FR2880182A1 - Fluid e.g. compressed air, pressurizing device for air pillow of vehicle seat, has pressure switch with contact unit executing movement to open and close contact for certain distance between tripping positions - Google Patents

Abstract

The device has a pressure duct (16) that integrates a check valve (20) and a pressure switch (18). The switch has an electric contact unit (30) that executes a transfer movement to open and close an electric contact (31) for a certain distance between tripping positions. Lower and upper pressure thresholds formed by the transfer movement are used for switching current supplying motor. The valve and the switch are housed in a same case. An independent claim is also included for a method of controlling a fluid pressurizing device.

Description

Field of the invention

  The present invention relates to a device for putting fluid under pressure, comprising a pump connected to a check valve and a pressure switch, the pressure switch comprising at least one movable electrical contact element, and means for open and close an electrical contact.

  The invention also relates to a method for controlling such a device.

  State of the art DE 198 43 347 A1 discloses a device for monitoring a pressure level for controlling an electric pump. A housing houses a check valve and a pressure switch; it is connected by electrical connections to the electrical machine to be switched such as a pump. The inner volume of the bolivar divided into two zones by a membrane, and a switching unit is in one of the zones. When the membrane is stressed by pressure, it deforms and moves an actuating member of the switching unit against the force of a spring. The actuating member moves a spring-loaded electrical contact member in accordance with the applied pressure and the counter spring force until the moving electrical contact member is pushed against another contact element to establish the electrical contact. The continuous, permanent movement of the actuating member according to the applied pressure opens or closes the electrical contact according to a single defined pressure threshold. If for example the actuator closes the electrical contact, a relay and a control electronics implement the air pump. But as soon as the pressure applied to the diaphragm increases only slightly, the electrical contact opens, but the pump remains in operation for a pre-set time by the control electronics to increase the pressure correspondingly. If the operating time was not used by electronic control of the pump, in this dis-positive, for the slightest pressure variations the pump would be permanently switched on and off which would generate a giant noise and reduce the life of the pump.

  DESCRIPTION AND ADVANTAGES OF THE INVENTION The present invention relates to a device of the above-defined type, characterized in that the movable electrical contact element moves for a variable pressure according to a jump function along a path. travel stroke to open or close the electrical contact.

  The invention also relates to a method of controlling such a pump, this method being characterized in that the electrical contact directly switches the current of the pump motor and the device does not include in particular electronic switching circuit.

  The device and the method according to the invention have the advantage of achieving a lower pressure threshold and a higher pressure threshold by the movement by jumping the electrical contact element and using a single electrical contact. These thresholds are used directly to switch the motor current of the pump. The tilting according to the invention of the electrical contact element makes it possible to dispense with a second other pair of contacts, which makes it possible to manufacture a very economical device for a pneumatic lordosis actuator in a vehicle seat.

  As the electrical contact element switches back and forth between two click positions, it is necessary that the fluid exerts a certain force to close the electrical contact of the electrical circuit or to open it. This force is associated with two different pressure thresholds defining between them an interval during which the pump remains connected.

  Due to the distance separating the two click positions which results from the development by construction of the device, the adjustment stroke of the diaphragm urged in pressure makes it possible to define the two pressure thresholds. If this sufficiently large distance is chosen, a dynamic variation of pressure does not risk triggering an electric switching with switching on and off of the pump. Thanks to the two click positions spaced apart from one another or the detent positions, any additional compensation volume for the pressure switch is avoided, which significantly reduces the size of the device.

  Since the moving contact element is actuated only if, by going beyond a jump function, one click is moved from one position to the other, the means for actuating the electrical contact have a hysteresis which can be used directly to regulate the motor current of the pump. The hysteresis related to the construction corresponds to the two pressure thresholds for starting and stopping the pump.

  Particularly advantageously, the jump movement of the electrical contact element can be achieved by providing a spring element with a switching point and two corresponding click positions.

  According to a variant, the click movement is achieved by jumping the electrical contact element by means of an actuating member which is for example pushed by a piston or membrane against the electrical contact element. The actuating member may have two latching points spaced by a predefined distance so that the actuating member passes through a jump, preferably from a first detent point to the second detent point when that we exceed a certain strength. This corresponds to the jump or snap of the electrical contact element passing from one latching position to the other.

  In order to freely adjust the pressure thresholds for the actuation of the electrical contact, it is possible to associate detent elements with the latching points of the actuating member which will retain, for example, with the aid of spring elements. actuating member at a detent point until a certain pressure threshold or a force is exceeded upwards or downwards. This also makes it possible to modify the duration of the interval and thus control the rhythm of the pump later and in a simple way.

  If the electrical contact is such that it directly switches the current supplying the motor of the pump, it removes a facility with a complicated electronic circuit, for example it will not require any relay switch.

  Preferably, the check valve and the pressure switch are housed in the same housing directly associated advantageously with the pressure connection between the pump and the user. Such a compact construction reduces the size of the device so that it is particularly suitable for applications to a motor vehicle and in particular for use in a vehicle seat.

  Drawings The present invention will be described below in more detail with the aid of exemplary embodiments of the device according to the invention shown in the accompanying drawings, in which: FIG. 1 is a schematic view of a first example; embodiment of an electrical contact element in the form of a spring-click, and FIG. 2 is a schematic view of another embodiment of an actuating member cooperating with detent elements. .

  Description of the embodiments

  Figure 1 shows a device 10 for pressurizing a fluid such as a pneumatic cushion 12 of a vehicle seat. As fluid is used for example compressed air with a pump 14 and supplying the air cushion 12 constituting the user 13. For this, the pump 14 which is for example a vane pump, is connected by a pressure line 16 to the user 13.

  Due to the application or the system, pressure losses occur in the user 13 and these must be compensated by the device 10. For this, the pressure line 16 includes a pressure switch 18 and a valve In the diagram, the check valve 20 is preferably made in the form of a single assembly with the pressure switch 18, and the common housing 22 is divided by a diaphragm 24 or a piston 48.

  The check valve 20 prevents that when the pump 14 is shut off, the pressure of the user 13 does not escape through the pump 14. The pressure switch 18 ensures that if the pressure in the pressure line 16 or in the As user 13 drops below a set value, pump 14 is automatically connected to compensate for pressure loss. The pressure switch 18 comprises a first electrical contact element 28 preferably rigidly connected to the housing 22. In addition, the pressure switch 18 comprises a movable electrical contact element 30, which in the exemplary embodiment is an element With the click mechanism 32 of the movable contact element 30, the latter moves according to a jump function as soon as, under the effect of the pressure variation, an element of pressure is released. actuation 34 is displaced with respect to the movable contact element 30.

  In the operating state shown in FIG. 1, the movable contact element 30 is applied against the contact element 28 so as to thereby form an electrical contact 31 which closes the electrical circuit 38 supplying the pump 14. pump 14 is thus connected and increases the pressure for the user 13. This pressure is also applied to the membrane 24 which lifts the actuating member 34 by pressing against the movable contact element 30. When reached the upper pressure threshold, the movable contact element 30 moves suddenly so as to leave a gap defined between the fixed electrical contact member 28 and the movable contact element 30; the contact 31 is thus open and the pump 14 cut. When the pressure decreases in the system 13, 16, a return element 40 drives the actuating member 34. After a certain adjustment stroke 46 executed by the actuating member 34, the contact element 30, mo - Bile realized in the form of a spring element 32, switches again by a jump and closes the contact 31 and reconnecting the pump 14. The switching mechanism 32 of the movable contact element 30 can be achieved in different ways .

  It is important that the contact element 30 closes or abruptly opens the contact 31 as the pressure increases or decreases continuously. The movable contact element 30 thus abruptly switches between two click positions 42, 43 which constitute the distance in the space 44 along the adjustment path 46. This distance 44 prevents small variations in pressure from causing For example, the pump 14 is constantly switched on and off by the contact 31. The distance 44 is regulated by the construction of the spring element 32 so that the switch 18 has a hysteresis which has a connection of the pump 14 when the lower pressure threshold is reached and cuts off the supply of the pump 14 when the upper pressure threshold is reached, without requiring for this purpose an additional control or regulation electronics. The contact member 28 and the movable contact element 30 are designed so that the motor current 49 can pass directly through the contact 31, which makes it possible to connect and disconnect the pump 14 without the need for other relays or switching protections. .

  FIG. 2 shows an alternative embodiment of the device 10 according to the invention which performs the movement by jumping of the movable contact element 30 not by a snap mechanism 32, but by the movement by the jump of a body of actuation 34 along the actuating path or stroke 46. For this, the actuating member 34 equipping for example the actuating piston 48 has two latching points 51, 50 which correspond to the two click positions 42 43. The snap points 51, 50 are for example in the form of notches 52 into which the elastic snap-fastening elements 54 penetrate. A spring force 56 can be variably adjusted to the resilient snap-fastener 54 so that when a certain pressure threshold is exceeded or lowered, the actuating member 34 detaches from the actuating point 31 and jumps into the position of the second locking point 50. This movement by jumping of the actuating member 34 is transmitted to the movable electrical contact element 30, which for this reason also switches by a sudden jump and is pressed against the other electrical contact member 28. The distance 44 of the two ratchet points 50, 51 is adjusted to avoid the bouncing of the contact 31 and a level of disturbing level for the pump 14 during slight pressure variations.

  In the state of the device 10 shown in Figure 2, the contact 31 is open. If the pressure falls below a certain pressure threshold, the actuating piston 48 is depressed by the return spring 40. The actuating piston 48 and the actuating member 34, however, descend only when the latching forces 56 of the resilient latching elements 54 are exceeded. Then, the actuating member 34 passes by a jump to the second latching point 50 and the movable contact element 30 passes by a jump in the corresponding click position 42. The contact 31 is thus closed and the pump 14 connected until under the effect of the increase in pressure, the actuating member 34 rises again suddenly and opens the contact 31. It can be adjusted. variable manner the hysteresis (that is to say the difference between the branching threshold and the cut-off threshold) by adjusting the spring force 56 exerted by the resilient snap-fastening element 54.

  Note that the embodiments shown in the figures allow multiple combinations of different characteristics. Thus, for example, the practical realization of the snap mechanism 32 or the latching points 50, 51 and the detent elements 54 may be arbitrary. The important thing is that the movable contact element 30 executes a jump movement on opening or closing the contact 31 for a certain distance 44 between the two click positions 42, 43. directly the electric circuit 36 supplying the motor 49 of the pump 14 without this embodiment being limiting. The choice of the distance 44 between the two click positions 42, 43 eliminates the need for an additional compensation volume so that the pressure switch 18 and the check valve 20 can be integrated directly into the pressure line 16. However, the dis-positive 10 according to the invention is not limited to this embodiment. Preferably, the method according to the invention is applied to the supply of air cushion and pneumatic applications in the field of motor vehicles.

Claims (10)

  1) Device (10) for putting fluid under pressure, comprising a pump (14) connected to a check valve (20) and a pressure switch (18), the pressure switch (18) having at least one element electrical contact device (30), movable as well as means (32, 34) for opening and closing an electrical contact (31), characterized in that the movable electrical contact element (30) moves for a pressure variable according to a jump function along a displacement stroke (46) to open or close the electrical contact (31).   2) Device (10) according to claim 1, characterized in that the electrical contact element (30) is movable between two click positions (42, 43) and in the first click position (42, 43) it closes an electrical circuit (36) and in the second click position (42, 43) opens the electrical circuit (36).   3) Device (10) according to any one of claims 1 or 2, characterized in that the two click positions (42, 43) have a predefined distance (44) along the displacement path (46) to compensate the dynamic pressure variations in the pressure switch.   4) Device (10) according to claim 2, characterized in that the means (32, 34) have a hysteresis which combines two different practical pressure thresholds at the spatial distance (44) of the two click positions (42, 43). ).   5) Device (10) according to claim 1, characterized in that the means (32, 34) are formed as a spring-loaded electrical contact element (32) having a snap-over mechanism (32).   6) Device (10) according to claim 2, characterized in that the means (32, 34) are in the form of an actuating member (34) of an actuating piston (48), the actuating member (34) having two detent points (50) associated with the two click positions (42, 43).   7) Device (10) according to claim 2, characterized in that at the latching point (50), the latching torques of the actuating member (34) are adjustable in a variable way by the forces of spring (56) for presetting the pressure thresholds of the click positions (42, 43).   8) Device (10) according to claim 1, characterized in that the electrical contact (31) directly switches the motor current of the pump (14) and the device (10) comprises in particular no electronic switching circuit.   9) Device (10) according to claim 1, characterized in that the non-return valve (20) and the pressure switch (18) are formed as a common assembly (22) directly connected to the pump (14). ) in particular without additional compensation volume.   10) A method of controlling a device (10) for putting a fluid under pressure using an electric pump (14) in particular according to any one of claims 1 to 9, characterized in that io an element movable electrical contact (30) of a pressure switch (18) closes an electrical contact (31) of the motor supply current circuit (36) of the pump (14) when the pressure threshold is exceeded. bottom, and the electrical contact (31) opens when exceeding a second pressure threshold different from the first.