JPH04234585A - Internal gear pump for pressurized fluid - Google Patents

Abstract

PURPOSE: To provide a compact internal gear pump by providing such an arrangement that no rotor is provided while an eccentrically rotating external gear is incorporated, and the structure of an inlet chamber is improved so as to use the inlet as a feed-out chamber and a feed-in chamber in its entirety. CONSTITUTION: An internal gear 6 is fixed to the inside of a pump peripheral wall 1 of a pump casing by means of a thread fastening member 7, and a relatively small external gear 14 is rotatably provided to an true circle cylindrical eccentric body 11 which is rotatable around the pump axis as a center, and is meshed with the internal gear 6. Further, an inlet chamber 28 is connected on one side with an inlet passage 9, and on the other side with a charge chambers (crescent chambers) in the pump through a connecting passage in the eccentric body. The inlet chamber 28 is defined by a cutout formed in an end face of the eccentric body 11, and a connection opening 35 formed in the cutout is extended over a central angle which is measured at the pump axis 13 and which is larger than the sum of a pitch angle and the central angle of the crescent chambers 23 at the pump axis.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a gear pump.

0002

[Prior Art] Such a pump is DE-OS3448.
253 (pp-1372).

In this case, the external gear is supported eccentrically with respect to the pump axis in a notch in the rotor. The rotor is rotatably mounted in the space formed by the internal gear and is fixedly connected to the pump shaft, which serves to drive the rotor. The known pump has a cylindrical inlet chamber located in the end wall as an inlet, as well as a passage system in the rotor, which are connected to one another.

This configuration is advantageous only if the entire interior space formed by the tip circle of the internal gear is filled by the rotor (as far as this is outside the meshing area of the tooth profile).

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to configure an internal gear pump without a rotor but with an external gear that rotates eccentrically, and to connect the inlet to the teeth on the discharge side. The design is such that the entire engagement area of the inlet is not short-circuited with the inlet area and is therefore used in its entirety as a delivery chamber and a discharge chamber.

[0006]

The above object is achieved by the features of claim 1.

[0007]

According to the embodiment of the invention, an inlet chamber is obtained which rotates together with the eccentric, the inlet chamber being connected on the one hand directly or via an axial channel provided in the eccentric with the inlet channel; On the other hand, it is connected only to the crescent chamber of the pump, which rotates with the eccentric.

The teeth of the pump are preferably arranged in such a way that in each case a plurality of pairs of teeth mesh closely in the meshing region between the intersections of the tip circles and form a closed displacement chamber. It is configured. This interlocking area is closed in any case by the design of claim 1.

[0009] In the area of the filling chamber there may be another connection between the recess and the filling chamber. If in this case the pump is to be operated with a throttle on the suction side (so that the filling is no longer speed-dependent at a certain speed), a throttle is arranged in the inlet channel. It is also possible for the recess around the eccentric to be closed except for a narrow throttle opening even in the region of the filling chamber. In this case, the inlet is restricted on the one hand by the throttling resistance and, on the other hand, for a limited time (during which time the throttling opening of the notch engages in each case with one of the connecting openings of the external gear).
(opening the passage between the notch and the filling chamber). It is possible to precisely meter the oil flow into the pump and to precisely fix the rotational speed range in which a constant discharge rate occurs. Exposure of the sealing member 37 to pressure differences is avoided.

[0010] According to the configuration according to claim 3, it is avoided that the rotating force generated by the rotation of the external gear and the discharge zone acts on the drive shaft, resulting in curvature of the shaft and tilting of the external gear.

[0011] According to the configuration according to claim 4, good cooling and lubrication of the eccentric body which is exposed to heat and wear loads by the inner and outer sliding bearing parts is achieved.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pump casing is formed by a pump jacket 1 and end plates 2, 3, which overlap one another. The casing peripheral wall 1 has a perfectly circular cylindrical inner chamber, and an annular groove 4 is formed in the cylindrical inner peripheral surface. An internal gear 6 is fixed to the web 5 remaining on both sides. The entire package consisting of the housing jacket 1, the end plates 2, 3 and the internal gear 6 is held together by a screw connection 7. The screw connection 7 passes through the internal gear in the region of the tooth tip by means of a bore 8 .

[0013] The internal gear has internal teeth. The internal space of the pump is bounded by the tip circle 9 of the internal gear by internal teeth. A pin 10 is fixedly inserted into the end plate 3 with one end. The other end of the pin 10 projects into the inner chamber of the pump. An eccentric body 11 is rotatably supported on the pin 10. The axial width of the eccentric body is approximately equal to the axial widths of the casing peripheral wall 1 and the internal gear 6. The eccentric body has a perfectly circular cylindrical outer circumferential surface, and its central axis is indicated by reference numeral 12. The eccentric body rotates around the axis 13 of the pin 10 with an eccentricity E. An external gear 14 is rotatably supported on the eccentric body 11. The external gear 14 has external teeth. The eccentricity E of the eccentric body and the external teeth of the external gear are designed so that the external teeth of the external gear mesh with the internal teeth of the internal gear, and a tooth profile portion is formed.

Therefore, the tip circles 9 and 15 of the tooth profile intersect at rotating intersection points 21 and 22. As a result, on the inner circumferential surface of the addendum circle 9 of the internal gear, a meshing region is created between the intersection points 21 and 22 that rotates toward the side where the eccentricity E of the axis 13 is located, and on the other hand, the meshing region rotates toward the side where the eccentricity E of the axis 13 is located. On the opposite side there is a rotating crescent or filling chamber 23 of the pump.

The tooth profile portion is formed such that the teeth of the internal gear and the external gear closely mesh with the tooth surfaces between the intersection points 21 and 22 of the addendum circles 9 and 15. Therefore, the intersection 21,2
A plurality of displacement chambers are created in the meshing region between the two, which are sealed against each other and against the crescent chamber 23 on the side opposite to the eccentric side by contact of the tooth surfaces.

A drive shaft 16 is used to drive the pump. The drive shaft 16 is rotatably supported in the other end plate 2 concentrically with respect to the axis 13 of the pin 10, and its end ends approximately in line with the inner surface of the pump chamber. There is. Here, the drive shaft 16 forms an end surface, and a connecting piece 17 is eccentrically fixed to this end surface. This connecting piece 17
protrudes axially into the entrainment pocket 18, which is formed in the end face of the adjacent eccentric 11 in the eccentric region.

The pump has an approximately radial inlet passage 19 in the end plate 3 as an inlet. The entrance passage is distribution room 20
The distribution chamber concentrically surrounds the pin 10. The distribution chamber is formed as a perfect circular cylindrical notch in the end face of the end plate that limits the pump chamber. The radius of the distribution chamber is smaller than the radius FJ of the root circle of the external gear by the amount of eccentricity E.

Another perfect circular cylindrical notch is formed on the end surface of the end plate 2 on the opposite side of the eccentric body 11, concentrically with the central axis 12 of the eccentric body. This cutout is used as the entrance chamber 28. Distribution chamber 20 and inlet chamber 28 are connected to each other by a passage. The passage passes axially through the eccentric. These channels are preferably designed as grooves in the inner bore of the eccentric and are used for lubrication of the plain bearing of the eccentric on the pin 10 as well as for cooling the eccentric 11. The entraining pocket 18 is used as such a passage, so that it passes axially through the eccentric body 11 and its outer edge lies on a circumference with a radius slightly larger than the radius of the shaft. A plurality of such passages can also be provided. From Figure 2, 2
Two further such lubrication channels 29, 30 are found in the plain bearing area of the external gear. The lubrication passages are each offset by 60° in the circumferential direction of the eccentric body 11. Suitable passages can also be provided in the inner bore of the eccentric, so that these lubrication passages 2
The oil flow flowing through 9, 30 and entrainment pocket 18 provides a symmetrical distribution of the oil and at the same time hydrodynamic support of the eccentric. However, this oil flow also has the effect of cooling the eccentric body. This cooling effect is particularly important since the eccentric itself is rotatably supported in the inner bore and the outer peripheral surface is used as a rotatable support for the external gear.

The notch 28 is closed to the inner peripheral surface of the external gear by the remaining rib 34. This rib must extend substantially over the entire engagement range. In other words, the notch may reach the inner circumferential surface of the external gear only on the side opposite to the eccentric side of the eccentric bearing portion. This opening area is simply the range in which, at most, the central angle measured at the pump axis 13 is not greater than the sum of the pitch angle and the central angle measured at the pump axis 13 of the crescent chamber 23 (opening area). It may just extend over the entire length.

FIG. 2 shows that even in the open area the rib 34 has only a small connecting opening 35 in the form of a groove formed in the end face of the rib. This groove is on an axis of the eccentric that intersects the pump axis and the eccentric axis, but on the opposite side from the eccentric axis.

The external gear has a connecting groove 36 on the end face located in the radial plane of the notch 28. Each connection groove 3
6 connects each tooth bottom with the inner circumferential surface in the radial direction.

The outlet passage 24 is located radially in the housing jacket 2 and is connected to the circumferential groove 4 of the housing jacket. This circumferential groove is bounded on the inside by the outer circumferential surface of the external gear and forms an outer chamber.

[0023] The internal gear has at least one gear in each tooth groove area.
It has two exit holes 25. FIG. 1 shows that two outlet holes 25.1, 25.2 are arranged axially in each tooth groove. The outlet holes are each arranged in parallel radial planes. Each radial plane is covered by an elastic valve ring 26.1, 26.2, which covers all outlet holes in the vertical plane and is divided in the axial plane. One end of the valve ring is fixed, for example by a rivet, and the other end is freely movable. These valve rings 26.1, 26.2 act as check valves for each outlet hole.

Next, the operation will be described.

The drive shaft 16 is driven in a rotational direction indicated by 31. At this time, the connecting piece 17 engages in the entraining pocket of the eccentric and entrains the eccentric. This causes the external gear to perform a tottering movement within the inner chamber of the pump, and the external gear rotates in the direction indicated by 32 as a result of the meshing of its tooth profile with the tooth profile of the internal gear. The external gear and the tooth profile of the internal gear form a plurality of displacement chambers between the intersection points 21 and 22 of both addendum circles, and the displacement chambers continuously expand and contract. In the subsequent region, the displacement chamber expands until it opens and communicates with the oil-filled crescent chamber. The displacement chamber is reduced on the leading side of the external gear. The oil is therefore under pressure here. If the pressure in the displacement chamber exceeds the system pressure prevailing in the circumferential groove 4, here the valve rings 26.1 and 26.2 close to the outlet hole 2 due to the pressure difference.
5.1, 25.2, so that oil can flow out of the chamber.

As a result of the negative pressure generated on the inlet side, oil flows into the inlet passage 1.
Inhaled from 9. The oil first reaches into the distribution chamber 20. The distribution chamber is connected to the recess 28 by an entraining pocket 18 and/or a connecting channel 29 that passes axially through the eccentric. The connecting passage 29 is guided as a groove in the inner circumferential surface of the sliding bearing of the eccentric. This results in a good lubricating film in the area of the plain bearing of the eccentric 11, which serves both for lubrication and for hydrodynamic support.

As a result of the rotation of the eccentric body in the direction of rotation shown by arrow 31, the external gear rotates in the direction of rotation shown by arrow 32. The gear thus performs a relative movement with respect to the eccentric and the radial connecting opening 35 of the rib 34 of the eccentric. Therefore, the notch 28 and the crescent chamber of the pump (
An intermittent connection is formed with the filling chamber 23 via a connection groove 36 on the end face of the external gear. Connection opening 3
5 and/or the connecting groove 36 are dimensioned in such a way that they only provide a constricting connection. In addition, the amount of oil that has entered the filling chamber 23 is increased over a period of time depending on the rotation speed (in this time, the connection opening 35 and the connection groove 36
and are respectively aligned). The throttling action at this location prevents the sealing member 37 from being exposed to differential pressure.

The connecting opening 35 can also be made larger than in the illustrated example, so that the respective connecting grooves of the external gear are aligned with the connecting opening 35 of the cutout and thus between the cutout 28 and the filling chamber 23 . There is a constant connection. However, the dimensions of the connecting opening 35 are limited such that it in no way covers one of the closed displacement chambers of the engagement area. This results in a dead distance (T) in the discharge area of these displacement chambers.
otweg) is avoided and hydraulic efficiency is maintained or improved. The width of the connecting opening 35 may therefore be one pitch larger than the width of the crescent chamber 23, which is limited by the two tip circles. Here, crescent chamber 23, connection opening 3
5. The width of each pitch is measured as the central angle at the central axis 13 of the pump.

The pump can advantageously also be used as a pump which is throttled on the suction side. By restricting the amount of oil that is allowed to flow in, only a limited amount of oil is sucked in per unit of time. This time-limited suction amount is sufficient for complete filling of the pump up to a certain rotational speed. Therefore, until this rotational speed is reached, the pump discharge amount is proportional to the rotational speed. An increase in the rotational speed no longer results in an increase in the delivery volume. An increase in rotational speed is therefore not coupled with an increase in oil consumption. The pump is therefore particularly suitable for motor vehicle actuators whose oil requirements are independent of highly variable engine speeds.

As mentioned above, the throttling effect can advantageously be achieved by the narrow design of the connecting opening 35, the recess 28 and/or the narrow design of the connecting groove in the end face of the external gear. Alternatively or additionally, it is also possible to provide a throttle in the inlet channel 19, which restricts the amount of oil that flows through per unit of time.

Alternatively or additionally, the throttling effect can also be effected by means of a throttle (not shown) integrated in the inlet channel 19 or in front of the inlet channel.

[Brief explanation of the drawing]

1 is a sectional view including the axis of a pump according to the invention; FIG.

FIG. 2 is a cross-sectional view of the pump of FIG. 1;

[Explanation of symbols]

1 Casing peripheral wall 2, 3 End plate 4 Groove 5. Web 6 Internal gear 7 Screw connection member 8 holes 9 Tip circle 10 pin 11 Eccentric body 12 Central axis 13 Axis line 14 External gear 15 Tip circle 16 Drive shaft 17 Connecting piece 18 Entrainment pocket 19 Entrance passage 20 Distribution room 21, 22 intersection 23 Crescent room 24 Exit passage 25.1, 25.2 Exit hole 26.1, 26.2 Valve ring 27 Entrance surface 28 Entrance room 29,30 Lubrication path 31, 32 Arrow 33 Aperture 34 Rib 35 Connection opening 36 Connection groove

Claims (5)

[Claims] 1. An internal gear pump for hydraulic fluids, in which an internal gear (6) with internal teeth is arranged in a fixed position and forms a closed internal chamber, and an internal gear (6) with internal teeth forms a closed internal chamber. A relatively small external gear (14) is rotatable on a perfect circular cylindrical eccentric rotatable about the pump axis,
Moreover, it meshes with the internal gear, and the inlet is in the entrance chamber (2
8), and the inlet chamber is connected to the crescent chamber (23), which is the filling chamber of the pump, via the inlet passage (19) on one side and the connecting passage of the eccentric body (11) on the other side. In this, the inlet chamber (28) is a notch formed in the end face of the eccentric body, the notch has a connection opening (35) facing radially toward the inner circumferential surface of the external gear, and the connection The pump axis of the crescent chamber (23) rotating together with the eccentric, formed by the pitch angle and the tip circle on the side opposite to the eccentric side, as the center angle with the opening measured in the pump axis (13) Extending over a center angle smaller than the sum of the center angle measured in (13), and external gear (14)
is a connecting groove (36
), the internal gear pump for hydraulic fluids is characterized in that the connecting passage is located in the plane of the cutout. [Claim 2] The notch (28) is formed directly or on the eccentric body (1
1) is connected to a perfect circular cylindrical distribution chamber (20) adjacent to the end face of the eccentric body (11) through connection passages (18, 29) formed in the axial direction, and the distribution chamber is connected to the inlet passage. (19
), and the radius of the distribution chamber is smaller than the difference between the radius (FJ) of the root circle of the external gear and the eccentricity. 3. The eccentric (11) is rotatably supported on a pin (10) fixed and cantilevered in the casing and concentric with the pump axis; 3. The pump according to claim 1, wherein the drive piece (17) is connected to the pump shaft in a rotationally fixed manner by a drive piece (17) which engages in a drive pocket (18) of the eccentric. 4. A cutout (28) and a distribution chamber (20) are formed on each side of the eccentric body and are connected via axis-parallel passages (18, 29) provided in the eccentric body (11). and in particular, the axis-parallel passage (29) is connected to the pin (1).
0) the sliding bearing part of the eccentric body (11) on the top and/or
4. The pump according to claim 1, wherein the sliding bearing of the external gear (14) on the eccentric (11) is formed in the form of an axial groove. [Claim 5] The entrainment pocket (18) has a notch (28).
5. The pump according to claim 4, wherein the pump is used as an axis-parallel passage between the pump and the distribution chamber (20).