JPH0380991B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an oscillating piston pump comprising at least one sealing sleeve, the sealing sleeve comprising a radially extending section held at least in part by a piston portion; It relates to a type having a lip area that is in close contact with the cylinder wall.

In a pump or compressor of general construction, there are two plunger pistons and a connecting rod that engages with the plunger pistons.
It is formed by two different parts, which are connected to each other via a piston pin. A disadvantage of this arrangement is that the piston pin and its required grease lubrication are located in hot areas of the pump. This creates problems, inter alia, regarding the service life of the grease for the lubrication of the piston pin. Furthermore, in the aforementioned plunger pistons, lateral guiding forces occur between the plunger piston and the cylinder wall, which generally requires a suitable guide ring for the piston. This guide ring forms the friction part.

In order to avoid the aforementioned drawbacks, pumps with rocking pistons have already been produced. In this pump, the piston and the associated connecting rod are formed in one piece. The piston therefore moves together with the connecting rod. In this arrangement, the pivoting movement of the piston creates a gas-tightness in the central part of the edge of the piston, ie where the rocking piston is inclined with respect to the longitudinal axis of the cylinder. Known oscillating pistons of this type (e.g. US Pat. No. 3,961,869)
In this case, this non-airtightness is compensated for by providing a sealing sleeve.

However, known oscillating piston pumps of this type still have significant drawbacks. The sealing sleeve is stamped from an elastic or elastically deformable plate (often a Teflon plate). This sealing sleeve therefore has a uniform wall thickness in the lip area that lies against the cylinder wall and in the radially extending part which is partially held by the piston part. This sealing sleeve therefore does not have sufficient resistance to the lateral support of the rocking piston. Since the gas forces act in the direction of the crank arm, theoretically no lateral guiding forces can be generated by the gas forces on this rocking piston. However, even in this swing piston, in practice, some lateral guiding force occurs. These lateral guiding forces are due in particular to friction and inertia forces. Lack of lateral support induces premature wear of the lip area. Due to the wear-thinned lip area, the "lower" piston part located "below" the sealing sleeve comes into contact with the cylinder wall and there is a risk of damage. Here, below means close to the crank casing.

The object of the invention is to provide a rocking piston in which the aforementioned disadvantages of known pumps are avoided as much as possible with simple means and at low cost, and at the same time it is possible to obtain a strong lateral guidance for the rocking piston. Our goal is to provide pumps.

The object of the invention is to provide an oscillating pump with at least one single-piece integral sealing sleeve, in which the bottom sleeve part of the sealing sleeve, which serves as a guide for the oscillating piston, is located in the upper part of the oscillating pump. In the case where the piston part is clamped between the piston part and a bearing connected to the piston shaft, the axial wall thickness of the sleeve part is compared to the wall thickness of the lateral lip area of the sealing sleeve. The diameter of the large bearing part, which engages the sleeve part from below, is slightly smaller than the diameter of the upper piston part.

Such an arrangement of the oscillating piston pump or of the sealing sleeve of the oscillating piston pump provides a sufficiently strong support for the tilted oscillating piston and also provides a self-sealing lip seal element. The desired good contact of the lip area of the form is maintained. However, it is not possible to consistently increase the wall thickness of the sealing sleeve, for example to increase the wall thickness of the radially extending sealing sleeve section. If the wall thickness of the entire sealing sleeve is simply increased, the wall thickness of the lip area will also increase correspondingly, and if the wall thickness is too large, the adhesion to the cylinder wall will be impaired.

In an advantageous embodiment of the invention, the maximum wall thickness of the lip area of the sealing sleeve is approximately 0.6 mm. With this arrangement, the lip region adapts continuously to the cylinder wall over its course throughout the working process, thereby avoiding non-sealing properties.
Avoidance of non-sealing properties is extremely important in pump pistons so that the pump function can be effectively maintained without compromising self-sealing properties.

In one advantageous embodiment of the invention, the inner diameter of the pump cylinder is slightly narrower in its central region. In this range, the oscillating piston is in its most inclined position and therefore, for a pump cylinder with a uniform internal diameter, the distance of the sealing sleeve closing between the piston pump and the cylinder wall is at a maximum, but By the measures already mentioned, this spacing is reduced somewhat. Furthermore, in oscillating piston pumps of the type mentioned at the outset, considerable noise is produced. Experiments have shown that the source of the noise is that during the suction stroke, air flows from the crank chamber through the lip area of the sealing sleeve and into the pump chamber. As a result of the air rubbing against the lip area, parts of the lip area separate slightly from the cylinder wall and then come into contact with the cylinder wall again, which causes the noises mentioned above. Another object of the invention is therefore to obtain the quietest possible operation of the oscillating piston pump. According to an embodiment of the invention which solves this problem, in the oscillating piston pump of the type mentioned at the outset, the sealing sleeve is slightly cranked below its radial sleeve section, i.e. in the section with the second lip range. This is due to the fact that it extends towards the room. This significantly avoids air flow from the crank chamber to the pump chamber. As a result, such a rocking piston operates with less noise.

In a particularly advantageous embodiment of the invention, the rocking piston is provided with a second sealing sleeve, which in its lip region is directed toward the crank chamber. In this way, a very simple construction of the oscillating piston pump is obtained.

Next, the present invention will be specifically explained with reference to the illustrated embodiments.

The oscillating piston pump designated by 1 has a pump cylinder 2 in which a oscillating piston 3 is guided. The swinging piston 3 is connected at its end opposite to the pump chamber 4 via a bearing 5 to an eccentric support 6 of the crankshaft. The piston part 7 of the rocking piston 3 has a support 8 and an upper removable piston part 9. A sealing sleeve 10 is fixed between the support part 8 and the piston part 9. According to the invention, in relation to the longitudinal axis of the upper piston part 9, a radially extending sleeve part 11 is provided with a sealing sleeve 1.
It has a larger wall thickness a than the wall thickness b of the rip range 12 of zero. This ensures that even if the annular lip area 12 is sufficiently thin, the pump cylinder wall 1
3 and, as can be seen in FIGS. 1 and 2, a strongly shaped lateral guide for the rocking piston 3 is obtained. The maximum wall thickness b of the lip area 12 of the sealing sleeve 10 is approximately 0.6
mm. If the sealing sleeve is made, for example, from a flexible but not particularly elastic material, such as polytetrafluoroethylene, the wall thickness of the lip area 12 may have a wall thickness b of 0.6 mm or less. Also, sufficient adhesion can be obtained. This allows the sealing sleeve 10 to act like a self-sealing lip seal member.
For this purpose, an annular gap 14 is provided between the upper piston part 9, which has an outer diameter D1, and the inner diameter of the lip region 12. A pressurized delivery medium penetrates into this annular gap 14 and brings the lip region 12 into contact with the cylinder wall at any position of the oscillating piston 3.

The sealing sleeve 10 is integrally formed in the shape of a pot with a thick bottom. In that case, the bottom part forms a radially extending sleeve part 11 (see FIG. 2). Advantageously, the lip area is formed in its undeformed state (FIG. 2) in such a way that it flares laterally outwards, so that even if the delivery medium is under no pressure, it will not press against the cylinder wall 13. Sufficient deformation force is obtained to bring the lip areas 12 into contact. The transition from the radially extending sleeve part 11 to the lip region 12 is designed in the manner of a film hinge so that it can be pivoted slightly. For this purpose, the radially extending sleeve part 11 is preferably
A groove is formed between the rip area 12 and the rip area 12 .

The piston part 9 is removably fastened to the remaining rocking piston part via a screw 16.
As a result, the sealing sleeve 10 can be replaced from the pump chamber 4 side in a known manner. The support portion 8 that supports the seal sleeve 10 from below has a diameter D.
2, which diameter is slightly smaller than the diameter D1 of the upper piston part 9. As a result, when the sealing sleeve 10 is slightly worn and the rocking piston slides, the support part 8 is moved against the cylinder wall 1.
The risk of contacting and damaging 3 is avoided.
The reason why the outer diameter D2 of the support part 8 can be made small in this way is that the radially extending sleeve part 11 has a relatively large wall thickness.
Because the wall thickness a of the radially extending sleeve section 11 is greater than the wall thickness b of the lip region 12, the following advantages are obtained. That is, even if the lip area 12 is partially worn, the oscillating piston 3 can always be sufficiently guided by the radially extending sleeve part 11, so that damage to the cylinder wall 13 is prevented. Avoided. If this sealing function is lost, the pump will no longer be able to discharge, but
A somewhat spontaneous response is obtained that the sealing sleeve 10 should be replaced before mechanical damage to the cylinder wall 13 occurs.

In a particularly advantageous embodiment of the invention, the internal diameter D3 of the pump cylinder 2 is slightly reduced in its central region 17 (see diameter D3' in FIG. 4). The effect of this means is clear when comparing FIGS. 3 and 4. FIG. 3 shows the pump cylinder very schematically. In FIG. 3 the oscillating piston 3 is shown in three different positions. At top dead center and bottom dead center, the longitudinal axis 18 of the rocking piston 3 coincides with the longitudinal axis of the pump cylinder 2 and the diameter D1 of the upper piston part 9 and the diameter D2 of the support 8 are combined with the inner diameter D3 of the pump cylinder 2. If you adapt it appropriately,
The radial gap between the clamping point of the sealing sleeve 10 on the rocking piston 3 and the cylinder wall 13 of the pump cylinder 2 is relatively small. On the other hand, if the oscillating piston occupies a corresponding oblique position in its central position and the pump cylinder 2 has the same internal diameter D3 over its entire axial length, then
This gap will be relatively large. This large gap to be closed by the sealing sleeve 10
SP is reduced by the fact that the pump cylinder 2 has a slightly reduced diameter in its central region 17, as indicated by the diameter D3'. This diameter reduction is adapted to the oblique position of the rocking piston 3. The cross section of the inner diameter of the pump cylinder is circular no matter where it is cut. On the other hand, the change in the gap SP between the rocking piston 3 and the cylinder wall 13 of the pump is
Most pronounced in the pivot plane of the rocking piston. This pivot plane corresponds to the plane of view of FIGS. 3 and 4.
In the longitudinal center plane perpendicular to the drawing plane, the gap between the swing piston 3 and the cylinder wall 13 of the pump does not increase even when the swing piston 3 is tilted. Relatively small inner diameter D
By narrowing to 3", the lip area 12 is compressed slightly radially inwards in the section lying perpendicular to the drawing plane of FIG. 4. Correspondingly, the annular lip area 12 In the region of the pivot plane S of the rocking piston 3, a slightly increased gap between the rocking piston 3 and the cylinder wall 13 can be closed even more easily. is shown in an exaggerated manner for clarity in FIG. 4, and will be explained in more detail later.

The central range 17 means the central range of the piston stroke H. This stroke H is shown significantly enlarged in the drawing. FIG. 5 is a view of FIG. 4 viewed from above.

The displacement of the oscillating piston pump of the present invention is not only comparable to the actual displacement of the known oscillating piston, which is approximately 20/min to approximately 100/min, but also approximately 20/min.
/min~200/min, depending on the case 500/min
It is also possible to have a very large discharge range up to min. In that case, the oscillating piston pump 1 acts in particular as a lubrication-free pump. By non-lubricated pump is meant a pump in which the piston slides along the cylinder wall 13 without lubrication. The advantage of the latter is that the lubricating medium is not mixed with the delivery medium. Liquids and gases are used as discharge media. All the features mentioned above or in the claims may be used individually or in any desired combination. The oblique position of the rocking piston 3, in particular the oblique position shown in FIG. 1, has been exaggerated for clarity. Third
The same applies to the radial spacing of the gaps SP in FIGS.

According to a special embodiment of the invention, when the oscillating piston 3 is in an oblique position corresponding to the crank angle α, the ellipse corresponding to the outer circumference in this oblique position is located at the top dead center or at the bottom dead center. The inner diameter D3α of the pump cylinder 2 changes over the piston stroke H so as to substantially correspond to the inner circumference of the pump cylinder 2 in FIG. This geometrical relationship will now be explained in detail based on FIG.

By configuring the inner diameter D3α over the piston stroke H depending on the crank angle as described above,
We get the following result: That is, the logical outer circumference of the lip area 12 of the sealing sleeve 10 remains, at least approximately, the same size in all stroke positions of the rocking piston 3. The reduction of the pump cylinder 2 is such that when the rip range passes through the central range of the piston stroke H, this rip range is deformed from the shape of the annular ring at top dead center or bottom dead center into various approximately oval shapes. The diameter varies depending on the crank or the corresponding crank angle. In that case, the outer circumference of the rip range does not actually change. In other words, if the inner diameter D3α is appropriately selected over the piston stroke H depending on the crank position, the seal sleeve 10
The lip range 12 has a circular shape with a predetermined outer circumference at top dead center or bottom dead center, and this lip range can be shaped into various oval shapes without changing the length of the outer circumference over the piston stroke H. The outer circumference of this ellipse actually always has the same length as the outer circumference of the circle. The stress on the lip area 12 of the sealing sleeve is therefore relatively low. Therefore, relatively inelastic materials can be used as the material of the sealing sleeve 10, especially in rocking piston pumps, without causing too large a deformation of the sealing sleeve or creating a non-tightness. Large distances are possible without tightening.

The symbols used in FIG. 6 and below are as follows.

l = Crank length r = Crank eccentricity α = Crank angle β at top dead center = Piston inclination angle k at top dead center = Projection of crank length onto the connecting line between piston center point M and crank rotation axis A K=theoretical diameter of the sealing sleeve K corresponds to the diameter D3 of the pump cylinder 2 at top dead center and bottom dead center. In the oblique position of the rocking piston 3, the lip area has an elliptical shape with an outer circumference UE. This outer circumference UE can be determined by the following formula (see Fig. 6).

U _E = π(D+d)/2=π×K (Formula 1) sinα=a/ra a=r×sinα (Formula 2) cosβ=k/l; Furthermore, k ² = l ² −a ² cosβ=√ l ² −a ² /l=√l ² −r ² ×sin ² α/l; (Equation 3
) Furthermore, cosβ=d/D d/D=√l ² −r ²・sin ² α/l; (Equation 4) From Equation 1: D+d=2k D=2k−d; Substituting this into Equation 4, The symbol d in the last equation corresponds to the short axis of the elliptical lip range depending on the crank angle α in FIG. In this way, by making the inner diameter D3α of the pump cylinder 2 dependent on the crank angle α over the piston stroke H, the seal lip can
The theoretical condition that it is possible to work with a practically uniform circumference is fulfilled.

The above geometrical considerations give approximate values.

According to the invention, it is possible in practice to adapt the diameter history D3α to the simple manufacturability of the pump cylinder 2.

In the plan view of FIG. 6, in order to clearly show the sealing area of the tilted piston, the sealing area seen in a perspective view is indicated by a dash-dotted line.

Another embodiment of the invention is shown in FIGS. 7 and 8. The swinging piston pump 101 shown in FIG. 7 is substantially similar to the swinging piston pump shown in FIG. However, in the embodiment shown in FIG. 7, the sealing sleeve 12 has a second lip region below its radial sleeve portion 11, which second lip region extends in the direction of the crank chamber 19. ing. As can be seen from FIG. 7, the swing piston pump 3 is provided with a second seal sleeve 110 near the first seal sleeve 10 already described in FIG. Its lip area 112 extends in the opposite direction to the first sealing sleeve 10, in other words towards the crank chamber. During the suction stroke of the rocking piston, the rip range 1 from the crank chamber 19
2 and no air actually flows into the pump chamber 4. Unwanted peeling movements of the lip area 12 and the pump noises caused thereby are significantly reduced. Practical evidence shows that the oscillating piston pump 101 configured in this way operates very quietly.

If both sealing sleeves 10, 110 are made of the same size, relatively simple manufacture and replacement is possible. It is also possible to use two sealing sleeves 10, 114 in which the thickness a of the radial sleeve portions 11, 111 corresponds to the thickness b of the lip regions 12, 112. By using two sealing sleeves 10, 110, as detailed in FIGS. 1-6,
Radial support can be strengthened. If necessary, the sealing sleeve with the two lip regions 12, 112 can also be formed in one piece. Optionally, the second lip region can be designed as a short, lip-like annular ridge extending into the crank chamber. Such an annular ridge fits well into the cylinder wall 13. In some cases, as shown in FIG.
12 and the cylinder wall 13 an approximately closed annular cavity 20 can be formed. In this way, a kind of labyrinth seal is formed during operation of the oscillating piston pump. For example, along the lip range 112 facing the crank chamber 19,
If some air passes through, this air flow forms a small vortex 21. This situation is shown in an exaggerated manner in FIG. In this case, a certain degree of labyrinth seal is formed in the approximately closed annular chamber, as already mentioned.

A swinging piston pump with two lip areas 12, 112 makes it possible to obtain a relatively large degree of vacuum. With this type of single-stage pump configuration, pressures of less than 100 Torr can be obtained.

A particularly advantageous use of the oscillating piston pump 101 shown in FIG. 7 or 8 is that it is used as a vacuum pump.

FIG. 9 shows a one-piece sealing sleeve that is considerably smaller than in FIG. The lip area 112a facing towards the crank chamber 19 is designed as a shortened annular bulge 22. At the transition from the annular ridge 22 to the radial sleeve part 111, a radially oriented groove 23 is provided, which serves to bring the annular ridge 22 into contact with the cylinder wall 23. It will be done.

The invention is not limited to the illustrated embodiment.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a rocking piston pump according to an embodiment of the present invention, FIG. 2 is a partially enlarged cross-sectional view of a seal sleeve of the rocking piston pump shown in FIG. Figure 4 is an explanatory diagram showing the three positions of the pump cylinder. Figure 4 is an explanatory diagram showing that the diameter of the center of the pump cylinder is slightly reduced. Figure 5 is a top view of Figure 4. Figure 6 is the geometry of the swinging piston. 7 is a longitudinal cross-sectional view of a rocking piston pump according to another embodiment of the present invention, and FIG. 8 is a detailed cross-sectional view of two lip ranges of the rocking piston pump. and FIG. 9 are reduced longitudinal cross-sectional views of another embodiment of the sealing sleeve. 1... Rocking piston pump, 2... Pump cylinder, 3... Rocking piston, 4... Pump chamber, 5
...Bearing, 6...Eccentric bearing, 7...Piston part, 8...Bearing part, 9...Piston part, 10...
... Seal sleeve, 11 ... Sleeve part, 12
...Rip range, 13...Cylinder wall, 14...
Annular gap, 15...groove, 16...screw, 17
... Central range, 18 ... Vertical axis, 19 ... Crank chamber, 20 ... Hollow chamber, 21 ... Vortex, 22 ... Annular ridge, 23 ... Groove.

Claims (1)

Claims: 1. A rocking pump with at least one single-piece sealing sleeve 10, in which the sleeve part 11 forming the bottom of the sealing sleeve, which serves as a guide for the rocking piston 3, In the type clamped between the piston part 9 and the bearing 8 connected to the piston shaft, the axial wall thickness d of the sleeve part 11 corresponds to the lateral lip area 12 of the sealing sleeve 10. A rocking piston pump characterized in that the diameter of the bearing part 8 which is larger than the wall thickness b and which engages the sleeve part 11 from below is slightly smaller than the diameter of the upper piston part 9. 2 Lateral lip range 12 of sealing sleeve 10
The rocking piston pump according to claim 1, wherein the oscillating piston pump expands laterally. 3 Lateral lip range 12 of sealing sleeve 10
3. A rocking piston pump according to claim 1, wherein the maximum wall thickness b of the rocking piston pump is approximately 0.6 mm. 4. The transition from the radially extending sleeve section 11 to the lateral lip region 12 of the sealing sleeve 10 is designed to be slightly pivotable. Oscillating piston pump as described. 5. The oscillating piston pump according to claim 4, wherein a groove 15 is provided in the transition area between the lateral lip area 12 and the sleeve part 11. 6. A sealing sleeve 110 has a second lateral lip portion 1 below the radial sleeve portion 111.
12 or extending substantially towards the crank chamber 19.
The rocking piston pump described in any one of the preceding paragraphs. 7 Two seal sleeves 1 on the swinging piston 3
0,110, the lateral lip area of one seal sleeve faces the pump chamber, and the lip area of the other seal sleeve faces the crank chamber. The rocking piston pump according to any one of items 1 to 6. 8. Both sealing sleeves 10, 110 have the same dimensions and, if appropriate, the wall thickness d of the radial sleeve part 11, 111 corresponds to the wall thickness b of the respective lateral lip area 12, 112. A rocking piston pump according to claim 7, which is formed as follows. 9. Oscillating piston pump according to claim 7, wherein the sealing sleeve with the two lateral lip areas 12, 112 is formed in one piece. 10 both lateral lip areas 12, 112;
Claims 7 to 9, in which a hollow chamber 20 resembling a substantially closed ring-shaped labyrinth seal is provided between the cylinder wall 13 and the cylinder wall 13 loaded thereby. Oscillating piston pump as described.