APPARATUS FOR OPERATING PNEUMATICALLY SPRUNG CHAIR SEATS AND THE LIKE

Abstract: An apparatus which is intended for operating pneumatically sprung seats and the like includes a pressure regulator and a venting valve. The pressure regulator and venting valve are built together into one unit, the housing (2) of the pressure regulator consisting of a piston in the venting valve, which is formed as a slide valve (1, 2) and the pressure regulator and venting valve are served by a common operating means (26).

Description: APPARATUS FOR OPERATING ^ ^EUM TI CALL £_ j^RUN JG_ CHAIg Technical Fi .el ά The invention relates to an apparatus intended for operating pneumatically sprung chair seats and the like and includes a pressure regulator and a vent valve. Background Art For operating pneumatically sprung seats, e.g. the driver's seat in a vehicle which is provided with a bellows or piston as springing means, an adjustable pressure regulator is usually used for setting the air pressure. The pressure is regulated by the driver when he sits on the seat, so that suitable sitting height is obtained. By increasing the pressure the seat is raised, and by lowering the pressure the seat is lowered. For getting in and out of the vehicle the seat shall normally be in its lowest position, i.e. there will be no excess pressure in the bellows (piston) . To avoid resetting the pressure regulator each time a person gets in or out of the vehicle, a separate three-way valve is used, by which the bellows (piston) in the seat can be connected to the regulator or vented to atmosphere as required. The regulator and this vent valve are then usually placed on different sides of the seat, since there is restricted space for operating means. The arrangement results in that many hose connections between the components need to be made under the seat. Disclosure of Invention The present invention has the object of combining the pressure regulatinα and venting functions in an apparatus constituting a single unit, and which is sufficiently compact for being built into the frame of the chair seat, which results in a minimur, of hose connections and which has a common operating means for both unctions. The desired result is obtained by giving the apparatus the characterizing features disclosed in the following claim 1. Description of Figures A pair of embodiments of the invention will now be described here with reference to the accompanying figures. Figure 1 is a longitudinal section of a first embodiment of the apparatus. Figure 2 is an end view of the apparatus seen from the left hand end in Figure 1. Parts of a handwheel are excluded. Figure 3 is a partial view along the line III-III in Figure 1. Figure 4 is a section to an enlarged scale of a central portion of Figure 1. Figure 5 is a partial longitudinal section to an enlarged scale corresponding to the one in Figure 1 , but with some of the interior parts of the apparatus left unsectioned. Figure 6 is a longitudinal section through a second embodiment of -the apparatus with a regulator housing (a piston) illustrated in an inner end position in a valve housing. Figure 7 is a longitudinal section through the valve housing of Figure 6 with the regulator housing taken to an outer end position in the valve housing. Fiσure 8 is a cross section according to the line VIII-VIII in Figure 6. Preferred Embodiments Immediately following is a description of the embodiment according to Fiσures 1 - 5. valve body 2 is enclosed in a valve housing 1 so that the body is axially movable in the housing. This movement is limited at one end position of the valve body by a shoulder 3 thereon, which engages against an abutment 4 in the housing 1 , as illustrated in Figure 1. The opposite end position of the valve body is determined by a circlip 5 engaging against the outer side of the abutment 4, as illustrated in Figure 5. The valve body 2 is not rotatable in the housing 1 , since the portion of it situated between the shoulder 3 and the groove for the circlip 5 has the cross section of a polygon, e.g. it is hexagonal, with the hole in the valve housing 1 surrounded by the abutment 4 being given a complementary configuration. There is a hose nipple 7 at the end of the valve body, and it is connected by a hose to a compressed air source with a given available pressure, which is then conventionally reduced by a regulator built into the valve body 2 to the desired working pressure, which is supplied to the unillustrated bellows piston in the seat by a hose connected to the outlet nipple 8, this hose not being illustrated either. The function of the regulator will now be described with reference to Figures 1 and 4. Concentric with the central axis of the valve 2 there is a valve rod 9 provided with two valve means 10 and 11, each comprising a dish 10a, 11a an 0 ring 12 and a spacer sleeve 13. The dish 10a rests with its tubular end against a head 9a on the valve rod 9, thus limiting its movement along the rod in one direction. The 0 ring 12 is pressed into the dish 10a, and on its other side facing away from the dish the spacer sleeve 13 is mounted on the rod 9, and fixed to the rod 9 by beinq swaged into a radial groove 9b on the rod. The valve means 10 is thus located on the rod between the head 9a and groove 9b. i The valve means 11 is located in a similar way to the rod 9, but with the difference that the tubular portion 11b of the dish 11a is swaged into a groove 9c on the rod instead of engaging against a head. The mutual distance between the valve means 10 and 11 is thus fixed. The 0 ring of the valve means 10 seals against the seat 14a of a screwed insert 14, which is tightened down in the valve body 2 into a metallic seal against a sealing edge 15. The valve means 10 is kept urged against the seat by a light spring 16. In a corresponding manner the valve means 11 seals against the seat 17a on a piston 17, . which is axially movable in a cylindrical bore 18 in the valve body 2, a sealing ring 19 forming a seal between the piston and cylinder wall. The piston 17 is acted on by a spring 20 which/ when there is no excess pressure in the chamber, urges the piston towards a shoulder 22 on the bore 18. In this position the valve means 10 is kept lifted from the seat 14a, and since the central hole 14b in the insert 14 is greater than the outside diameter of the spacer sleeve 13 there is formed a gap between them which forms a free passage between the nipple 7 and the chamber 21. Compressed air passing in via the nipple 7 then creates a pressure in the chamber 21 which acts on the piston 17 against the bias of the spring 20. When the compreεsive force exceeds the spring bias, and the spring is compressed, the valve means 11 accompanies the movement of the piston 17 to a certain extent, due to the bias of the spring 16. The rod 9 accompanies the valve means 11, the rod bringing with it the valve means 10 until the latter reaches the seat 14a the compressed air supply to the chamber 21 then ceasing. The force from the air pressure on the piston is then equal to the spring bias, and the piston remains in this position. With the valve body 2 in its end position illustrated in Figure 1 the chamber 21 is in communication via bores 24 and groove 25 with the outlet nipple 8, which is connected by a hose to the bellows/piston, which then has the same pressure as there is in the chamber 21. This pressure is regulated with the aid of a handwheel 26, which via a threaded spindle 27 moves a thimble 28 when it is turned, so that the spring 20 is compressed or extended, the spring bias on the piston 17 thus being changed and thereby the air pressure in the chamber 21. The spindle 27 is screwed into a member 29, which is in turn securely screwed into the valve body 2. The valve housing 1 is fastened to the seat frame 30 by a nut 31. A leaf spring 32 is fastened to the member 29 by a nut 33, and a folded edge 32a on the spring engages against a spanner flat 29a on the member 29 such as to prevent the spring from turning in relation to the valve body 2 and thereby in relation to the frame 30. The handwheel 26 is of plastics material and has a bowl shape with a flange 26a and a hub 26b, in which a threaded metal bush 34 has been moulded. With the aid of a lock nut 35 the handwheel can be set axially and locked against turning in relation to the threaded spindle 27, which at the end engaging against the thimble 28 has a flange 27a preventing it from being screwed out of the member 29. There are axial ridges 26c on the inside of the weakly tapering flanqe 26a of the handwheel 26. The leaf spring 32 is bent at an angle and dimensioned such that when it and the handwheel are fitted, its free end 32b thrusts in behind the flange 26a and presses radially outwardly against it such that it will snap over one of the ridges 26c and into the intermediate space 26d between the ridges when the handwheel is turned. The spring 32 thus offers a certain detent action against unintentional turning of the wheel. The handwheel 26 and spring 32 are not in place when the apparatus is to be fitted to a seat. The valve housing 1 is thrust from the inside of the seat frame 30 through a hole therein and fastened with the nut 31. The spring 32 is then placed on the member 29 and locked with the nut 33. The nut 35 and the handwheel 26 are threaded on to the spindle 27 and locked against it. The handwheel is turned anti-clockwise until it is stopped and is pressed against its inmost end position (as illustrated in Figure 1 ) . Compressed air is connected to the nipple 7 and a pressure gauge to the outlet nipple 8, and the handwheel is turned clockwise until the lowest desired operating pressure is shown on the gauge. In this position the handwheel 26 is provided ' with a stop 36 which is placed on one side of the spring 32 so that the spring thus prevents the handwheel from being turned back again (anti-clockwise) . The stop 36 is locked to the handwheel 26 by its hook-shaped end 36a being taken over the edge of the flange 26a and its other end 36b snapped over the circular collar 26e on the outside of the handwheel. The handwheel can now be turned clockwise up to at most one revolution minus the collected width of the spring 32 and stop 36 to set the desired pressure. The handwheel 26 is pulled outwards to its outmost end position (Figure 5) for lowering the seat to its bottom position. The valve body 2 is provided with three 0 rings 38, 39 and 40 in grooves in the circumference of the valve body for sealing against the bottoms of the grooves and the inner wall 41 of the valve housing 1. A portion 42 of the valve body between the 0 rings 38 and 39 is waisted, and between the 0 rings 39 and 40 there are radial bores between the chamber 21 and a groove 43 in the circumference of the valve body. When the valve body 2 is moved from its inward end position (Figure 1 ) to its outward end position (Figure 5), the 0 ring 39 passes over the groove 25 in the valve housing 1. In this position communication between the bellows/piston of the seat and the chamber 21 via the nipple 8 is interrupted, while the nipple 8 is connected via the waisted portion 42 to the vent 37, from which air in the bellows/piston of the seat is dissipated. When the handwheel 26 is pressed in again, the bellows/piston is filled with air at the pre-set pressure. The function of the valve means 11 and seat 17a on the piston 17 is as follows: For sudden heavy movement of the seat, e.g. due to a pothole in the road and the like, the load on the seat varies and thereby the load on the bellows/piston. If the load momentarily decreases below a normal value, the pressure in the bellows/piston falls accordingly, air from the chamber 21 then passing out through the outlet 8 and the pressure on the piston 17 decreases. The spring 20 then urges the piston inwards from the set equilibrium position, the valve means 10 leaving the seating 14a and air flows into the chamber from the inlet 7 until the pressure has been evened out, and the piston once again returns to its position of equilibrium. When the load once again returns to normal and the pressure increases, the excess air cannot pass back again the same way it came, but the increased pressure in the chamber 21 and the piston 17 compress the spring 20, the piston 17 moving after the spring. A gap then occurs between the valve means 11 and the seat 17a, and air from the chamber 21 can pass out through a bore 44 in the piston and into the spring housing, from which it is then evacuated through a hole 45 in the valve body 2 and slips out through a gap 46 between the valve body 2 and housing 1. When the pressure in the chamber 21 accordingly decreases, the piston once again returns to its pre-set normal position and the seal between the valve means 11 and seat 17a is made good again. The invention is naturally not restricted to the embodiment illustrated and described above, and may be varied in several respects within the scope of the inventive concept. One such variation will be summarily described belov; and with reference to Figures 6, 7 and 8, in which the reference numerals for the parts agree with those of Figures 1 - 5 as far as they are identical or have the same function. Figure 6 is a longitudinal section through the apparatus with the regulator housing (piston) 2 in its inner end position in the valve housing 1. Figure 7 is a longitudinal section through the valve housing 1 and piston 2 in its outer position. Figure 8 is a cross section through the handwheel spindle. The placing of the hose nipples 8 (for supplying air to the bellows/piston in the seat) and 37 (for venting the air in the bellows/piston) differs in this embodiment from the one previously described. Placing the nipples in axial ducts 8a and 37d in the valve housing 1 simplifies the plastic pipefitting when the apparatus is built into the seat and enables the air outlet through the piston 17 via the hole 45 to be prevented from leaking out through the gap 46 (Figure 5) , since such leakage cannot be accepted in certain cases, e.g. in the driver's cabin. Since the duct 37d extends right into the chamber 47 which is in communication with the hole 45, and since the member 29 of the regulator housing 2 is provided with an 0 ring 50 sealing against the valve housing 1 , the air from the opening 45 is now directed out through the outlet nipple 37, which is vented outside the driver's cabin. When the regulator is moved to its outer position (Figure 7) the nipple 8 will be in communication with the chamber 48 via the bore 8a and groove 25 in the valve housing 1 , the chamber being in turn vented through the outlet nipple 37 via the bores 37a and 37d. To achieve the communication duct 37a, a hole 37b - 37a must be bored through the duct 37d, the outer end of this bore then being sealed off. e.g. by a ball 37c being pressed in from the outside of the valve housing 1. The embodiment illustrated in Figure 6, 7 and 8 differs from the one already described as regards means for setting regulated pressure and for retaining the handwheel in its set angular position. As in the previous description, the handwheel spindle 27 is provided with a head 27a at its end facing towards the regulator and must be screwed into the member 29 from the inside. There is a circlip 96 in a groove on the spindle and this circlip together with the head 27a limits the axial movement of the spindle 27 in the member 29, this movement being adapted to give the necessary compression of the spring 20 corresponding to the desired pressure regulation range. The spindle actuates a spring cover 28 via a ball 54, to reduce the torque on the piston 17 and prevent it from being turned round with the handwheel due to friction. To set the lower limit of the pressure regulation range, i.e. calibration of the regulator setting, the handwheel 26 is turned to its outmost position when the head 27 of the spindle engages against the bottom of the bore 29b in the member 29, which is then screwed into the regulator housing 2 until the spring gives a force on the piston 17 corresponding to the desired pressure. The member 29 and piston 2 can then be mutually locked in this position using the locking ring 55 or by gluing, if the regulator/valve body 2 is pulled out of the valve housing 1 , which would require removal of the circlip 5 during calibration. Service on the regulator is facilitated by its being easy to remove from the valve housing 1 by releasing the circlip 5, it thus not being necessary to dismantle the valve housing 1 from the seat frame in changing regulators. The detent means against unintentional turning of the handwheel 26 is illustrated in Figure 8. In the member 29 there are longitudinal grooves 29a in the circumference of the bore 29b in which the head 27a of the spindle 27 is situated. The grooves have an even number and are uniformly distributed. A hole 27b is drilled through the head 27a in a plane at right angles to the longitudinal axis of the spindle. The distance between the centre lines of the hole and the spindle should be about a 1/4 of the spacing between two grooves 29a in the member 29. In the hole 27b there are mounted a helical spring 52 with a ball 51 at one end and a ball 52 at the other end. When the spindle 27 is turned, the balls 51 and 52 will alternately mesh with one of the grooves 29a so that when one is in a groove the other engages against a spline 29c constituting the circumference of the bore 29b between two grooves 29a. In this way the number of detent positions for the handwheel 26 will be double that of the number of grooves 29a. By correctly dimensioning the spring 53 it will be achieved that there is a suitable resisting torque for the handwheel 26.

Claims: CLAIMS 1. Apparatus intended for operating pneumatically sprung chair seats and the like and including a pressure regulator and a venting valve, characterized in that the pressure regulator and venting valve are built together into one unit, the housing (2) of the pressure regulator comprising a piston in the venting valve formed as a slide valve (1, 2) and in that the pressure regulator and venting valve are served by a commom operating means (26) . 2. Apparatus as claimed in 1, characterized in that the operating means (26) comprises a handwheel which, on being turned, actuates the pressure regulator and by axial movement controls the venting valve. 3. Apparatus as claimed in 1 or 2, characterized in that the housing (2) of the pressure regulator is axially movable but not rotatable in the venting valve housing (1).

Inventors: ERIKSSON AAKE, ERIKSSON, AAKE
Applicants: PRIMUS SIEVERT AB, PRIMUS-SIEVERT AB
Application year: 1988
Main classification: G05D16
IPC codes: B60N2, G05D16