BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross section through a self-pumping hydropneumatic spring strut unit;
FIG. 2 shows a cross section of a piston rod and a pump rod in isolation with a corresponding number of valves;
FIGS. 3-5 show valves in isolation;
FIGS. 6-10 show various ways in which a positive connection can be produced to hold the valve body according to FIGS. 3-6 in place; and
FIGS. 11-13 show cross sections of an additional variant of a check valve, where the valve body is held in place by a retaining element.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
The spring strut unit for motor vehicles shown in FIG. 1 includes the working cylinder 13, in which a piston 14, mounted on the end of a piston rod 15, slides back and forth. The working cylinder 13 is sealed off appropriately at both ends and is fastened to the axle of a vehicle by appropriate means (not shown). The piston rod 15 is fastened to the vehicle body. The damping forces are generated by the damping valves 16 as the vehicle is being driven.
The spring strut unit according to FIG. 1 has an oil pump, which includes a pump rod 17 and the pump cylinder 18, formed by the hollow piston rod 15. The movements of the vehicle axle caused by irregularities in the road actuate this oil pump, which continually conveys oil, controlled by the first check valve 9a and the second check valve or suction valve 9b, out of the low-pressure chamber 19 and into pump cylinder 18, then via the third check valve or outlet valve 9c into the working cylinder 13 and thus to the high-pressure chamber 20. As a result, the piston 14 and the piston rod 15 are pushed outward until the dynamic level control goes into action by way of a bypass. When the load on the system is removed, the deregulating opening 21 of the pump rod 17 is released, and the vehicle is deregulated again.
The function of the first check valve or drain valve 9a is essentially to open wide in the suction direction and to provide a throttling effect in the drain-out direction, so that the vehicle body will deregulate gently. The advantage of this valve is that, during the suction stroke, the drain notch 22 is opened by the rising valve body 6 and can thus be flushed free of dirt particles. This helps to prevent the danger of clogging at this narrow throttle point. Due to its size, the drain opening 16 does not act as a throttle, and is therefore not subject to the risk of clogging.
FIG. 2 shows a partial area of a piston rod 15, a pump rod 17, and the valves 9a, 9b, and 9c in isolation. In the pump rod 17, furthermore, the deregulating opening 21 is provided, which has already been described in conjunction with FIG. 1.
The valves 9a-9c are simple springless ball check valves, which consist merely of the housing 1 and the valve body 6, in this case in the form of a ball. Because of the simple, uniform cylindrical external contour of the housing 1, modules of this type can be easily installed easily into a recess in either of two axial orientations.
The valves of FIGS. 3-5 are of the same design; they can be provided with a drain notch 22, which is located in the sealing area of the valve body 6. The notch can also be produced afterwards, when the valve seat 3 is finished to exact size. To prevent confusion between parts, the valve housings 1 in question can carry visual identification codes. The housing 1 can be installed in the component in question by pressing it in, by pushing it in, or by peening it tightly in place, or by tightly pressing it in and then also peening it.
FIGS. 3 and 3
a show a housing 1, made preferably of sintered iron, with a bore 2, through which the fluid medium arrives, and a following valve seat 3. The interior of the housing 1 is provided with three guide webs 4, the upper area 5 of which can have different contours. The valve body 6 in the form of a ball can be easily introduced into the housing 1, since appropriate guide play is provided between it and the guide webs 4.
FIGS. 4 and 4
a show the valve body 6 again as a ball, the valve body 6 now resting by the force of gravity on the valve seat 3 of the housing 1. The linear contact between the valve body 6 and the housing 1 is situated below but still near the equator of the ball of the valve body 6. Peening the upper area of the guide webs 5 to form peened areas 7 ensures that the valve body remains captive. The diagram of FIG. 4 shows the valve in the closed position.
FIG. 5 shows a valve in the position which allows the fluid medium to pass through. The valve body 6 in the form of a ball first travels a certain distance in the opening direction and then comes to rest against the peened areas 7; here the valve body 6 makes contact with the housing 1 above but nevertheless near the equator of the ball.
The uniform cylindrical external surface 8 of the housing 1 makes it possible to install valves of this type from both directions. To optimize the sealing action of the valve, the valve seat 3 can be finished to exact size and thus smoothed. During this same work step, the dimensions of the cylindrical external surface 8 of the housing 1 can also be precisely adjusted.
FIGS. 6-10 show the most important ways in which the peened areas 7 in the upper areas 5 of the guide webs 4 can be produced.
FIG. 6 shows the upper area 5 as a thin, elevated, segment-shaped guide web 4, which, as FIG. 6a shows, is provided with a peened area 7 and thus deformed so that it extends radially inward at an angle toward the center.
FIG. 7 shows that the web 7 has a shoulder 10, which allows the bending to occur precisely at this point.
FIGS. 8 and 8
a shows that the guide webs 4 are bent in the area where the greatest amount of material is present. In the case of sintered metal, a bend located in the area of greatest material accumulation prevents the material from fracturing, in that sintered material is relatively brittle.
FIGS. 9 and 10 show two different ways in which a peened area 7 can be produced. A blunt stamping end (FIG. 9) or a pointed stamping end (FIG. 10) of an appropriate tool is used here to drive the material of the housing 1 appropriately inward.
FIGS. 11-13 show another variant of a valve 9, in which the valve body 6 is held in place in the housing by a retaining element 11, where the retaining element 11 is itself held in place in the housing 1 by a peened area 7. According to FIG. 12, which shows a plan view, the retaining element 11 can be provided with a predetermined number of spring tongues 12, which exert an appropriate elastic pressure on the valve body 6, which, in this embodiment, is again designed as a ball.
Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
Patent Application
20070261931
