _E , the prime mover currently locks up the torque converter, and the direct coupling clutch 2 The converter is in the operating range where the converter is released (hereinafter referred to as the A/T range) or the converter is in the locked-up state where the direct coupling clutch 2 is engaged (hereinafter referred to as the L/T range).
It is determined whether the operating range is in the u range (hereinafter referred to as the S/L range) or in the operating range in which coupling control is to be performed while the direct coupling clutch 2 is slipped (hereinafter referred to as the S/L range).

If it is in the S/L region, the control proceeds to block 55, in which the output pulse interval of the reed switch 38 is temporarily set to a predetermined initial value t _nio (the maximum value may be used) only when the prime mover is started, and this is
Store it in RAM41. In addition, in the processing after starting, block 55 is only passed. In the next block 73, since there is no comparison target for the pulse interval to be read first, the corresponding t ₀
(which may be zero), and also set a set pulse interval t _a corresponding to the set value of the torque change rate. Note that this t _a corresponds to the lower limit value of the torque change rate that may cause vibration. In the next block 67, as will be described later in blocks 56 to 58, the reading number n of the reading pulse interval t is 1<
It is determined whether n≦m, that is, whether the number of readings has not reached the predetermined number m. If not, control proceeds to block 68, where n=1.
The number of reads is counted up sequentially from . When the number of readings n reaches the specified number m, block 67 selects block 56, and further reading is temporarily interrupted here. In block 56, the output pulse interval t from the reed switch 38 is read, and in the next block 57, it is determined whether or not this is smaller than the initial value t _nio . If so, control passes to block 58 where t is equal to t _nio ; otherwise, block 58 is bypassed;
The next control is executed using the read t itself as the pulse interval. During the reading of the pulse interval, the nth read value t is read in block 69.
_o is temporarily stored in the RAM 41 as t, and read values t ₁ to t _n are sequentially stored in the RAM 41 by setting n=n+1 in blocks 75 and 76 described later.

In the next block 74, it is determined whether or not the absolute value of the difference between the current reading pulse interval t _o and the previous reading pulse interval t _{o -1} (initially the above-mentioned t ₀ ) is smaller than the set value t _a . Determine whether there is a sudden change in torque that would cause this. If so, block 63 is selected via block 76, and duty maintenance is thereby executed; otherwise, if the torque change is greater than or equal to the set value, control proceeds via block 75 to block 59, and the following steps are performed. The following control of the direct coupling clutch 2 is executed.

That is, in the next block 59, the pulse interval t is subtracted by the pulse interval t _ij corresponding to the set output shaft torque read from the table shown in FIG. 7 stored in the ROM 40. Here, the table in FIG. 7 shows the pulse interval corresponding to the set output shaft torque for each driving state of the prime mover expressed by the engine speed and throttle opening.
Based on the signals TH and _NE read from blocks 52 and 53, the CPU 39 reads out the pulse interval t _ij at the corresponding address from the ROM 40 using a table lookup method, and can perform the above-mentioned subtraction. Then, if the calculation result of t-t _ij is positive, that is, t>t _ij , and as is clear from the above, the torque transmitted from the turbine runner 7 to the output shaft 9 is larger than the set output shaft torque, the control The process proceeds to block 60 where the duty is increased. Therefore, the pulse signal sent by the block 61 to the lock-up solenoid 35 energizes the solenoid.
Even if the deenergization is repeated, the energization time becomes longer, increasing the pressure in the chamber 30d, lowering the pressure in the lockup chamber 26 through the action of the lockup control valve 30, and causing the coupling of the direct coupling clutch 2. Increase power. Thus, the torque transmitted from the turbine runner 7 to the output shaft 9 is reduced to the set output shaft torque.

Conversely, the calculation result of t-t _ij is negative, that is, t<t _ij
If the torque transmitted from the turbine runner 7 to the output shaft 9 is less than the set output shaft torque, control proceeds to block 62, where the duty is reduced. Therefore, the pulse signal sent to the lock-up solenoid 35 by the block 61 is such as to shorten the energization time of the solenoid, and the coupling force of the direct coupling clutch 2 is reduced inversely to the above, and the output shaft 9 is transferred from the turbine runner 7 to the output shaft 9. The torque transmitted to the output shaft can be increased to the set output shaft torque.

Furthermore, the calculation result of t-t _ij is zero, that is, t=t _ij
If the torque transmitted from the turbine runner 7 to the output shaft 9 is equal to the set output shaft torque, control proceeds to block 63 where the duty is maintained as it is. Thus, the pulse width of the pulse signal sent to the lock-up solenoid 35 by the block 61 does not change, the coupling force of the direct coupling clutch 2 is maintained as it is, and the torque transmitted from the turbine runner 7 to the output shaft 9 is set at the output. The shaft torque can be maintained. Note that it is natural that it is not necessary to strictly determine whether the calculation result of tt _ij is zero, positive, or negative based on this value, and a certain allowable range can be set.

Due to this action, the torque transmitted to the output shaft 9 is always maintained at a set value according to the operating state of the prime mover.
It is possible to reliably prevent the lockup torque converter from generating vibrations due to torque fluctuations under any operating condition of the prime mover. Moreover, in the present invention, the output shaft torque that should be originally controlled is directly detected, and the slip of the lock-up torque converter is controlled so that the output shaft torque becomes a set value according to the operating state of the prime mover. Unlike control that detects the difference in rotational speed of the torque converter output element, that is, slip, and keeps it constant, there is no delay in control, resulting in poor accuracy, or variation in accuracy, and the torque converter Unlike the control that detects only the torque generated in the turbine and eliminates its fluctuations, the problem of vibration once occurring does not occur. In addition, since the above control is performed only when the torque suddenly changes when vibration may occur, unnecessary feedback control is not executed, and the torque converter can be prevented from entering an inappropriate slip state. This can prevent a decrease in the durability of the lock-up solenoid 35 and an increase in the capacity of the computer.

If it is determined that the automatic transmission will change gears based on the determination result of block 51, the block selects block 64, clears the gear position previously stored in RAM 41, and reads the new gear position. Instead, it is stored in the RAM 41 in preparation for the next operation. Control then proceeds to block 65 where a lock up solenoid off command is issued and this command is applied to the lock up solenoid 35 at block 61. At this time, the lock-up solenoid 35 is deenergized and the direct-coupled clutch 2 is released as described above, thereby preventing the automatic transmission from shifting gears with the direct-coupling clutch 2 in the engaged state and causing a shift shock. can. This kind of release of the direct coupling clutch 2 is executed in the same way when it is determined in block 54 that the prime mover is operating in the A/T region, and the direct coupling clutch 2 is released as requested in the A/T region in FIG.
can be left free. Also, block 5
If it is determined in step 4 that the prime mover is operating in the L/U range, the control proceeds to block 66, where a lock-up solenoid ON command is issued, and this command is supplied to the lock-up solenoid 35 in block 61. . At this time, the lock-up solenoid 35 is energized, and as mentioned above, the direct coupling clutch 2 is completely engaged, and the sixth
The direct coupling clutch 2 can be completely engaged as required in the L/u region shown in the figure.

Note that the control according to the present invention described above is performed repeatedly every rotation of the lock-up torque converter or every fixed period of time, but it is necessary to perform accurate control with little torque fluctuation, such as during coasting (coasting) driving. If there is no change in throttle opening or engine speed, etc.
The control program of the microcomputer may be changed to the one shown in FIG.

In the example shown in FIG. 8, the pulse interval t is read m times and the average value is used as the actual pulse interval t to perform the same control as described above, and blocks 71 and 72 are inserted between blocks 75 and 59. block 67
Then, in blocks 56 to 58, as described above, it is determined whether the number of readings n at the reading pulse interval t satisfies 1<n≦m, that is, whether this number of readings has not reached the specified number m, and it is determined whether the number of readings has not reached the specified number m. If not, control proceeds to block 68, where the number of reads is sequentially counted up from n=1. Then, when the number of readings n reaches the specified number m, the block 67 selects the block 56, and further reading is temporarily interrupted here. Then, while reading the pulse interval, the n-th read value t _o is temporarily stored in the RAM 41 as t in block 69.
By setting n=n+1 in blocks 75 and 76, the read values t ₁ to t _n are sequentially stored in the RAM 41. During this time, in block 71, if the number of readings n has not reached the specified number m, duty maintenance is executed in block 63, and if it has reached the predetermined number m, control proceeds to block 72. In block 72, as described above, the average of the pulse intervals t ₁ ...t _n read a specified number of times is calculated, and the calculation result is set as t, and control of the direct coupling clutch 2 is executed in the same manner as in the example described above, and the same purpose is achieved. can be reached.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional side view of a lock-up torque converter to be controlled by the method of the present invention, FIG. FIG. 4 is a block diagram of a microcomputer used to carry out the method of the present invention, FIG. 5 is a flowchart showing a control program for the microcomputer, and FIG.
The figure is an explanatory diagram of the operating state of the lock-up torque converter, Figure 7 is a table showing the optimum output shaft torque for each prime mover operating state, and Figure 8 is a flowchart showing another example of the control program of the microcomputer shown in Figure 4. It's a chat. 1...torque converter, 2...direct clutch, 4
...Converter cover, 6...Motor rotating shaft, 8...Turbine hub, 9...Output shaft, 10...Shaft hub,
13... Fixed sleeve, 24... Lock-up clutch piston, 25... Converter chamber, 26... Lock-up chamber, 28... Torsion spring, 30...
Lock-up control valve, 35... Lock-up solenoid, 36, 37... Permanent magnet, 38... Reed switch, 39... Central processing unit, 40... Read-only memory, 41... Random access memory, 42...
Input/output interface circuit, 43...engine rotation speed sensor, 44...gear position sensor, 45...throttle sensor.

Claims (1)

[Claims] 1 It has both a transmission path that transmits power from the prime mover to the output shaft via a torque converter and a transmission path that directly transmits the power from the prime mover to the output shaft via a directly coupled clutch connected as appropriate, and prevents slippage of the directly coupled clutch as appropriate. In a lock-up torque converter capable of performing slip control by coupling, the transmission torque to the output shaft is detected, a target output shaft torque is set from the operating state of the prime mover, and the transmission torque is controlled during the slip control. A slip control method for a lock-up torque converter, characterized in that the direct coupling clutch is connected and controlled so that the torque transmitted to the output shaft becomes the set output shaft torque while the rate of change is greater than or equal to a set rate.