FR2668617A1 - Method and device for controlling an electric motor of a seat, especially a vehicle seat, which is motor-actuated - Google Patents

Abstract

The invention relates to a method for controlling an electric motor of a seat, especially a vehicle seat, which is motor-actuated, in which method a current position and a stored position of a mobile element of the seat are determined by metering (counting), as is the distance which separates them, in such a way that, when the said mobile element approaches the stored position, the speed of rotation of the motor diminishes gradually and the mobile element stops gently in the said position. <??>The invention also relates to a device intended for applying this method.

Description

4 2668617

Method and device for controlling an electric motor of a seat.

The present invention relates to an electric motor control device for a motor vehicle seat, powered by a motor, and more particularly to a method and a device for controlling the motor of this type of seat with a view to enabling an adjustment of movable elements associated with a device for adjusting the driving position. There is a motor-driven motor vehicle seat which has a memory system for memorizing a position of associated moving parts of a driving position adjuster, called a memorized position, so that the parts can pass. at any time and repeatedly from a current position to a memorized position These two positions are determined by a certain number of rotations of a motor provided in the seat, and the system compares the number of valid motor rotations respectively for the current position and the memorized position, in order to limit the range

movement of the driving position adjuster.

According to an existing system of this type, the displacement of the driving position adjusting device ceases when the counted number of rotations of the engine reaches the number corresponding to that of.

the memorized position, by activating a switch.

However, the device is stopped so abruptly that it causes shock to the occupant of the seat and psychological discomfort, and slippage of the moving parts of the device occurs due to an inertia force produced during its movement. which results in less precision in the positioning of the elements.This sliding also causes a slight difference between the value of the counter and the practical position of the elements, and over a long period of repetition of the sliding, these small differences accumulate up to constitute

a significant difference between the current position and the memorized position.

In this case, it is certainly possible to provide compensation means and a

computer, but this involves high costs and complicated assembly.

In addition, a conventional system of this type only has a moderate speed for moving the associated moving parts, which poses a problem in that the parts cannot be moved or quickly over the long travel path, nor can they be moved quickly along the long travel path. slowly for precise adjustment of positions using a manual control switch. In view of the aforementioned drawbacks, the object of the present invention is to provide a method and a device for controlling an electric motor in a motor-driven vehicle seat, which make it possible to stop a movable element of a control device.

riding position adjustment without shock or slippage.

To this end, provision is made, according to the invention, for the movable element of the driving position adjustment device to be moved between the position of the moment and the position stored by means of a motor so that , when said movable element reaches, at a given stopping point, a certain point of the distance between the two positions, a voltage applied to the motor is gradually reduced by a voltage control circuit so that the movable element is displaced and smoothly shut down The voltage control circuit is designed to provide a time constant to delay the shutdown or release of voltage to make the motor relatively stopping.

slow or moderate.

As a result, the moving element is stopped smoothly, without

shock or slip.

According to one aspect of the invention, in automatic control mode, with the aid of a memory switch, the movable element is moved rapidly to the memorized position, and in manual control mode, with the aid of a memory switch, the element is moved slowly to a given position, which allows precise adjustment of the position of the element at a desired point The motor is therefore suitable for being controlled with a view to changing its rotational speed, depending

of the conditions of the moving element.

The above and other purposes, advantages and features

of the present invention will emerge more clearly from the description

following detailed description of a preferred embodiment thereof, given by way of non-limiting example with reference to the appended drawings in which: FIG. 1 is a block diagram which schematically shows an electrical interconnection in a control device of an electric motor according to the present invention; Figure 2 is a block diagram which schematically shows an electrical connection between said device and a movable member in a motor-operated seat; Figure 3 is an electrical circuit diagram of a voltage control circuit and a brake circuit; and Figures 4 and 5 are timing tables of signals and pulses, which show the electrical operations which take place in the electric motor controller, respectively for

high and low voltage control signals.

Figures 1 to 5 show a more preferred embodiment of an electric motor control device used in a motor vehicle powered seat, generally designated by reference numeral 10 and comprising a motor 12, a switch. manual 14, a memory switch 16, a central processing unit 18, a voltage control circuit 20, a circuit

brake 22 and relays 44, 44 a, 45, 45 a.

The motor 12 has a position detector 13; it is preferably a direct current motor As can be seen in figure 2, it is designed to actuate a seat sliding device 26 which, in this embodiment, constitutes the position adjustment device driving subject to the control device 10 The normal and reverse drives of the motor 12 respectively advance and reverse the sliding device 26 and, thereby, a seat 24 mounted thereon. A sliding device 26 of this type does not is not limiting, in the invention, but other types of devices

driving position adjustment can be applied.

The position detector 13 used is a rotation detector which comprises a disk-shaped magnet 28 and a conductive switch 30 adjacent to the previous one, the magnet 23 being connected to an output shaft of the motor 12 The rotation detector 13 emits several pulses for each rotation of the output shaft of the motor 12 As seen in Figure 1, the conductive switch 30 is connected to the central processing unit 18, referred to as the "CPU", which enables the 'access to this one of the pulses when they are emitted, in which case the CPU 18 counts the number of pulses When the motor 12 is driven in a normal direction, the number of pulses increases, while, when the motor 12 is driven in the opposite direction, the number

of pulses decreases.

As shown in Figure 2, the manual switch 14 and memory switch 16 are disposed on an armrest 34 integral with the inner wall of a front door 32. The manual switch 14, as seen in Figure 1 , is a DC "rocker type, self-returning, neutral off position and two on positions, and connected to the CPU 18 The switch 14 is intended to control the motor 12 through the switch. CPU 18 in order to adjust the back and forth movement of the sliding device 26 and thereby adjust the position

front and rear of seat 24.

The memory switch 16 is a push-button switch 36 of the self-return type comprising a setting switch 36 and a

memory call switch 38, connected to the CPU 18.

In this context, with the seat placed at an arbitrary point, if the setting switch 36 is actuated, the CPU 18, in response, stores the number of pulses from the rotation detector 13 in memory.

co Tnme seat memory position 24.

Then, upon actuation of the memory call switch 38, the motor 12 is started through the CPU 18 to automatically move the seat 24 to the position.

memorized and pre-set.

The CPU 18 includes a microcomputer 40; it processes input signals according to a given program Tmne and outputs an appropriate control signal which activates one of the first and second relays 44, 44 a, 45, 45 a to cause the motor 12 to be driven. The CPU 18 counts pulses from the rotation detector 13 and determines the

moment position of the seat 25 by a number of counted pulses.

The count numbers of the current position and the stored position are mutually matched by the CPU 18 so that, under the effect of actuation of the memory call switch 38, the seat is moved to the stored position. when the count number of the

position of the moment is equal to that of the memorized position.

The range of movement of the seat sliding device is limited by means of two limit switches 46 which are shown in figure 1 in the form of push-buttons with automatic return. One of them is intended to limit the forward movement. of

device 26 and the second is intended to limit its rearward movement.

The two limit switches 46 are connected to the CPU 18.

Also provided in the controller 10, as shown in Fig. 1, an overload current detection circuit 48 and an overload current detection resistor 47 which cooperate to detect an overload current due to an overload condition. of the motor 12 and whereby the CPU 18 sends a stop signal to the motor 12, abruptly interrupting the drive thereof and eliminating current overload as well as the resulting overheating or overheating.

engine degradation 12.

Reference numeral 49 denotes a battery which serves as a

power source for control device 10.

Figure 3 gives the details of the voltage control circuit

20 and the brake circuit 22.

The 20 DC voltage command dc circuit consists of a first switch-type integrated circuit (IC) IC 1-1 and a second IC 1-2 The first IC is activated from a high voltage control signal Hi produced at the Using the memory switch 16 to allow a high voltage to flow through the circuit, while the second IC is activated from a low voltage control signal Lo produced using the manual switch 14 As it is shown in the figure, the high and low voltage control signals Hi, Lo are input from the respective power lines 50, 52 into the ICs

respective IC 1-1, IC 1-2.

When the high voltage control signal Hi of a high voltage is input to the first IC 1-1, a voltage from the power source 49 is transformed by a first Zener diode ZD 1 into a given constant high voltage, and transmitted to a differential operational amplifier IC 2 ccm carrying two transistors Trl, Tr 2 and three resistors R 3, R 4, R 5 electrically connected to these, as it is shown Then the amplifier IC 2 aplifies in a constant manner

the voltage up to a predetermined high voltage 1, which in turn outputs

even from circuit 20, passes through an electric line 54 having a diode Dl in the brake circuit 22, and passes through one of the first and second relays 44, 44a, 45, 45a, which results in application of the high voltage to the motor 12 and the

the latter at a high rotational speed.

Likewise, when the low voltage control signal Lo is input to the second Ie 1-2, a given constant low voltage is produced by a second Zener diode ZD 1 and continuously transformed by amplifier 1 C 2 at a predetermined low voltage The voltage is brought through the intermediary of the braking circuit 22 and the relays 44, 44 a, 45, 45 a to the motor, causing the drive to

the latter at a low speed of rotation.

Accordingly, it is seen that the actuation of the manual switch 14 causes the motor 12 to rotate slowly for slow movement of the sliding device 26, so that the position of the seat 24 can be precisely adjusted and safe, and that the seat 24 per se can be stopped with precision at a desired point, while the actuation of the memory switch 16, more precisely of the memory call switch 38, causes the motor 12 to rotate rapidly in view. a rapid movement of said device 26, which causes

the immediate displacement of the seat 24 to the memorized position.

The braking circuit 22 as shown in FIG. 3 is interposed, on an electric line, between the voltage control circuit 20 and the motor 12 As indicated, the circuit 22 detects an electromotive counter-force created in the motor. motor 12 in

works and uses it as the regenerative braking associated with it.

In other words, if, for example, a voltage applied to motor 12 from voltage control circuit 20 becomes lower than such a voltage and the electromotive counter force of motor 12 becomes higher than said voltage, this passes through one of the relays 44 a, 45 a, the transistor Tr 3, the resistor RT and the line 56 of the circuit

brake 22, then is returned to the motor 12 As a result, the counter

electromotive force thus reduced is transformed into braking torque

of the motor 12 which reduces the speed of rotation thereof.

In the braking circuit 22, the desré of the braking torque

can be adjusted by varying the value of the RT resistor.

According to the control device 10, it is preferably provided that a stopping point is defined at 75% of the amplitude of displacement of the seat sliding device 26, that is to say of the distance between the current position and the stored position Thus, when seat 24 reaches this 75% point, the CPU 18 blocks the high or low voltage control signal Hi, Lo to interrupt a flow of

current to motor 12.

With respect to the voltage control circuit 20, the timing of the start of application of a voltage to the motor 12 is adjustably delayed by the variation of a time constant which is determined from the fixed value of resistance R 1 and capacitor 00, or that of resistor R 2 and capacitor 00, so that the applied voltage reaches a fixed normal value in a given duration, and the motor 12 thus starts running slowly or moderately to its initial drive position This applies to both high and low voltage signals Hi, Lo In addition, the moment of stopping the application of voltage can also be adjustably delayed by varying d 'a time constant which is determined by a value of the resistor RO and the capacitor OO so that when the high and low voltage control signals Hi, Lo are blocked, the voltage supply does not take place, but that a voltage retained in the capacitor CO is slowly released from it according to a value defined by a time constant of the resistance RO and the capacitor CO, which has the effect of gradually reducing the speed of rotation of the motor and putting it thus

gradually to stop.

Figures 4 and 5 help to understand the control of motor 12,

described above, in the device 10 of the present invention.

According to the chronological table of FIG. 4, it can be seen that, when the memory call switch 38 is actuated, the high voltage control signal Hi is sent to the voltage control circuit 20, the relays 44, 45 being energized to establish an adequate relay contact at 42 a, 44, and the start of the application of high voltage to the motor 12 is postponed to a given moment, according to a determined value of the resistance R 1 and of the capacitor 00 C, as it has been indicated above Consequently, the motor 12 starts up slowly or moderately, and pulses are produced at the same time from the rotation detector 13 These pulses must be counted as

that the amplitude of displacement of the c Julissement device 26, that is

say the range of movement of the seat 24.

Then, when the applied voltage reaches a fixed normal value of high voltage, the motor 12 is forced to rotate at a speed of

high rotation, thus moving the seat 24 quickly.

After that, when the slider 26 moves the seat 23 from the current position to the above-mentioned 75% stop position, towards the stored position, the CPU 18 blocks the high voltage command signal. Hi, ceasing to apply the high voltage to the motor 12 A that name, the voltage retained in the capacitor CO is released moderately in cooperation with the resistor RO, following a value corresponding to the time constant mentioned above, and accordingly , the gradual decrease in

the voltage lowers the rotational speed of the motor 12.

Then, when the number of pulses counted is equal to that which is memorized for the memorized position, the contact points 44 a, 45 a of the relay 44, 45 go into a normal contact state Consequently, the voltage is not not applied to motor 12 and seat 24 is immediately stopped, no pulse being emitted from rotation detector 13 and no braking torque being produced from brake circuit 22 At this time, this modification of

contact points of relays 44 a, 45 a short-circuit to

screw of the motor 12, hence the creation in the motor 12 of a stopping torque which has a regenerative braking effect. By virtue of this holding torque, the motor 12 is effectively maintained in a stopped state and the seat 24 is placed securely in a given position even

when the motor 12 is not activated.

The aforementioned electrical steps also take place in cases where the low voltage tnand DC signal Lo is input to the second switch IC 101-2 of the voltage control circuit In this case, the difference from a signal Hi voltage control command is that the applied voltage is low voltage and therefore motor 12 rotates at a low rotational speed The figure is obvious enough to make it clear how low voltage is applied to motor 12, and the steps are the same as on

figure 4.

Accordingly, for the above description, it should be noted

that the motor 12 is not stopped suddenly, unlike the prior art mentioned above Its speed of rotation is on the contrary reduced until it stops, which prevents excessive displacement of the sliding device 26 and a sliding of its movable elements, and avoids any difference in counting number between the position of the

moment and memorized position.

Although the foregoing description has focused on a mode of

preferred embodiment of the present invention, it is understood that this

This is not limited to the example described and illustrated here, and those skilled in the art will easily understand that it is possible to make various other changes and modifications to it without departing from the scope of the invention For example, the engine control device 10 and the associated control method can be applied to other types of driving position adjustment devices such as reclining device, headrest, seat lifting device, a lateral support device or the like, and any other kind of seat For the automatic control mode by means of the memory call switch 38 and the manual control mode by means of the manual switch 14, a two-way selection mechanism speeds may be provided to cause the motor 12 to rotate at the desired speed, based on the timing device, described above, for applying voltage to the motor 12, so that the motor 12 can be started quickly to move the driving position adjuster, and therefore the seat 23, over a long

distance separating the current position and the menmorised position.

Claims (9)

1 A method for controlling an electric motor of a motor-operated vehicle seat, wherein a movable member of a driving position adjuster is to be moved between a position of the moment, in which said movable member is at a arbitrary point, and a memorized position, in which said element can be stored in a desired point, and this thanks to the control of the motor (12), and in which said movable element is automatically reset to said memorized position by an operation memory call, characterized in that it comprises the steps of counting said memorized position and storing the corresponding number in a memory; counting the distance between the memorized position thus counted and said current position, in order to determine the location of said memorized position and the current position; defining a stop position at a predetermined point over said distance separating the current position and the stored position; causing that when said movable member reaches said stop position, the voltage applied to the motor (12) gradually decreases and that some braking action is exerted on said motor (12), thereby reducing the rotational speed of this one; and stopping said motor (12) when the movable member reaches said stored position, so to immobilize said movable element in this position. 2 Method according to claim 1, characterized in that it comprises the steps of detecting a position of said movable element using pulses produced from a rotation detector (13) provided for said motor (12) , and capturing said stored position and said current position using said pulses, so as to determine said distance separating the two positions. 3 Method according to claim 1, characterized in that said braking action is exerted by a regenerative braking method which produces an electromotive counter-force in the motor (12) when the applied voltage decreases, in order to promote the decrease in engine rotation speed (12). 4 A method according to claim 1, characterized in that it carries the steps of controlling said voltage under given conditions, in order to allow the motor (12) to be selectively changed from a fast rotational speed to a rotational speed. slow. A method according to claim 1, characterized in that it comprises the steps of controlling said voltage under given conditions, in order to allow the motor (12) to be selectively changed from a high rotational speed to a low rotational speed ; allow manual control mode using a manual switch; causing the motor (12), in this manual control mode, to run at said slow speed; allow an automatic control mode using a memory call switch adapted to call the stored position; and bring the motor (12), in this mode of automatic control, to rotate at said rapid speed. 6 The method of claim 1, characterized in that it includes the steps of controlling said voltage under given conditions to allow the motor (12) to be selectively changed from a high rotational speed to a low rotational speed. ; allow a manual control mode using a stored position; causing the motor (12), in this manual control mode, to run at said slow speed; allow an automatic control mode using a memory call switch adapted to call the stored position; and allowing, in this automatic control mode, to selectively change the motor (12) from a fast rotational speed to a slow rotational speed, depending on the distance over which said movable member of the device is to be moved. driving position adjustment device. 7 The method of claim 1, characterized in that it also comprises the steps of delaying a moment of start of application of said voltage to the motor (12), which makes the initial drive of the motor (12) relatively slow , and to delay the moment of stopping the application of the voltage, which makes the decrease the speed of rotation of the motor (12) fairly progressive. 8 Device (10) for controlling an electric motor of a motor-driven vehicle seat, characterized in that it comprises a motor (12) for causing the movement of a movable element of a position adjusting device of conduit provided in said seat (24) position detecting means (13) for detecting a position of said movable member; a manual switch (14) for controlling the drive of the motor (12) to adjust said position of the movable member; a memory switch (16) for storing a position of the mobile element, which becomes the memorized position, and call this ci in order to automatically return the movable element to the memorized position; a central processing unit (18) connected to the motor (12), to the position sensing means (13), to the manual switch (14) and to the memory switch (16), said central processing unit (18) processing the data according to a predetermined program to control the driving of the motor (12); a voltage control circuit (20) for controlling a voltage applied to the motor (12), said voltage control circuit (20) changing the motor (12) to a desired rotational speed under certain conditions; and a braking circuit (22) for exerting a braking action against the motor (12); in that there is a predetermined distance between the current position and the stored position of the movable member, and in that when the movable member reaches a defined stop position at a certain point from said distance, the rotational speed of the motor (12) decreases. 9 Device according to claim 1, characterized in that the position detector means (13) comnport a rotation detector (13) comprising a permanent magnet in the form of a disc (28) fixed to an output shaft of the motor (12) and a conductive switch (30) provided near said magnet (23). Device according to claim 1, characterized in that the voltage control circuit comprises means for determining a time constant making it possible to delay said voltage at an initial moment to apply it to the motor (12) and also at a final moment. to cease the application of voltage to said motor. 11 Device according to claim 10, characterized in that said means comprise an appropriate combination formed of a resistance (RO, R 1, R 2, R 3, R 4, R 5, R 6, R 7, 47) and d 'a capacitor (Co). 12 Device according to claim 1, characterized in that said voltage control circuit (20) comprises a differential operational amplifier (IC 2) comprising a feedback part, which transforms an input voltage into a voltage of one. appropriate level and emits the same in a constant manner, and in that said brake circuit (22) comprises a diode (D 1), a transistor (Tr 3) and a resistance (R 6, R 7) which are arranged so as to produce a counter- electromotive force in the motor (12) in reaction to a change in voltage emitted from the voltage control circuit (20), causing thus a braking torque in the motor (12).