JPH0452720B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an electromagnetic clutch provided between a vehicle engine and a transmission.

Generally, there are vehicle clutches that use magnetic particle electromagnetic clutches to automate the clutch operation using the clutch pedal when changing gears or starting the vehicle. The excitation current of the electromagnetic clutch is cut off by the speed change signal, disconnecting the engine from the transmission, and the electromagnetic clutch is connected when the speed change operation is completed. Furthermore, the electromagnetic clutch is de-energized when the accelerator pedal is released, but when the accelerator pedal is depressed, the excitation current is controlled in accordance with the engine rotational speed, allowing a smooth start of the vehicle. Furthermore, the vehicle speed is the set value at which the electromagnetic clutch is directly connected to the transmission, that is, the speed at which it is fully energized. For example, at speeds above 20 km/h, the clutch is fully energized regardless of the engine speed when the accelerator pedal position is changed, making it possible to apply engine braking even when the accelerator pedal is released when the vehicle is decelerating, and also when driving normally. This also prevents clutch slippage, eliminates transmission loss, and reduces clutch heat generation.

In other words, with conventional electromagnetic clutches, the clutch is fully energized, regardless of the accelerator pedal position or engine speed, when the vehicle is running at a predetermined vehicle speed or higher (which can be said to be almost normal driving) where the clutch is directly connected to the transmission. Transmission torque greater than the maximum torque required for vehicle running is always generated. However, when the accelerator pedal is released during normal driving, it is not necessary to fully excite the electromagnetic clutch; it is sufficient to generate only the transmission torque equivalent to the engine braking torque, and a considerable amount of excitation current is wasted. It had the disadvantage of being For example, if the accelerator pedal is released when driving downhill, the excitation current of the electromagnetic clutch is set to zero when the vehicle speed is below a predetermined value, so the engine brake will not act on the vehicle and the vehicle will move downhill. When the vehicle is sequentially accelerated and reaches a predetermined speed, the electromagnetic clutch is suddenly fully energized and the engine brake is suddenly applied, causing a large shock to the vehicle and causing discomfort to the driver.

The present invention has been made to eliminate the above-mentioned drawbacks, and the present invention classifies the running state of the vehicle into four types depending on whether the accelerator pedal is released or depressed and whether the vehicle speed is higher than a predetermined vehicle speed. By setting the excitation current characteristics of the electromagnetic clutch according to the engine speed according to the state, the electromagnetic clutch is controlled with the optimum excitation current according to the driving state of the vehicle. It is an object of the present invention to provide a control device for an electromagnetic clutch for a vehicle, which reduces current consumption of the electromagnetic clutch and allows comfortable driving at all times in any driving condition.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an excitation coil of a magnetic particle type electromagnetic clutch provided between an engine and a transmission of an automobile, to which a power supply voltage of an on-vehicle battery 2 is applied. 3 is an output transistor that is connected in series to the power supply circuit of the excitation coil 1 and performs a switching operation; 4 and 5 are commutation circuits that release the electromagnetic energy of the excitation coil 1 with a predetermined time constant when the output transistor 3 is off; The electromagnetic clutch consists of a diode and a resistor, and a coupling torque is generated approximately in proportion to the current value of the exciting coil 1. 6 is a resistor for detecting the current flowing through the excitation coil 1 as a voltage, even during commutation; 7 is an operational amplifier that constitutes a non-inverting amplifier circuit together with resistors 8 to 10; this amplifier circuit detects the voltage across the resistor 6; amplify. Reference numeral 11 denotes a comparator, which receives the output voltage of the amplifier circuit into its inverting input terminal, compares this voltage with the voltage applied to its non-inverting input terminal, and operates according to the result.
Outputs a high or low signal. resistance 1
Reference numerals 2 and 13 provide positive feedback of the output of the comparator 11 to the non-inverting input terminal by a voltage determined by the resistance ratio to provide hysteresis in the magnitude comparison level. 15 is a transistor that performs switching operation according to the output of the comparator 11, and resistors 16 to 1
Together with 8, they constitute an amplifier circuit that turns on and off the output transistor 3.

On the other hand, 19 is an engine rotation signal generator that generates pulses at a frequency corresponding to the engine rotation speed, and generates, for example, a primary voltage pulse of the ignition coil that is generated in synchronization with the ignition spark. Reference numeral 20 denotes a speed signal generator for the vehicle, which is specifically formed by a rotation sensor that generates a pulse signal with a frequency proportional to the rotation speed of the output shaft of the transmission. 21 is an accelerator switch that outputs a reversal signal in response to release or depression of the accelerator pedal, and 22 is a shift switch that outputs a signal when the transmission is shifting. 23 receives output signals from the engine rotation signal generator 19, the vehicle speed signal generator 20, the accelerator switch 21, and the shift switch 22, and sequentially calculates the engine rotation speed Ne and vehicle speed Vw, and calculates the engine rotation speed Ne and vehicle speed Vw in advance according to the running condition of the vehicle. It is a calculation device that generates a digital output signal according to the excitation current value of the excitation coil 1, and is an electronic circuit including a digital microcomputer. 24 is a digital-to-analog (D/A) converter;
The digital output is converted into an analog voltage and inputted to the non-inverting input terminal of the comparator 11 via the resistor 14.

Next, the operation of the above device will be explained using FIGS. 2 and 3. The engine speed Ne is calculated inside the arithmetic unit 23 for each signal input based on the time interval of the signal input from the rotation signal generator 19, and the vehicle speed Vw is also calculated by receiving the signal from the vehicle speed signal generator 20. Similar to the calculation of the engine rotation speed Ne, the calculations are performed one after another, and the respective results are stored in the storage means inside the arithmetic unit 23. On the other hand, the outputs of the accelerator switch 21 and shift switch 22 are input to the arithmetic unit 23 at sufficiently short intervals (for example, 5 msec).
The arithmetic unit 23 combines the data of the engine speed, the accelerator switch 21, and the vehicle speed Vw into a second
Sequentially (for example, every 5 msec) to which region it belongs among the four running states (modes) shown in the figure.
Then, select one of the four characteristic lines in Figure 3 (described in detail later) that correspond to each of the modes a to d in Figure 2, and set the engine speed at that time. The excitation current value corresponding to the current value is output to the D/A converter 24 as digital data. D/A converter 2
4 converts this digital data into an analog voltage, and this output voltage is divided by resistors 12 and 14 and applied to the non-inverting input terminal of the comparator 11. The circuit after the comparator 11 is a current control circuit configured to supply a current proportional to the set voltage applied to the non-inverting input terminal of the comparator 11 to the exciting coil 1. That is, as described above, the current flowing through the exciting coil 1 is detected as a voltage across the resistor 6, including during its commutation period, and this voltage is linearly amplified by a predetermined factor using an operational amplifier 7 or the like.
When this amplified voltage is larger than the set voltage, transistor 15 and transistor 3 are turned off, and the coil current decreases through the commutation circuit. Conversely, when it is smaller, transistors 15 and 3 are turned on, and current is supplied from battery 2. operates in such a way that it increases. In this current control, in particular, the transistor 3, which directly drives the coil current, is switched on or off so as to reduce its power consumption as much as possible, and the control mode of the electromagnetic clutch is determined based on the vehicle speed signal. However, since the accuracy of the vehicle speed signal generator 20 is not very good, an appropriate hysteresis is provided in the comparison level of the comparator 11 as described above in order to prevent the clutch control mode from being erroneously determined due to fluctuations in the vehicle speed signal. .

Next, regarding the setting of the excitation current of the electromagnetic clutch,
This will be explained in detail using FIGS. 2 and 3. Modes a to d in Fig. 2 change the running state of the vehicle to 4
The curves correspond to characteristic lines a to d in FIG. 3, respectively. Characteristic lines a to d are characteristic curves of the excitation current of the electromagnetic clutch with respect to the engine speed Ne, and are stored in advance in the internal storage means (semiconductor memory) of the arithmetic unit 23. -d is selected.

First, mode a in Fig. 2 corresponds to a state in which the accelerator is depressed and the vehicle speed is less than a predetermined vehicle speed (20 km/h in the example) that directly connects the electromagnetic clutch to the transmission, that is, when the vehicle starts, and the electromagnetic clutch is excited at this time. The current is controlled based on characteristic line a in FIG. Characteristic line a is set so that when the engine speed is low, the driving torque generated by the engine is larger than the coupling torque of the electromagnetic clutch, and as the engine speed increases, the coupling torque of the electromagnetic clutch is gradually increased. It is set to increase in size. Therefore, in mode a, when the driving torque generated by the engine is greater than the coupling torque of the electromagnetic clutch, the clutch slips, which is a so-called half-clutch state, and as the engine speed increases, the coupling torque of the electromagnetic clutch gradually increases. This allows for a smooth starting operation.

Mode b in FIG. 2 corresponds to a state in which the accelerator is depressed and the vehicle speed is higher than a predetermined vehicle speed (20 km/h in the embodiment) that directly connects the electromagnetic clutch to the transmission, that is, a normal running state. Characteristic line b in Figure 3, which corresponds to mode b, is set to correspond to the characteristic curve of the driving torque generated by the engine when the throttle valve is fully open, and the connecting torque of the electromagnetic clutch is defeated by the driving torque generated by the engine. It is set so that no slipping occurs. Therefore, in this mode b state, the electromagnetic clutch generates sufficient coupling torque, and the engine and transmission are directly coupled without slipping.

Mode d in Figure 2 corresponds to a state in which the accelerator pedal is released and the vehicle speed is above a predetermined vehicle speed (20 km/h), that is, a state in which the accelerator pedal is released in normal driving conditions (mode b), and at this time the engine acts as a brake. . In this state, it is only necessary to apply an engine brake to the vehicle corresponding to the engine speed at that time, so it is necessary and sufficient for the clutch to generate a coupling torque capable of transmitting the engine brake torque. Therefore, the characteristic line d in Fig. 3 is a characteristic that provides an excitation current that is approximately proportional to the engine speed and generates a coupling torque corresponding to the engine braking torque, that is, the relationship between the engine speed and the throttle valve when the throttle valve is fully closed. The characteristics are set to generate a coupling torque that is slightly larger than the engine braking torque, which is approximately proportional to the difference between the no-load engine rotation speed NO, and the coupling torque is generated in an amount necessary and sufficient to transmit the engine braking torque mentioned above. is set to occur. In other words, in the conventional device, when the vehicle speed exceeds a predetermined value, the electromagnetic clutch is fully excited regardless of the accelerator state or the engine speed, but with the present invention, the electromagnetic clutch is fully excited when the vehicle speed exceeds a predetermined value. By applying only a small amount of excitation current, the current consumption of the electromagnetic clutch is significantly reduced.

Mode c in FIG. 2 corresponds to a state in which the accelerator is released and the vehicle speed is less than a predetermined vehicle speed (20 km/h in the embodiment), that is, the engine acts as a brake and is at an extremely low speed. Characteristic line c in Fig. 3, which corresponds to mode c, is set slightly smaller than characteristic line d above, so that the engine speed can be adjusted to generate a small coupling torque corresponding to the engine speed while preventing engine stalling. The characteristics are set to provide a nearly proportional excitation current. That is, according to the characteristic line c, it is possible to obtain a coupling torque that is necessary and sufficient to transmit the necessary engine braking torque at extremely low speeds, and is not so large as to cause the engine to stall. Therefore, mode c prevents the engine from stalling due to a sudden stop, and enables engine braking up to extremely low speeds. Furthermore, when starting on a downhill slope with the accelerator released, engine braking torque is initially applied according to characteristic line c,
When the vehicle reaches a predetermined speed (20 km/h), engine braking torque is applied according to the characteristic line d, so unlike conventional methods, sudden engine braking is applied as soon as the vehicle speed reaches a predetermined speed. This will not cause any discomfort to the driver.

Although the operation of the transmission was not explained in the above operation explanation, in the case of a manual transmission that cannot be continuously operated, when a gear shift operation is performed, the electromagnetic clutch is de-energized and the engine and transmission are connected. The control to open the connections between them is the same as in the past.

As described above, in the present invention, the electromagnetic clutch, which is disposed between the engine and the transmission of the vehicle and whose transmission power can be changed depending on the magnitude of the excitation current, is used to control the movement of the vehicle depending on the accelerator operation and the vehicle speed. It goes without saying that by determining the state and controlling the magnitude of the excitation current by comparing the engine speed with the excitation current characteristic curve corresponding to the determined driving state, it is possible to automate vehicle starting and clutch operation during normal driving. This makes it possible to apply engine braking to extremely low speeds, and also to reduce the impact caused by engine braking when driving downhill.
Furthermore, it is possible to realize a control device for an electromagnetic clutch for a vehicle, which makes it possible to reduce the consumption of excitation current to a sufficient amount. Furthermore, the control mode of the electromagnetic clutch is changed depending on whether the vehicle speed is above or below a predetermined vehicle speed, but since there is a large error in the vehicle speed signal, erroneous determination of the control mode can be prevented by providing hysteresis to this predetermined vehicle speed. .

[Brief explanation of the drawing]

Fig. 1 is an electrical configuration diagram of the device of the present invention, Fig. 2 is a diagram showing four running states that are classified for control purposes in the device of the present invention, and Fig. 3 is a diagram showing settings corresponding to each running state in the device of the present invention. FIG. 3 is a characteristic diagram of the excitation current of the electromagnetic clutch. 1... Excitation coil, 3... Output transistor,
7... operational amplifier, 11... comparator, 19
... Engine rotation signal generator, 20 ... Vehicle speed signal generator, 21 ... Accelerator switch, 22 ... Shift switch, 23 ... Arithmetic device, 24 ... D/
A converter.

Claims (1)

[Claims] 1. Disposed between the engine and transmission of a vehicle,
A magnetic particle type electromagnetic clutch that generates a coupling torque approximately proportional to the excitation current supplied to the excitation coil, a vehicle speed detection means that detects the speed of the vehicle, an engine rotation speed detection means that detects the engine rotation speed, and an accelerator. accelerator state detection means for detecting whether the pedal is depressed or released; vehicle speed determination means for determining whether the vehicle speed detected by the vehicle speed detection means has reached a predetermined vehicle speed or higher for connecting the electromagnetic clutch; Based on the outputs of the vehicle speed determining means and the accelerator state detecting means, it is determined that when the accelerator is depressed, the first
a second mode in which the vehicle speed is above a predetermined speed when the accelerator is depressed; a third mode in which the vehicle speed is below the predetermined speed when the accelerator is released; and a fourth mode in which the vehicle speed is above the predetermined speed when the accelerator is released; First, second, third, and fourth current characteristics for determining the excitation current value of the electromagnetic clutch are set and stored in correspondence with the fourth mode, and at least the fourth current characteristic is determined based on the engine braking torque. The third current characteristic is set to provide an excitation current approximately proportional to the engine speed so as to generate a corresponding coupling torque, and the third current characteristic is set to generate a small coupling torque corresponding to the engine rotation speed while preventing engine stalling. a storage means that is set to have a characteristic that provides an excitation current that is approximately proportional to the engine rotational speed, and outputs a current value signal in accordance with the corresponding current characteristic by the discrimination means and the engine rotational speed detection means; A control device for an electromagnetic clutch for a vehicle, comprising a control circuit for controlling an excitation current of the electromagnetic clutch according to an output of the electromagnetic clutch. 2. The control device for an electromagnetic clutch for a vehicle according to claim 1, wherein the determination reference value of the vehicle speed determination means is set with a predetermined amount of hysteresis.