JP2007278463A - Transmission controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress current/voltage variations caused by driving a solenoid and further easily restrain noise generation caused by driving the solenoid. <P>SOLUTION: There is provided a transmission controller 1 equipped with a control means which drives a plurality of the solenoids 2 for transmission control using a plurality of switching elements 6 subjected to on-off control governed by a PWM signal output from a microcomputer 5 and performs over excitation control and chopping control during an on-state of the solenoid. The control means supplies PWM signals 7a, 7b, 7c to each of the switching elements 6 for driving the solenoid 2 with the phases of the PWM signals 7a, 7b, 7c equally displaced by 360°/N resulting from dividing 360°by N, the number of driving circuits of the solenoids and besides performs control of drive so that frequencies for driving the solenoids approximates to an upper limit of audio frequency or exceeds the upper limit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission control apparatus that drives a plurality of solenoids for controlling a transmission of a vehicle by duty control using a plurality of switching elements that are on / off controlled by a PWM (pulse width modulation) signal. It is intended to suppress noise generated from the system power harness.

Various loads in an automobile are driven by a battery as a power source. Therefore, in order to reduce the current consumption of the battery and suppress the heat generation of a load or a driving element such as a semiconductor element (hereinafter also referred to as a switching element), the control of the switching element is performed using a pulse width modulation signal (hereinafter referred to as a microcomputer). A DUTY (duty) control method using a PWM signal is generally used. Also, in order to realize a similar function without using an unnecessarily high-function type microcomputer for the purpose of reducing costs, there is a tendency to limit and use the output (port) of the microcomputer. (For example, refer to Patent Document 1.)
As a result, in the conventional transmission control apparatus using a plurality of solenoids for controlling the hydraulic pressure of the transmission, there are cases in which a plurality of solenoids are driven simultaneously, and the power harness in the automobile is synchronized with the output. A lot of current flows. When this current change is large, noise radiated from the harness of the power supply or drive line becomes large.

FIG. 1 is a schematic configuration diagram of a conventional transmission control device that drives and controls a plurality of solenoids in synchronization with one PWM signal, and FIG. 2 is a schematic diagram of voltage and current waveforms of a power supply line in the conventional device.
In FIG. 1, the transmission control device supplies a controller 1, a plurality of transmission control solenoids 2 connected to the controller 1, a battery 3 as a power source of the solenoid 2, and further supplies a power source of the battery to the solenoid 2. A power supply relay 4 is provided.
The controller 1 includes a microcomputer 5 and a driving element (also referred to as a switching element) 6 that is on / off controlled by a PWM signal from the microcomputer 5 and supplies a driving current from the battery 3 to the solenoid 2 when conducting. Is provided. In addition, 8 is a commutation diode for surge absorption, and 9 is a power supply harness.
In such a conventional apparatus, the plurality of drive elements 6 are on / off controlled by a PWM signal having the same drive cycle from the microcomputer 5, whereby the plurality of solenoids 2 are driven in a synchronized state.
As a result, the voltage and current waveforms of the power supply line from the battery 3 to the solenoid 2 when a plurality of solenoids are driven are as shown in the schematic diagram of FIG. 2, and the current ripple is large.
When the current ripple is large, noise radiated from the harness of the power source or the drive line becomes large, and noise is superimposed on the adjacent radio or harness in a limited space in the automobile.

JP 2001-132865 A

In the control apparatus for a vehicle transmission using a solenoid that is driven and controlled by the PWM signal as described above, the frequency of the PWM signal is usually several tens Hz to several KHz from the viewpoint of suppressing hydraulic fluctuation and the cost of the drive circuit. Set to Since this is the human audible frequency (generally 20 Hz to 20 KHz, but acoustically the upper limit frequency decreases with age and is usually referred to as 12 to 15 KHz) itself, When the noise is directly superimposed on the radio, the harness, or the speaker, there is a problem that it can be heard as extremely annoying noise.
In the case of a conventional transmission control device, as described above, a plurality of solenoids are driven with the same period by one PWM port of the microcomputer, so that the plurality of solenoids operate synchronously,
As a result of the increase in current ripple, radiation noise increases, which is superimposed on nearby radios and speakers as noise and becomes annoying noise.

  In order to reduce noise superimposition on the radio / speaker, a method of reducing the current change is conceivable. However, in the case of solenoid-type transmission control, due to the problem of solenoid responsiveness due to hydraulic control, it is instantaneous in the initial operation. It is necessary to flow a large current to ensure responsiveness and to perform holding control while suppressing the current by subsequent chopping control. It becomes a problem to suppress the current change in all the processes.

Increasing the drive frequency of the solenoid beyond the audible frequency of humans is not easy because there are restrictions due to heat generation problems such as the response of the solenoid itself and the switching loss of the drive element.
In addition, it is difficult to reduce the chopper frequency below the audible frequency from the viewpoint of hydraulic pressure fluctuation.

  The present invention has been made to solve the above-mentioned problems of the conventional apparatus, and the frequency of the PWM signal for driving a plurality of sets of solenoids (for example, 3 sets) is several KHz (for example, 4 KHz). And the phase of each group is shifted from each other, whereby the change in voltage and current is reduced at the change point between each phase of each group by solenoid driving. In addition, by providing an apparent solenoid drive frequency equal to or higher than the audible frequency (for example, 12 kHz), a transmission control device is provided that suppresses the generation of noise and prevents the noise from being heard as noise to a radio or a speaker. The purpose is to do.

  The transmission control apparatus according to the present invention drives a plurality of transmission control solenoids by duty (DUTY) control using a plurality of switching elements that are controlled to be turned on / off by a PWM signal from a microcomputer. In the transmission control apparatus including a control unit that performs excitation control and chopping control, the control unit sets the phase of the PWM control signal supplied to each of the plurality of switching elements for driving the solenoid to 360 °. The same phase difference (360 ° / N) divided by the number N of solenoid drive circuits is shifted to supply each switching element, and the frequency for driving the solenoid is close to or above the upper limit of human audible frequency The drive control is performed so that the frequency becomes.

  According to the transmission control device of the present invention, fluctuations in current and voltage due to driving of the solenoid are suppressed, and generation of noise due to solenoid driving is easily suppressed. As a result, it is possible to suppress noise propagation to the speaker and wiring of the in-vehicle radio.

  Further, if there is no problem in heat generation even if the frequency of the PWM signal for controlling on / off of the switching element is increased, the noise generation frequency is further increased and moved to the vicinity of the upper limit (20 KHz) of the human audible range. Even if radiated noise is superimposed on a radio or a speaker, it is effective in making it difficult to hear the noise.

Embodiment 1 FIG.
Hereinafter, the transmission control apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 3 is a schematic configuration diagram showing a circuit configuration of the transmission control apparatus according to the first embodiment of the present invention, and FIG. 4 shows a voltage of a power supply line when the solenoid is driven in the apparatus of the first embodiment. It is a schematic diagram which shows an example of a current waveform. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.
In FIG. 3, the transmission control device supplies a controller 1, a plurality of solenoids 2 for transmission control connected to the controller 1, a battery 3 as a driving power source of the solenoid 2, and a power supply of the battery 3 to the solenoid 2. A power supply relay 4 is provided.
The controller 1 has a microcomputer 5 that outputs a PWM signal to be described later for on / off control of the plurality of switching elements 6, and is turned on / off by the PWM signal from the microcomputer 5. A switching element (solenoid driving element) 6 constituted by a semiconductor element or the like for supplying a driving current from the battery 3 is provided.
A transmission (not shown) is hydraulically controlled by a plurality of solenoids 2 driven and controlled by the switching element 6.
The switching element 6 is provided with a current commutation circuit by connecting a commutation diode 8 to a power source for the purpose of absorbing a surge generated when the solenoid is driven.
9 is a power supply harness.

Next, a PWM signal input from the microcomputer 5 to the switching element 6 will be described.
As described above, in the conventional control system of FIG. 1, the microcomputer 5 outputs one PWM signal 7 as a clock signal having the same driving cycle to the plurality of solenoid driving elements 6. Since the driving of the plurality of solenoids 2 is synchronized with each other, the current ripple is increased, and noise radiation from the power supply harness 9 is increased.
On the other hand, in the first embodiment of the present invention, the phases of the PWM signals supplied from the microcomputer 5 to the plurality of switching elements 6 are shifted on the microcomputer 5 side, and the PWM signals 7a and 7b having shifted phases are shifted. , 7c are input to the switching element 6 which is a solenoid driving element.
At this time, the angle for shifting the phase of each PWM signal is shifted by an equal phase difference obtained by dividing the angle 360 ° by the number N of solenoids that can control the transmission, that is, 360 ° / N.
That is, for example, when N is three, the phase difference is 360 ° / 3 = 120 °, and the PWM signal A, the PWM signal B, and the PWM signal C having a phase difference of 120 ° with respect to each of the switching elements 6 are used. To enter.
The frequency of the PWM signal for driving a plurality of solenoids (for example, 3 sets) is several KHz.
(For example, 4 kHz).

By setting the phase difference and the frequency of each PWM signal in this way, as shown in the schematic diagram of FIG. 4, it is possible to reduce the change in voltage and current at the change points between the respective phases due to solenoid driving. And noise emission can be reduced.
Further, as a result of shifting the phase of each PWM signal, an apparent current of PWM drive cycle × number of divisions (for example, 4 KHz × 3 = 12 KHz) flows in the harness of the power supply source, and the drive frequency of the power supply line is It can be increased and shifted to the upper limit of human audible frequencies.

Further, when the heat generation of the switching element (solenoid driving element) 6 is not a problem (the heat dissipation process is performed), it is desirable that the output of the PWM signal from the microcomputer to the switching element is shifted to a high frequency as much as possible.
By shifting the frequency of the PWM signal to the high frequency side and shifting the phase, the apparent frequency of the power line can be further increased, and even if radiated noise is superimposed on the radio or speaker, the upper limit of the audible frequency It becomes close to or more than that, and it is not audible to humans. Moreover, if the apparent frequency is high, directivity is strong (straightness is strong), and the area that cannot be heard as radio noise in the passenger compartment increases, so that a further radio noise suppression effect can be obtained.

Normally, this type of transmission control device has about six solenoids. These solenoids can be driven independently, and can be divided into groups of several. May be configured to be driven by a common drive circuit corresponding to the drive.
In the latter case, for example, six solenoids are divided into three groups of two, and three drive circuits are provided corresponding to each group. In the case of such a configuration, the three driving circuits drive each group (that is, two solenoids simultaneously). In this case, the phase of the PWM signal is not shifted for each solenoid, but operates in the same manner as the configuration in which the solenoids are driven independently by shifting for each group.
In addition, when dividing a plurality of solenoids into groups of several, it is possible to prevent the solenoids from being simultaneously turned on and off by making the solenoids that are not simultaneously driven into the same group when controlling the transmission. , Voltage and current fluctuation due to driving can be reduced.
Further, when the phase is shifted, the voltage and current fluctuations caused by driving can be minimized by uniformly shifting the angle of the shift, and noise radiated by the current can be minimized. Divide (360 degrees) by the number of solenoids (or the number of groups when shifting for each group) to determine the angle to shift the phase.

As described above, according to the transmission control apparatus of the first embodiment of the present invention, fluctuations in current and voltage due to driving of the solenoid are suppressed, and generation of noise due to solenoid driving is easily suppressed. Propagation of noise to in-vehicle radio speakers and distribution lines can be suppressed.
Moreover, since the solenoid drive frequency shifts to the vicinity of the upper limit of the human audible range, there is an effect of making it difficult to hear noise even if radiation noise is superimposed on a radio or a speaker.

  Furthermore, since the control frequency of the switching element (solenoid driving element) is not changed, heat generation of the switching element itself can be suppressed.

  The present invention can be used in a transmission control device that drives a plurality of solenoids for vehicle transmission control by duty control using a PWM (pulse width modulation) control method.

It is a schematic block diagram of the conventional transmission control apparatus which drive-controls several solenoids by a PWM control system. It is a schematic diagram which shows an example of the voltage of a power supply line in a conventional apparatus, and a current waveform. It is a schematic block diagram of the transmission control apparatus of Embodiment 1 of this invention. FIG. 4 is a schematic diagram illustrating an example of a voltage and current waveform of a power supply line when driving the solenoid according to the first embodiment.

Explanation of symbols

1 Controller 2 Solenoid 3 Battery 4 Power Relay 5 Microcomputer (Microprocessor)
6 Switching element (solenoid drive element)
7 PWM signal 7a PWM signal A 7b PWM signal B 7c PWM signal C
8 Commutation diode

Claims (1)

  Control means for driving a plurality of solenoids for transmission control by duty (DUTY) control using a plurality of switching elements that are ON / OFF controlled by a PWM signal of a microcomputer, and performing overexcitation control and chopping control while the solenoid is on In the transmission control apparatus provided, the control means equalizes the phase of the PWM signal supplied to each of the plurality of switching elements for driving the solenoid by dividing 360 ° by the number N of drive circuits of the solenoid. The phase difference (360 ° / N) is shifted to be supplied to each switching element, and the drive control is performed so that the frequency for driving the solenoid is close to the upper limit of the human audible frequency or higher than the upper limit. A transmission control device characterized by that.

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