SOLENOID VALVE WITH HAMMER EFFECT FOR SUDDEN OPENING AND CLOSING ACTIONS

Abstract: Rapid solenoid valve with an armature (15) which, in the deactivated state of the solenoid (11), is spaced from an abutment surface (13) on a valve lifter (8, 9). When the solenoid is activated, the armature strikes the valve lifter and the impact opens the valve rapidly for a very short period.

Description: SOLENOID-VALVE WITH HAMMER-EFFECT FOR SUDDEN OPENING- AND CLOSING ACTIONS. The present invention relates to a solenoid valve comprising a solenoid, a movable armature, a valve closure member ar¬ ranged to cooperate with a valve seat and lifter means acting between the armature and the valve closure member, arranged to transmit the movement of the armature in the valve opening direction to the valve closure member. In solenoid valves of this type, the closure member is usual¬ ly joined to the armature in such a way that its movement follows the movement of the armature. Already at the initial movement of the armature in the opening direction, the valve closure member begins to move from its valve seat. In order to achieve a rapid opening and closing cycle, such valves require relatively complicated drive circuits. One example of such a valve with a drive circuit specially designed for a rapid operating cycle is shown in US-A-4 620 259. The purpose of the present invention is in general to achieve a solenoid valve of the type described by way of introduc- tion, which, without the need for complicated drive circuits, can be made to open very rapidly and keep the valve open during a very short time. In particular, the purpose is to achieve a valve which is particularly suited for use in connection with soot sampling measurements when testing internal combustion engines, where one needs to collect a very limited amount of gas during a very short time. This is achieved according to the invention by virtue of the fact that the armature and the lifter means have abutment surfaces which, in a deactivated state of the solenoid, are spaced from each other, and are so arranged that the abutment surface of the armature, when the solenoid is activated, strikes the abutment surface of the lifter means after a certain movement of the armature. The invention is based on the idea of using the "hammer effect" which can be achieved by providing a gap between the armature and the valve lifter means. Preferably the gap between the abutment surfaces of the armature and the lifter means is so great that the abutment surface of the armature strikes the abutment surface of the lifter means just before the armature has reached its end position, so that it has a maximum kinetic energy. The kinetic energy of the armature is thus transmitted as an impuls to the lifter means. The shock wave is propagated through the lifter means to the valve closure member which is lifted from its seat. The invention provides a simple and inexpensive valve which can be designed so that the period from when the armature strikes the lifter means until the valve opens is not more than a fraction of a millisecond. The invention will be described in more detail with reference to examples shown in the accompanying drawings, where Fig l shows a schematic perspective view of one embodiment of a valve, and Fig. 2 shows a perspective view of certain details of the valve in Fig. 1 on a larger scale. The valve comprises a cylindrical metal body 1 with a central bore 2 which leads to a valve tube 3, e.g. of stainless steel, which is fixed in the body 1. The tube 3 extends through a second cylindrical metal body 4 and has its lower end in the form of a valve seat 5 for a valve disc 6, which is supported by a valve rod 7, made of Inconel for example, extending through the valve tube 3 and bore 2. The rod 7 is threaded at its upper end and a valve lifter in the form of two internally threaded cylindrical elements 8,9 is screwed onto the rod 7 and is surrounded by a cylindrical guide 10 at the upper end of the bore 2. The solenoid 11 is fixed at the upper end of three cylindrical guide rods 12 (two shown) , which extend through bores 12a in the body 1 and are fixed at their lower ends to the lower body 4. The tube 3 is displace- able relative to the body 4 and, with the aid of adjustment and lock means (not shown) , the body l is displaceable and lockable in various vertical positions on the guide rods 12. In this manner, the distance between the upper surface 13 of the upper valve lifter element 8 and the downwardly directed opposite surface 14 of the solenoid 11 anchor 15 can be adjusted. A radio channel 16 in the body 1 communicates with the bore 2 and forms together with the bore and the tube 3 a gas pas¬ sage. The bore 2 has an upper portion 21 of greater diameter than its lower portion 22. A first shoulder 23 formed between the portions serves as a support for a washer 24 and an O- ring 25, which serves to seal between the valve rod 7 and the wall of the bore 2. The O-ring 25 can be made of viton, which can withstand the hot gases encountered when using the valve for sampling combustion gases. A second shoulder 26 forms a support for a return spring package 27 consisting of a pair of spring washers 28, a helical spring 29 and an intermediate washer 30. A spring package of this design has a non-linear return characteristic curve. In practical tests with a valve device according to the invention, the solenoid was activated with a voltage of 170V. The gap between the surface 13 of the valve lifter element and the surface 14 of the armature in the deactivated state of the solenoid was adjusted so that the surface 14 of the armature struck the surface 13 of the element immediately prior to the lower end position of the armature. The masses of the active components, i.e. of the armature 15 and the valve rod 7 with its valve disc 6 and the lifter elements 8,9, were adapted to each other and to the spring package 27 so that the valve opened and closed in circa 0.7 milli¬ seconds with a maximum stroke length of the rod of circa 0.5 millimeters. The valve according to the invention can be mounted on the cylinder head of an internal combustion engine and be used for sampling of combustion gases. The radial bore 16 is coupled to an analyzer unit. It can of course also be used in other contexts where there is a rapidly varying cycle. It is especially suitable for use in periodically recurring measur¬ ements with a very small "duty cycle", since the major por¬ tion of the total cycle is used for acceleration of the armature and only a very small portion for the impact against the lifter elements. The valve rod must in certain cases be able to withstand both high mechanical stresses and high temperatures. The material in the rod is selected with regard to this and to the respon¬ se time, the sampling environment etc. Conceivable materials are, in addition to steel alloys, Inconel and titanium. Within the scope of the invention, it is possible to mount a separate movable mass between the armature 13 and the lifter elements 8,9. The armature then strikes this intermediate mass, which in turn strikes the lifter elements. In this manner, an even more rapid valve can be achieved. The weight of the intermediate mass is optimized in relation to the weight of the other movable portions of the valve so that the momentum is transferred from the armature to the valve lifter elements with the least possible loss of energy. In theory, the weight of the intermediate mass should be equal to the sum of the weight of the other ovable portions of the valve. In practice, however, this weight must be adjusted taking into account various losses in the device. The arrangement with an intermediate mass with optimized weight provides advantages in the form of reduced wear, reduced recoil (the intermediate mass should preferably come to a stop after having struck the valve lifter) and reduced risk of deformation.

Claims: CLAIMS 1. A solenoid valve comprising a solenoid, a movable arma¬ ture, a valve closure member arranged to cooperate with a valve seat, and lifter means acting between the armature and the valve closure member, arranged to transmit the movement of the armature in the valve opening direction to the valve closure member, c h a r a c t e r i z e d in that the armature (15) and lifter means (7,8,9) have abutment surfaces (14,15), which in the deactivated state of the solenoid (11) are spaced from each other, and are so arranged that the abutment surface (14) of the armature, when the solenoid is activated, strikes the abutment surface (15) of the lifter means after a certain movement of the armature. 2. Solenoid valve according to Claim 1, characterized in that the armature (15) is movable between two end positions and is so arranged relative to the abutment surface (13) of the lifter means (7,8,9) that the abutment surface of the armature strikes the abutment surface of the lifter means when the armature, after activation of the solenoid (il) , has moved a major portion of the distance between its end posi¬ tions. 3. Solenoid valve according to Claim 1 or 2, characterized in that spring means (27) are arranged, which when the sole- noid (11) is deactivated, hold the valve closure means (6) against its seat (5) . 4. Solenoid valve according to any one of Claims l - 3, characterized in that the valve closure means is a valve disc (6) mounted on a valve spindle (7) , and that the spindle is joined to a mass (8,9), which is displaceably mounted in a guide (10) and has said abutment surface (13) . 5. Solenoid valve according to any one of Claims 1 - 3, characterized in that the valve closure member is a valve disc (6) arranged on a valve spindle (7) and that the lifter means comprise a mass which is movable relative to the arma- ture (15) and the spindle (7) , which has said abutment sur¬ face and an additional abutment surface disposed after a certain movement of the mass to strike an abutment surface (13) on an element (8) solidly joined to the spindle.

Inventors: HOEGLUND ANDERS, LUNDGREN STAFFAN, ROSENQUIST MATS, HOEGLUND, ANDERS, LUNDGREN, STAFFAN, ROSENQUIST, MATS
Applicants: VOLVO AB, AB VOLVO
Application year: 1991
Main classification: F16K31
IPC codes: F16K31