JPH0650273A - Rotary piston pump - Google Patents

Abstract

PURPOSE: To provide an oscillating piston pump capable of avoiding the slide of a pivot joint mounted on a vane end thereby being suitable to be used as a dry rotor independent of a lubricant circuit of a motor vehicle engine. CONSTITUTION: A cylindrical rigid support ring 7 is rotatably supported on a pin 3.1 and has a width of a pump casing 1. A sole oscillating vane 12 with one end rotatably supported on a generatrix of the pump casing 1 and the other end rotatably supported on a generatrix of the support ring 7 is provided. The oscillating vane 12 has the width of a pump casing 1 and a length longer than or the same as two times of an eccentric distance ε between the pump casing 1 and the support ring 7 but shorter than or the same as two times of the radius of the support ring 7. The pump casing 1 or the pin 3.1 is rotatably driven. A fixed component of the structural members has a pump inlet 16 and a pump outlet 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillating piston pump for generating a negative pressure in a gaseous medium, as defined by the superordinate concept in claim 1.

[0002]

Oscillating piston pumps of the type mentioned are known and are applied in motor vehicles for servo systems, in particular for braking force boosters. For this reason, vane pumps or swirl vane pumps are frequently used.

A swirl vane pump of this kind is known, for example, from German Patent Specification DE 539608. In the swirl vane pump, the pump casing rotates concentrically with the crankshaft. A stationary cylindrical core is eccentrically located on the crankshaft, a control ring slides on the outer peripheral surface of the core, and a plurality of circumferentially distributed slide pieces are provided on the control ring. ing. The control ring is driven by the guide disc at an angular velocity equal to the pump casing. A vane end is pivotally attached to each slide by means of a joint, the vane extending up to the inner wall of the casing and carrying one roller each, which roller extends over the entire width of the casing, and Two
It is crimped onto the casing wall in order to seal the vane compartments which are respectively formed between the two vanes and the casing and the stationary cylinder. In the known swirl vane pump, each outer end of the vane slides along a driven pump casing. At that time, a high peripheral velocity is generated, the component is heated due to the sliding friction, and the wear is unavoidably generated. Therefore, the components must be lubricated at all times.

Also known from US Pat. No. 1,253,460 is a vacuum pump in the form of a swirl vane pump, in which the vanes are fixed to a joint, which on the one hand is a casing. On the inside, and on the other hand, on a sliding piece on the outer circumference of an eccentrically supported cylindrical cylinder. When the pump casing rotates, the sliding piece at the inner end of the vane slides along the slide path on the outer peripheral surface of the stationary cylindrical cylinder eccentrically arranged with respect to the casing rotation axis. At that time, the size of the pump chambers located between the adjacent vanes, the casing wall and the stationary cylindrical cylinder increases or decreases periodically, and a pumping action occurs based on this increase or decrease. In this known swirl vane pump, a stationary cylindrical cylinder is provided with a pump inlet and a pump outlet.

The disadvantages of known swirl vane pumps are:
Due to the large number of pivot joints and the movement of the slides along the slideways, the slideways are subject to wear and of course need to be lubricated.

Furthermore, German Patent DE 6471
Displacement pumps are known from U.S. Pat. Nos. 72 and 678,936, in which the piston of the displacement pump is driven by an eccentric wheel and, when actuated, makes a circular oscillating movement in the pump casing. In this machine the suction chamber is isolated from the pressure chamber by a radial control lead. The control lead piece is fixedly connected to a part of the outer circumference of the piston and is movably mounted in the pump casing. The problem with this machine is that the sealing action of the control lead piece in the pump casing continues when a differential pressure is produced and the sliding surface of the control lead piece wears.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an oscillating piston pump which can be applied as a dry rotor independent of the pivotal joint attached to the end of the vane and thus independent of the lubricating oil circuit of the automobile engine. Is to provide.

[0008]

The constitution means of the present invention for solving the above-mentioned problems is as described in claim 1 of the claims. In the oscillating piston pump according to the invention, a cylindrical pin is eccentrically mounted in the pump casing with a rigid support ring concentrically surrounding the pin and closing itself. The pin and the support ring together form a rocking piston. In this case, the support ring is supported on the outer circumference of the pin and is rotatable relative to the pin. The pump casing and the support ring or wobble piston are connected to each other by only one common vane, the inner end of the vane being on one bus of the support ring and the outer end of the vane being the pump casing. Is pivotally connected on one bus. In that case, the oscillating piston and the vanes connecting the oscillating piston to the pump casing have the width of the pump casing closed by the casing lid. The length of the vane is greater than or equal to twice the eccentric distance between the pump casing and the support ring or piston, but less than twice the radius of said support ring or It is equal to twice.

In such an oscillating piston pump, whether to drive the pump casing or the pin is determined depending on where the driving force is introduced, but in any case, the position is fixed. Has a pump inlet and a pump outlet. During operation, the piston has a precisely guided movement, and the center point of the pin is
Since a circular movement is performed around the casing axis, lubrication is not necessary if a seal gap is provided between the piston and the pump casing. The only movement that will generate friction is the pump casing 1
Swirl motion of the vane and piston along a short circular path segment about the swirl point of the vane end pivotally mounted on the bus, and swivel motion at the joint. However, in order to reduce the friction and wear in this case, it is possible to perform a one-time lubrication with a solid lubricant or to apply a material pair with suitable sliding or emergency rolling properties. . In particular, the piston, casing and bearing cover are made of plastic with good dry rotation properties, while the pump shaft and the eccentric are made of tough steel.

Advantageous embodiments of the oscillating piston pump according to the invention are obtained by means of the components defined in claims 2-18.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In the oscillating piston pump shown in a longitudinal section in FIG. 1 and in a transverse section in FIG. 2, a pot-shaped pump casing 1 is closed axially by a substantially flat casing lid 2. A piston 3 is fitted inside, and the piston is fixed to a pump drive shaft 4 so as not to rotate relative to it. The piston 3 comprises a pin 3.1 and a support ring 7, which will be explained in more detail later. The pump drive shaft 4 is located within the pump casing 1
It is rotatably supported via two rolling bearings 5, 6, in which case the first rolling bearing 5 serves as a fixed bearing at approximately the midpoint in the vertical direction of the pump casing 1, and the second rolling bearing 6 serves as a movable bearing. Is arranged in the casing lid 2. To this end, the bottom of the pump casing 1 is drawn into the pump interior, whereby the hub 21 is arranged to reach the area of the pump casing 1 at the longitudinal midpoint, by means of which it is possible to carry out the fixed rolling. A bearing 6 is received with the pump drive shaft 4 and a coupling sleeve 4.1 of the pump drive shaft 4 is fitted in the hub with radial play. The pin 3.1 of the piston 3 has an eccentric hole, and the pump drive shaft 4 is press-fitted in the eccentric hole. Said support ring 7 is formed by two pot-shaped tube sections 8, 9 which are respectively radially inwardly facing shoulders 8.1, 9.
1 and are fitted in and out of each other. For this purpose, the two tube sections are preferably crimped to each other at both ends and have a mutual gap of approximately 0.5 to 0.8 mm in the axially intermediate section. This is due to the different thermal expansion between the pump drive shaft 4, the pin 3.1, the support ring 7 and the steel ring of the rolling bearings 10, 11 bearing said pin 3.1 to the support ring 7. Is compensated by the mutual gap. In this case, it is advantageous to use different materials for the components, such as steel, aluminum alloys, bearing materials and the like. The decisive factors for this are strength and, in some cases, easier and more accurate manufacturability and wearability. Further, the multi-layer shell structure of the support ring 7 and the rolling bearings 5, 6;
With the arrangement of 1, the outer tube section 8 has a constant outer diameter and cannot be deformed during operation by thermal influences. Radial thermal expansion is absorbed by the inner tube section 9 and the gap provided between the inner and outer tube sections 8, 9.

A pin 3.1, which is connected to the eccentrically arranged pump drive shaft 4 in a non-rotatable manner and which is driven by the pump drive shaft, has two pipe sections 8 forming a support ring 7. 9, which are in particular rollingly supported by piston bearings, the shoulders 8.1, 9.1 of the two pipe sections being fitted between the casing bottom of the pump casing 1 and the casing lid 2 with a narrow sealing gap. It is rare. In this case, the rolling bearings 10, 11 are clamped together by spring packets 22, eg disc springs, so that the rolling bearings rotate both axially and radially without play.
Furthermore, the pin 3.1 has a counterweight 3.2.
And the appropriate notch 20 compensate the mass for the pump drive shaft 4 and do not generate unbalance or harmful inertial force by the pin 3.1 and the rolling bearings 10 and 11 which rotate during the operation of the rocking piston pump. Is configured.

The pump casing 1 and the outer pipe section 8 of the support ring 7 are pivotally connected to each other by means of oscillating vanes 12. For this purpose, a joint pin 13 is fixed to the outer periphery of the support ring 7, and the joint pin 13 is fitted by a joint socket formed at one end of the swing vane 12. The other end of the swing vane 12 is fixed to the rotary joint 14 and is located in the circumferential recess 15 of the pump casing 1. The swing vane 12 has a width substantially equal to the axial length of the piston 3. The oscillating vanes seal the plurality of working chambers formed during operation of the pump in the circumferential and axial directions, so that they flow in through the pump inlet 16.
That is, the working medium to be sucked in, in particular air, is discharged from the working accumulator (not shown) to the pump outlet 17.
Since a substantial part of the movement of the piston 3 in the pump casing 1 takes place along the sealing surface of the swing vanes 12, the swing vanes are made of aluminum bronze, artificial carbon,
It is particularly advantageous to make it from a suitable bearing material with good sliding properties, such as plastic. Furthermore, the oscillating vane 12 is curved in its longitudinal direction and has a radius of curvature corresponding to the radius of the piston on the inner side and to the radius of the pump casing 1 on the outer side. The circumferential recessed portion 15 is configured as follows in the radial direction and the circumferential direction. That is, when the piston 3 comes into contact with the pump casing wall, the swinging vane 12 together with the joint pin 13 is submerged in the wall of the pump casing 1. This reduces the wasted space of the pump and improves the volumetric efficiency.

The length dimension of the oscillating vanes 12 is equal to or larger than twice the eccentric distance ε between the pump casing 1 and the support ring 7, but 2 times the radius of the support ring 7.
It is important to be equal to or less than twice. In this case, the joint pin 13 and the rotary joint 1
4 is defined as the length of the swing vane 12. Furthermore, note that the length of the oscillating vane 12 will be additionally described as a precaution in connection with the length dimension of the oscillating vane 12.
As a result, the length of the circumferential recessed portion 15 is determined based on the circumferential distance between the pump inlet 16 and the pump outlet 17, and
The circumferential distance is important for the maximum suction volume of the pump.

During operation of an oscillating piston pump, in particular as a motor vehicle vacuum pump for actuating a braking force booster or other servo drive, the pump shaft 4 passes through the coupling sleeve 4.1 and the arrow 18 It is driven at a high rotation speed in the rotation direction indicated by. Due to the eccentric distance between the pump shaft 4 and the piston 3, the bearing of the pin 3.1 to the support ring 7 and the pivotal attachment by the swinging vanes 12,
Is pressed against the wall of the pump casing 1 with a narrow seal gap of several micrometers, and moves along the inner circumference of the pump casing 1. In this case, the piston center point circulates on one circular orbit centered on the rotation axis of the pump shaft 4, and the piston 3 makes a complete swing. At that time, the working medium passes through the pump inlet 16 and the piston 3
Is sucked into the pump suction chamber partitioned from the pressure chamber by the rocking vane 12 and the seal gap between the pump casing wall. The circumferential movement of the seal gap in response to the rotation of the pin 3.1 causes the sizes of the suction chamber and the pressure chamber to change periodically, and the working medium is discharged through the pump outlet 17. At that time, joint pin 1
3 is an outer end of the swinging vane 12, which moves on a short arc centered on the rotation axis of the rotary joint 14. in this case,
Due to the transmission connection between the pump casing 1 and the piston 3, the joint pin 13 and the rotary joint 14 of the oscillating vane 12 produce only limited movement in a narrow range, and the pump shaft 4 has a high rotational speed. No, the turning speed generated at that time is low. The pump is therefore particularly advantageous since it is designed as a dry rotor and does not require repeated lubrication. Rather, it is sufficient if the material pair in the joint pin 13 and the rotary joint 14 is lubricated once with solid lubricant and by itself has good emergency rotation properties.

Suitable plastics, for example pistons, casings and bearing covers, which have dry rotational properties, in particular injection-moldable, such as polyethylene, polypropylene,
Whereas the shaft and the eccentric body are made of commercially available tough steel while it is made of polyamide or the like, it has been found advantageous in terms of production technology.

On account of the forcible guidance between the piston 3 and the pump casing 1 and the provision of the sealing gap, no appreciable wear of the components occurs and it is customary in known displacement machines. There is no need for oil lubrication. By coating the support ring 7 with a suitable dry lubricant, which is reliably ground during the break-in of the components, the components forming the seal gaps can be manufactured with sufficiently narrow tolerances and are defined. It is possible to operate with sufficient certainty in the defined output range, especially in the achievable negative pressure.

FIG. 3 shows a modified embodiment of the piston 3 of the oscillating piston pump shown in FIG. In FIG. 3, instead of the joint pin, the joint socket 23
Is integrally formed on the outer circumference of the support ring 7, and in the joint socket 23, a first one provided at one end of a swing vane 12.1 connecting the piston 3 and the pump casing 1 is connected. The joint 24 is fitted. As in the case of the embodiment shown in FIG. 2, the second joint 25
Is located in a joint socket provided in the pump casing 1. In this embodiment, both ends of the swinging vane 12.1 are constructed symmetrically with respect to the first and second joints 24, 25 and are therefore suitable for mass production.

Accordingly, a displacement pump capable of providing the required vacuum for a particular loader, in particular a servo unit, in a motor vehicle is provided by the present invention, which displacement pump is a lubrication which is important for the useful life of the motor vehicle engine. It does not burden the oil circuit.

It should be noted that the present invention is not limited to the above-mentioned embodiments, although it should be noted that it is added. Rather, it can be implemented in various different ways without departing from the spirit of the invention, for example by driving the pump casing on the outer circumference by means of a toothed belt or a V-belt, the pin remaining stationary with the support pin. It is also possible to configure the pump to leave. At this point, it should be noted that the pump inlet and the pump outlet must be led out from the pin. Further, it is easy for those skilled in the art to adopt an appropriate slide bearing device in place of the above rolling bearing device.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an oscillating piston pump according to the present invention.

2 is a cross-sectional view of the oscillating piston pump shown in FIG.

FIG. 3 is a detailed sectional view of a modified embodiment.

[Explanation of symbols]

1 pump casing, 2 casing lid, 3
Piston, 3.1 pin, 3.2 Counter weight, 4 Pump drive shaft, 4.1 Coupling sleeve, 5 Fixed rolling bearing, 6
Movable rolling bearing, 7 support ring, 8 outer tube section, 8.1 radially inward shoulder, 9
Inner tube section, 9.1 Radially inward shoulder, 1
0,11 rolling bearing, 12 oscillating vanes, 12.
1 Swing Vane, 13 Joint Pin, 14
Rotary joint, 15 circumferentially recessed portion of pump casing, 16 pump inlet, 17 pump outlet, 18 arrow indicating rotation direction, 20 pin notch, 21 hub, 22 force generating member consisting of spring packet, 23 joint socket,
24 1st joint, 25 2nd joint

Claims (18)

[Claims] 1. A cylindrical pin (3.1) is eccentrically arranged in a cylindrical pump casing (1) and a cylindrical rigid support ring (7) which is closed in itself, is used for the pin (3.1). 3.1) has a width of the pump casing (1) which is rotatably supported thereon and which is axially closed by a casing lid (2), and which is on one busbar of the pump casing (1). Is provided with one swivel vane (12), one end of which is pivotally supported on one generatrix of the support ring (7) and the other end of which is pivotable, and the pump casing (1). ), And the length of the oscillating vane (12) is equal to 2 of the eccentric distance (ε) between the pump casing (1) and the support ring (7).
Greater than or equal to twice and less than or equal to twice the radius of the support ring (7), the pump casing (1) or the pin (3.1) is rotationally driven, In addition, the fixed one of the constituent members, that is, the pin (3.1) or the pump casing (1)
Has a pump inlet (16) and a pump outlet (17), an oscillating piston pump for generating a negative pressure in a gaseous medium. 2. The pump shaft (4) is arranged eccentrically in the pin (3.1) and is fixed in such a way that it cannot rotate relative to it.
The oscillating piston pump according to claim 1, which is associated with 1). 3. A pump shaft (1) in which the pump casing (1) is stationary and the pin (3.1) eccentrically arranged in the pump casing (1) is concentric with respect to the casing axis. Rotate around the axis of rotation of 4),
The oscillating piston pump according to claim 1 or 2. 4. A hub (2), the pump shaft (4) of which extends on the one hand to a longitudinal midpoint of the pump casing (1).
Oscillating piston pump according to any one of claims 1 to 3, which is mounted in 1) and, on the other hand, in a casing lid (2) which closes the pump casing (1). 5. Swing according to claim 4, characterized in that the bearing of the pump shaft (4) is designed as a rolling bearing (5, 6) and the inner races of the rolling bearing are axially clamped against one another. Dynamic piston pump. 6. The pin (3.1) rotates with the pin (3.1) and is provided by a notch (20) and / or a counterweight (3.2) arranged in the piston (3). An oscillating piston pump according to any one of claims 1 to 5, characterized in that it is mass-compensated with respect to the axis of rotation of the pin (3.1). 7. A piston (3) together with a pin (3.1).
The support ring (7) forming the part consists of two tube sections (8, 9) fitted axially in and out of each other, each tube section (8, 9) being composed of two tube sections (8, 9). ) At the opposite ends of each of the radially inwardly facing shoulders (8.1,
Oscillating piston pump according to any one of claims 1 to 6, having 9.1). 8. Both pipe sections (8, 9) of the support ring (7)
8. An oscillating piston pump according to claim 7, wherein the two are radially crimped to each other at both ends and have a mutual gap in the axially intermediate section. 9. The mutual gap width is at least 0.3 mm.
And an oscillating piston pump according to claim 8, which is less than 0.8 mm. 10. The support ring (7) comprises a disc spring (22).
Is supported on a pin (3.1) via two rolling bearings (10, 11) that are axially clamped to each other by a force generating member such as
Are arranged eccentrically with respect to the pump shaft (4) and the bearings (5, 6) for the pump shaft in the region of the longitudinal center of the piston (3). The oscillating piston pump according to item 1. 11. An oscillating vane (12) having a piston (3) at one end and a pump casing (1) at the other end mounted along one bus bar. 11. The oscillating piston pump according to claim 1, wherein the oscillating piston pump is curved in a convex shape and can be submerged in the circumferential recessed portion (15) of the pump casing (1). 12. A pump casing (1) has a circumferential recess (15) in which a pump inlet (16) and a pump outlet (17) are provided.
The oscillating piston pump according to claim 11, wherein the oscillating piston pump is arranged between 13. A swivel joint (14) for an oscillating vane (12) connected to the pump casing (1) comprises a pin (3.
Oscillating piston pump according to any one of claims 9 to 12, which is arranged in front of the pump inlet (16) in the direction of movement (18) of 1). 14. The longitudinal curvature of the oscillating vane (12) is substantially equal to the curvature of the piston (3) inside the oscillating vane and substantially outside the oscillating vane the pump casing (1). Equal to the curvature of
The oscillating piston pump according to any one of items 1 to 7. 15. The hub (2) of the pump casing (1).
1) Portion (4.1) of pump shaft (4) that has penetrated into the interior
5. The oscillating piston pump according to claim 4, wherein is a coupling sleeve. 16. A pump casing (1), casing lid (2), piston (3) and swing vane (12),
The sway according to any one of claims 1 to 15, wherein the surfaces forming a seal gap with each other are coated with a material, such as a solid lubricant, which has good adhesion and sliding properties. Dynamic piston pump. 17. The pump casing (1), the casing lid (2) and the piston (3) are made of injection-mouldable plastic with dry rotational properties, whereas the pump shaft (4), the support ring. The (7) and oscillating vanes (12, 12.1) are made of steel.
The oscillating piston pump according to any one of 1 to 15. 18. The oscillating vane (12.1) is constructed symmetrically and has joint pins (24, 25) at both ends, and one joint pin (24)
Inside the joint socket (23) provided on the outer periphery of the support ring (7) and at the other joint pin (25)
Swing piston pump according to any one of claims 1 to 17, characterized in that it is fitted in the recess of the pump casing (1).