EP2217808A1

EP2217808A1 - Guide ring for a piston pump, and piston pump

Info

Publication number: EP2217808A1
Application number: EP08804583A
Authority: EP
Inventors: Juergen Haecker; Rene Schepp; Norbert Alaze
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2007-11-05
Filing date: 2008-09-23
Publication date: 2010-08-18
Also published as: DE102007052664A1; WO2009059841A1; US20100266427A1; CN101842589A; CN101842589B

Abstract

The invention relates to a guide ring (1) for a pump piston (4) that can be axially adjusted back and forth, or a pump rod of a piston pump (2). The invention provides for the guide ring (1) to be configured as a radial damping element for damping radial impacts of the pump piston (4) or of the pump rod. The invention further relates to a piston pump (2) having such a guide ring (1).

Description

description

title

Guide ring for a piston pump and piston pump

State of the art

The invention relates to a guide ring according to the preamble of claim 1 and a piston pump according to the preamble of claim 8.

Piston pumps are used in hydraulic vehicle brake systems of motor vehicles and often referred to as return pumps. They serve in a slip control to selectively lower or increase the brake pressure in the wheel brake cylinders in order to regulate the brake pressure in the wheel brake cylinders can.

In known piston pumps there is the problem that the tightness of the piston pump in a wide temperature range, in particular up to temperatures around -30 ⁰ C must be ensured in order to avoid that brake fluid escapes from the brake system and / or that sucked air into the brake system becomes. This problem is described, for example, in DE 10 2005 046 048 A1. At low temperatures, a crescent-shaped gap arises between the pump piston or the pump rod of the piston pump and a ring seal due to radial impacts of the pump piston or the pump rod, through which brake fluid can escape from the brake system. The gap formation is due to the low flexibility of the ring seal at low temperatures and high load speeds of the pump piston or the pump rod. To solve the problem, DE 10 2005 046 048 A1 proposes to use a two-part ring seal which has an abrasion-resistant outer skin and an inner core made of a cold-flexible material. Axial between the two-part annular seal and an eccentric in the known piston pump, a guide ring for guiding the piston and a support ring are arranged, the latter prevents the insertion of the seal in the guide gap between the pump piston and the pump rod and the guide ring.

DISCLOSURE OF THE INVENTION Technical Problem

The invention has for its object to propose an alternative solution to avoid leakage of the piston pump at low temperatures and high load speeds. In particular, leaks should be reliably avoided even with the usual one-material ring seals.

Technical solution

This object is achieved by the use of a guide ring with the features of claim 1 and with a piston pump having the features of claim 8. Advantageous developments of the invention are specified in the subclaims. All combinations of at least two features disclosed in the description, the claims and / or the figures fall within the scope of the invention.

The invention is based on the idea of implementing a guiding principle enforced by the pump piston or the pump rod. ring for guiding the piston in such a way that it dampens the radial deflection movements of the pump piston or of the pump rod, which is due, for example, to a radial force component exerted by an eccentric on the pump piston or the pump rod. Characterized in that the radial shocks of the pump piston or the pump rod are damped by the guide ring, in particular such that the speed of the deflection reduced and / or the amplitude of the radial shocks is / is minimized, it is a preferably axially adjacent to the guide ring arranged ring seal possible also to follow the radial deflection movements, ie the radial impacts of the pump piston or the pump rod, even at low temperatures and a high axial load speed of the pump piston or the pump rod. As a result, in turn, a permanent contact of the ring seal is ensured to the pump piston or to the pump rod, which in turn avoids the formation of a crescent-shaped gap between the pump piston or the pump rod and the ring seal or the size of a sickle gap is at least minimized. The inventive design of the guide ring has the advantage that even with conventional ring seals a seal of the high pressure region of the pump with respect to a low pressure region, in particular an eccentric, can be ensured. Of course, the tightness can be further improved if an annular seal described in DE 10 2005 046 048 A1 is provided in addition to a guide ring formed according to the concept of the invention.

Of particular advantage is an embodiment of the damping in the radial direction of the guide ring, wherein the damping by the provision of at least one circumferential, in Radial direction elastic lip is realized. In this case, the lip serves as a resilient damping means in the radial direction, which reliably damps radial deflection movements of the pump piston or the pump rod. Instead of providing a lip which extends over the entire circumference of the guide ring, an embodiment is provided in which at least two lip sections or spring elements which are spaced apart from one another in the circumferential direction and which preferably abut the pump piston are provided for radially damping deflection movements of the pump piston or the pump rod are.

Of particular advantage is an embodiment in which the inner diameter of the at least one lip in the unassembled state, at least in one region, preferably in a free end region, is smaller than the outer diameter of the pump piston or the pump rod. As a result, a tight contact of the lip is realized on the pump piston or on the pump rod. In such an embodiment, the first lip not only has the function of a damping element, but it also serves as a wiper ring for stripping dirt particles, which are registered in particular from the direction of a Exzenterraums. The lip thus effectively prevents penetration of dirt particles to the ring seal whose life is thereby increased due to reduced wear. In contrast to known guide rings, a guide clearance between the pump piston or the pump rod and the guide ring, at least between the lip of the guide ring and the pump piston, is avoided by the close fitting design of the guide ring on the pump piston or on the pump rod. In a further development of the invention is advantageously provided that the guide ring has at least one second, in particular circumferential, resilient in the radial direction lip. In this case, the two, in particular circumferential, lips are preferably arranged spaced from one another in the axial direction in order to realize optimum guidance of the pump piston or pump rod and simultaneous damping of radial deflection movements of the pump piston or the pump rod. In addition, such an embodiment of the guide ring has the advantage that on a hitherto used support ring, which is arranged axially between the ring seal and the guide ring to a retraction of the seal in a guide gap between the guide ring and the pump piston or the To prevent pump rod, can be omitted if necessary, since the second lip takes over the task of the support ring.

Of particular advantage is an embodiment in which the two lips are arranged pointing with their free, circumferential end edges in opposite axial directions, it being within the scope of the development that the end edges are additionally inclined in the direction of the pump piston or in the direction of the pump rod , In particular, in such an embodiment, the retraction of the annular seal is advantageously avoided in a region between the radial guide ring and the pump piston or the pump rod.

Preferably, the second, in the radial direction resilient, preferably circumferential, lip is formed such that its inner diameter in the unassembled state is smaller than the outer diameter of the pump piston or the pump rod to a close concern of the guide ring or to ensure the second guide lip on the pump piston or on the pump rod.

Particularly preferred is an embodiment in which the guide ring is formed from a, in particular high-strength, thermoplastic material, so that on the one hand the management task and on the other the damping effect can be safely met. It is particularly preferred if the guide ring is produced as a one-piece injection molded part from a high-strength thermoplastic material. The thermoplastic material should be chosen such that it does not lose its damping, ie in the radial direction (slightly) resilient, even at temperatures around -30 ⁰ C, effect.

The invention also leads to a piston pump with a previously described guide ring, wherein the guide ring is preferably fixed by means of a press fit in a pump bore in a hydraulic block.

Preferably, the guide ring is arranged axially between an eccentric in which an eccentric is driven in rotation, and a ring seal. It is particularly advantageous if the guide ring is equipped with at least one, preferably circumferential, resilient in the radial direction lip, which is arranged with its free end edge pointing in the direction of the eccentric chamber. In this embodiment, in addition to the damping function, the first lip receives a dirt scraping function which prevents the ingress of dirt particles into a region between the ring seal and the guide ring. This leads to a longer life of the ring seal. In a further development of the invention is advantageously provided that the guide ring has at least one second resilient in the radial direction lip which is arranged with its free end edge pointing in the direction of the ring seal. As a result, it may be possible to dispense with a support ring axially between the ring seal and the guide ring.

Brief description of the drawings

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. These show in:

1 is a perspective view of a guide ring for a piston pump,

2 is an enlarged longitudinal sectional view of the guide ring of FIG. 1,

Fig. 3: a detail of a piston pump with a guide ring according to FIGS. 1 and 2 and

4: a detail enlargement from FIG. 3.

Embodiments of the invention

In the figures, the same components and components with the same function with the same reference numerals are marked. 1 and 2, a possible embodiment of a guide ring 1 for a piston pump 2 shown in Figs. 3 and 4 is shown.

The guide ring has a longitudinally stepped guide section whose inner diameter D _F corresponds to the outer diameter D _{A of} an axial reciprocating pump piston 4 of the piston pump 2 shown in FIG. 3 plus a minimum guide clearance. Axially to the guide portion 3 is adjacent to a circumferential lip 5, which extends from the guide portion 3 in both the axial direction and in the radial direction inwardly. A minimum inner diameter D _{Σ of} the lip 5 in the region of its free end edge 6 is dimensioned smaller in the illustrated, unassembled state than the outer diameter D _{A of} the pump piston 4 (see FIGS. 3 and 4). This ensures that the lip 5, at least in the region of its end edge 6, permanently on the pump piston 4, this surrounds, rests.

As is apparent from FIG. 2, the inner diameter of the lip 5 in the axial direction, starting from the inner diameter D _{F of} the guide section 3 to the inner diameter O ₁ shown in FIG. 2, is reduced steadily in the region of the circumferential end edge 6.

Since the guide ring 1 is formed of a high-strength thermoplastic material, the guide ring 1 in the region of the guide portion 3 is rigid and incompressible. Due to the weakening of the material in the end region, ie by the provision of the lip 5, the guide ring 1 receives in the region of the lip 5 a damping property (effect) for radial deflection movements of the pump piston 4. In other words, serves the guide ring 1 due to the provision of the radially resilient lip 5 as a damping element for radial shocks of the pump piston 4, which are due to radial force components resulting from the rotary movement of the eccentric 7 shown in Fig. 3.

Not shown is an embodiment in which in addition to the first lip 5, a second lip is provided which is formed on the first lip 5 opposite axial end of the guide portion 3. This, not shown, second lip is preferably formed mirror-symmetrically to the first lip 5 and prevents retraction of a ring seal 8 shown in Fig. 3 in a region radially between the guide portion 3 of the guide ring 1 and the pump piston. 4

FIGS. 3 and 4 show the installation situation of the guide ring 1 in a piston pump 2. The latter is arranged in a hydraulic block 9, in which except the piston pump 2, not shown components of a slip control hydraulic vehicle brake system, such as solenoid valves, check valves and hydraulic accumulator, housed and hydraulically interconnected. The hydraulic block 9 forms a pump housing of the piston pump 2. In this hydraulic block 9 a multi-stepped pump bore 10 is arranged.

The pump piston 4 of the piston pump 2 protrudes with its in the drawing plane left end face 11 in an eccentric 12 in, in which the eccentric 7 is rotatably driven about a perpendicular to the longitudinal extent of the pump piston 4 arranged axis of rotation. The eccentric 7 lies with its outer periphery on the end face 11 of the pump piston. 4 and applied to this with an adjusting force in the axial direction. The radial force component exerted by the eccentric 7 on the pump piston 4, which endeavors to deflect the pump piston 4 in the radial direction, is received or intercepted, at least in part, preferably completely, by the lip 5 of the guide ring 1.

On the eccentric 12 facing away, a Verdrängerraum 13 facing end face 14 is a Kunststoffdicht- element 15 is arranged, which seals the displacement chamber (high pressure side) against a suction side (low pressure side) of the piston pump 2. For this purpose, the sealing element 15 is arranged radially between the pump piston 4 and a bush 16. The bush 16 is fixed with a press fit in the pump bore 10.

For the pump inlet in the pump piston 4, an axially extending, end-side blind hole 17 is introduced, which is crossed near its bottom of transverse bores 18 gene. The blind bore 17 and the transverse bores 18 communicate with inflow bores 19 in the hydraulic block 9.

At the displacement chamber side end of the pump piston 4, a check valve is provided as the inlet valve 20. The inlet valve 20 has a valve ball 21, which cooperates with a conical inlet valve seat 22 on the pump piston 4. A closing spring 23 which is supported in the axial direction at one end on a plastic housing 25 of the inlet valve 20 and the other end on the valve ball 21, the valve ball 21 acts in the closing direction on the inlet valve seat 22. The plastic housing 25 of the inlet valve 20 is provided by a return spring for the Pumpenkol- ben 4 in the axial direction against the sealing element 15 spring force. The return spring 26 is received in the displacer 13.

At the end of the displacer 13 is also designed as a check valve outlet valve 27 is arranged with a valve ball 28 which is spring-loaded by a closing spring 29 on an internally tapered valve seat 30 on the bushing 16. In this case, the closing spring 29 is supported axially on a closure cover of the piston pump 2. When the outlet valve is open, hydraulic fluid (brake fluid) can flow out of the displacement chamber via a radial duct (not shown) into an annular space 32 radially outside the bush 16 and from there into outflow ducts 33.

In the enlarged view of FIG. 4, the exact mounting position of the guide ring 1 can be seen. The guide ring 1 is arranged with a press fit in the stepped pump bore 10, wherein the resilient in the radial direction, circumferential lip 5 is directed in the direction of the eccentric 12. The lip 5 dampens radial adjustment movements of the pump piston 4, wherein the lip 5 rests radially outwardly directly fully circumferentially on the pump piston 4. In contrast, a minimal guide play is provided between the guide section 3 of the guide ring 1 and the pump piston 4. Axially between the guide ring 1 and the ring seal 8, a support ring 24 is provided, which sits firmly on the pump piston 4. This prevents penetration of the ring seal 8 in the guide gap between the guide portion 3 and the pump piston 4. Is in addition to the first lip 5 a second, in the direction of Ring seal 8 pointing lip provided, if necessary, can be dispensed with such a support ring 24.

Claims

claims

1. guide ring for an axially reciprocally adjustable pump piston (4) or a pump rod of a piston pump (2),

characterized,

the guide ring (1) is designed as a radial damping element for damping radial shocks of the pump piston (4) or the pump rod.

2. Guide ring according to claim 1, characterized in that the guide ring (1) has a first, in particular circumferential, resilient in the radial direction lip (5).

3. Guide ring according to one of claims 1 or 2, characterized in that the inner diameter of the first lip (5) in the unassembled state is smaller than the outer diameter of the pump piston (4) or the pump rod.

4. Guide ring according to one of the preceding claims, characterized in that the guide ring (1) has at least one second, in particular circumferential, resilient in the radial direction lip.

5. Guide ring according to claim 4, characterized in that the first (5) and the second lip are arranged pointing with their free end edges (6) in opposite axial directions.

6. Guide ring according to one of claims 4 or 5, characterized in that the inner diameter of the first lip (5) in the unassembled state is smaller than the outer diameter of the pump piston (4) or the pump rod.

7. Guide ring according to one of the preceding claims, characterized in that the guide ring (1) is formed from a, in particular high-strength, thermoplastic material.

8. Piston pump for a hydraulic vehicle brake system having a pump piston (4) or a pump rod which is or can be driven to an axial, reciprocating motion, wherein the pump piston (4) or the pump rod at least one guide ring (1) passing through is arranged, characterized in that the guide ring (1) is designed according to one of the preceding claims.

9. Piston pump according to claim 8, characterized in that the guide ring (1) is arranged axially between an eccentric chamber (12) and a ring seal (8).

10. Piston pump according to one of claims 8 or 9, characterized in that a first, resilient in the radial direction lip (5) of the guide ring (1) with its free end edge (6) in the direction of the eccentric chamber (12) is arranged facing.

11. Piston pump according to one of claims 9 or 10, characterized in that at least one second resilient in the radial direction of the lip guide ring (1) is arranged immediately adjacent to the annular seal (8).

12. Use of a guide ring (1) according to any one of claims 1 to 7 for damping a radial deflection movement of a pump piston (4) or a pump rod in a piston pump (2) for a vehicle brake system.