JP2014066361A - Storage device including at least one spacing element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage device which prevents liquid pressure adhesion that inhibits pressure transition and thereby suppresses the occurence of noise.SOLUTION: A storage device 38 for a vehicle brake device includes: an accumulator cylinder 40; and an accumulator piston 42 which is guided in the accumulator cylinder 40. The accumulator cylinder 40 has a cylinder bottom part 48 facing the accumulator piston 42, and the accumulator piston 42 has a piston end part 66 facing the cylinder bottom part 48. At least one spacing element 72 is provided for maintaining a space 74 between the cylinder bottom part 48 and the piston end part 66. The individual spacing elements 72 are different members which are provided between the cylinder bottom part 48 and the piston end part 66.

Description

  The present invention is an accumulator device, particularly for a vehicle brake device, comprising an accumulator cylinder and an accumulator piston guided therein, and the accumulator cylinder has a cylinder bottom portion facing the accumulator piston. The accumulator piston has a piston end facing the cylinder bottom, and at least one spacing element is provided for maintaining a spacing between the cylinder bottom and the piston end. The present invention relates to a storage device. Furthermore, the present invention also relates to a method for using such a storage device in a vehicle brake device.

  This type of storage device is used in particular in vehicle brake devices and is used for intermediate storage of a pressure medium in the form of a fluid, in particular brake fluid. The pressure medium is returned from the wheel brake cylinder, or is supplied from the main accumulator of the vehicle brake device in a vehicle brake device equipped with an anti-lock brake system (ABS) and an electronic traveling stability program (ESP), for example.

  The accumulator includes an accumulator cylinder and an accumulator piston guided therein, and the accumulator piston defines an accumulator volume for the pressure medium. The pressure medium can be conveyed from the storage volume into the brake circuit when needed. As the storage volume decreases, the accumulator piston enters deeply into the accumulator cylinder.

  In accumulators with additional functions, it is often necessary to minimize the accumulator volume during operation and to have very little pressure medium in the accumulator. For this purpose, the accumulator piston has to enter the accumulator cylinder until it is locked at the cylinder bottom of the accumulator cylinder facing the piston end with its piston end. Both the cylinder bottom and the piston end have at least a sufficiently flat surface for reasons of manufacturing technology. Therefore, when the piston end is locked at the bottom of the cylinder, full contact occurs and the pressure medium is still present, so that the accumulator piston is simply decelerated away from the bottom of the cylinder. This action is called hydraulic bonding, which inhibits pressure transitions and produces undesirable and undesirable noise.

  An object of the present invention is to eliminate the drawbacks of conventional storage devices.

  According to the present invention, a storage device for a vehicle brake device in particular comprises an accumulator cylinder and an accumulator piston guided therein, the accumulator cylinder having a cylinder bottom facing the accumulator piston. The accumulator piston has a piston end facing the cylinder bottom, and is provided with at least one spacing element for maintaining a spacing between the cylinder bottom and the piston end. In this case, each said spacing element is a separate member provided between the cylinder bottom and the piston end.

  A separate member according to the invention provides a gap between the cylinder bottom and the piston end when the pump piston is fully advanced into the accumulator cylinder during operation, i.e. to the lock. At the same time, the locking provided by the spacing element according to the invention avoids locking by the entire surface, so that the piston end and the cylinder bottom may have at least a sufficiently flat piston end and cylinder bottom. This is advantageous because hydraulic adhesion is also prevented.

  With the spacing element according to the invention as a separate member, the pump piston and the pump cylinder can be manufactured with rotational symmetry so as to have a flat piston end face and a flat cylinder bottom face. This simple cutting manufacturing method is significantly less expensive than a production method for manufacturing a known storage device. Conventionally, in order to prevent hydraulic adhesion, for example, a strip end portion provided at the piston end portion has created a piston end portion appropriately configured in terms of geometric shape. Piston ends with such geometric shapes require a non-rotationally symmetric shape and can only be produced by non-cut molding methods such as casting, injection molding or cold forming. If the accumulator piston is manufactured by cutting for high precision requirements, the above geometry of the piston end must be formed by an expensive manufacturing step such as milling. Conventionally, the non-rotationally symmetric shape of the bottom of the cylinder can be manufactured only by an expensive method.

  The separate member according to the invention is advantageous because it projects only slightly from the plane of the piston end face or cylinder bottom. The slight amount of protrusion is advantageous because it provides a small space in which the fluid remains in the pump cylinder when the pump piston is locked.

  Especially in the case of a low-cost case where only one spacing element is provided, this spacing element is preferably arranged at least approximately in the middle between the cylinder bottom and the piston end. That is, it arrange | positions so that the tilting of the pump piston at the time of latching may be avoided. At least one spacing element is preferably provided, particularly preferably two spacing elements, and very particularly preferably three spacing elements. In this case, the pump piston presses the bottom of the cylinder statically with a specific force so that the force is balanced stably.

  Advantageously, the separate member is arranged fixedly on the bottom of the cylinder, in particular in a shape-constrained and / or frictionally fixed manner. The separate member is arranged so that the pump piston is subjected to pressure as the piston end pushes the cylinder bottom. The cylinder bottom is part of the pump cylinder, so that the pressure generated is also transmitted to the pump cylinder. The pump cylinder is usually formed by a hole provided in a hydraulic block used as a pump case. Thereby, the generated pressure is distributed throughout the hydraulic block, and the material load associated with this pressure can be kept relatively small. This has the advantage that the lifetime of the storage device according to the invention is particularly long.

  As an alternative or in addition, a separate member is arranged fixedly at the piston end, in particular in a shape-constrained and / or frictional connection with the piston end. Thus, the piston end constructed in accordance with the present invention provides a pump piston that can be easily retrofitted with conventional accumulators when necessary, and as a result also prevents hydraulic bonding.

  Furthermore, according to the invention, the separate member is preferably configured in the form of a sphere, in particular as a sphere, as a hemisphere and / or as a crown. The spherical shape advantageously provides a spacing element without corners and edges, and the fluid can pass by this spacing element during operation without significant hindrance. Furthermore, when the pump piston is locked, a point-like contact is provided between the spherical shape of the individual spacing elements and the abutment surface attached to the spacing elements, so that the fluid flows easily by the spacing elements. be able to. The attached abutment surface is the end surface of the piston when a separate member is disposed in a fixed position on the bottom of the cylinder. When a separate member is placed at the piston end, the attached abutment surface is the cylinder bottom.

  It is particularly advantageous if at least three spherical separate members are provided as spacing elements. This is because the pump piston is advantageous because it does not tilt when locked to the pump cylinder. Such tilting may occur when one or two spherical spacing elements are provided. However, at least three spherical spacing elements whose height and angular positions are aligned are uniquely identified statically in the pump cylinder when locked, i.e. in the locked position. Allows piston position.

  Furthermore, advantageously, the separate member is formed of a material that is harder than its associated abutment surface. That is, it is configured such that upon locking, a separate member enters at least slightly into its associated abutment surface so that a stable locking position is provided. In particular, when the separate member is a sphere, the first point-like contact occurs during locking, and this point-like contact increases continuously depending on the load, increasing the load resistance. Is formed. Here, Hertz's law of pressure action is utilized.

  Furthermore, the accumulator cylinder preferably has a longitudinal axis, and the storage device according to the invention is preferably provided with at least two spacing elements with different distance radii from the longitudinal axis. That is, the at least two spacing elements are arranged at different distances from the longitudinal axis. This is particularly advantageous because during operation, the pump piston not only performs a translational reciprocation, but also rotates about its longitudinal axis. This rotational movement results in a contact point located on a circle with a corresponding distance radius about the longitudinal axis on the abutment surface associated with the individual spacing elements. If a plurality of spacing elements having the same distance radius are provided, all the contact points exist only on one circle of the contact surface. If the distance radii of the at least two spacing elements are different according to the invention, different circles are generated at their contact points. This is advantageous because the wear of the attached abutment surface is particularly reduced.

  In addition, the separate member is preferably arranged in an attached withdrawal part, from which the separate member projects slightly to maintain the spacing between the cylinder bottom and the piston end. The attached pull-out part is advantageous because it can be easily formed using a punch. Pump cylinders or pump pistons can be produced rotationally symmetrically at low cost by cutting and then or simultaneously drilling to form the attached withdrawal section.

  Advantageously, the attached withdrawal part is provided at the bottom of the cylinder, so that the attached withdrawal part can be drilled together with the supply and discharge holes formed in the cylinder bottom of the storage device as well. This saves work and time, and thus costs. Further, the cylinder bottom is a component part of the pump case which is usually a hole provided in the hydraulic block as well. The cylinder bottom, together with the hydraulic block, encloses a relatively large amount of material, so that at least the cylinder bottom and thus the pump case is hardly molded when forming the withdrawal part.

  As an alternative or in addition, an individual associated withdrawal is provided at the piston end, in which the individual spacing elements are arranged.

  Advantageously, the separate member is press-fitted into the attached withdrawal part. This press-fit provides a particularly simple frictional connection between the separate member and the material surrounding the withdrawal part.

  In addition, the separate member is preferably crimped to the material surrounding the attached withdrawal. By caulking, the separate members and the material surrounding the withdrawal part are slightly plastically deformed, so that they are connected in a particularly stable and non-removable frictional and shape-constrained manner.

  The invention is also correspondingly directed to the use of such a storage device according to the invention in a vehicle brake device. In general, a vehicle brake device is provided that allows a particularly stable operation with very low cost and no hydraulic adhesion.

  Next, several embodiments of the solution according to the present invention will be described in detail with reference to the accompanying drawings.

It is a figure which shows a part of hydraulic circuit diagram of the vehicle brake device provided with the 1st example of the storage device by a technical level. FIG. 2 is a detailed view of FIG. 1. It is a longitudinal cross-sectional view of the 2nd example of the storage device by a technical level. 1 is a longitudinal sectional view of a first embodiment of a storage device according to the present invention. It is a longitudinal cross-sectional view of 2nd Embodiment of the storage device by this invention.

  FIG. 1 shows a vehicle brake device 10. The vehicle brake device includes a brake pedal 12 that can be operated by the driver of the four-wheel vehicle to which it belongs. The brake pedal 12 acts on the brake booster 14 and can be used to generate pressure in the fluid in the form of brake fluid in the attached brake master cylinder 16 using the brake booster. The brake master cylinder 16 is connected to various fluid pipes 18, by means of which the switching valve 20, the pump element 22 with the attached drive motor 24, the left rear suction valve 26, the right front suction valve 28, the left The rear discharge valve 30, the right front discharge valve 32, the left rear brake cylinder 34, and the right front brake cylinder 36 are selectively fluidly coupled to each other. Further, a storage device 38 for intermediate storage of brake fluid is connected to the fluid pipe 18.

  As for the storage device 38, FIG. 2 shows a first conventional example in a schematic principle diagram, and FIG. 3 shows a second conventional example in a more strict principle diagram. The accumulator 38 includes a glass-like, cylindrical accumulator cylinder 40, and an accumulator piston 42 is supported in the accumulator cylinder so as to be displaceable. The accumulator piston 42 is sealed on the inner surface of the accumulator cylinder 40 in a liquid-tight but simultaneously displaceable manner using a piston seal 44 that is fixedly positioned on the accumulator piston 42. The piston spring 46 pushes the accumulator piston 42 that is displaceably supported in this manner into the glass shape of the accumulator cylinder 40, and thereby intermediately accumulates brake fluid in a pressurized state in the accumulator cylinder. A pressure chamber is formed.

  The glass-shaped bottom surface of the accumulator cylinder 40 facing the accumulator piston 42 is a cylinder bottom 48. The cylinder bottom 48 is provided with a supply hole 50 for taking in brake fluid into the storage device 38, and the storage device is formed with a valve 52 for selectively opening and closing the supply hole 50. For this purpose, the valve 52 comprises a valve seal 54 which is pressed against the valve seat 58 in the direction of the accumulator piston 42 by a valve spring 56. The valve seat 58 is integrally formed with a valve seat body (not shown), and surrounds a valve hole corresponding to the supply hole 50 in this conventional example.

  The cylinder bottom 48 is further provided with a discharge hole 60 through which the brake fluid can be discharged from the storage device 38. The discharge hole 60 and the supply hole 50 both extend in parallel to the longitudinal axis 62 of the storage device 38 in the longitudinal direction.

  The cylinder bottom 48 is molded with the cylinder bottom 64 and is locked at its piston end 66 when the accumulator piston 42 runs into the accumulator cylinder 40. The piston end portion 66 also has a flat surface as the piston end surface 68. As a result, the piston end surface 68 comes into full contact with the cylinder bottom surface 64 when locked. Full contact may cause so-called hydraulic adhesion in cooperation with the brake fluid. This means that when the accumulator piston 42 starts running, the piston end surface 68 simply decelerates away from the cylinder bottom surface 64 and is thus separated again, so that the hydraulic operation is generally irregular and sometimes interrupted. .

  Such undesirable hydraulic adhesion during operation is advantageously avoided in the storage device 38 according to the invention of FIGS. 4 and 5, so that a stable hydraulic operation is achieved.

  FIG. 4 shows a first embodiment. In this embodiment, three withdrawal portions 70 are formed in the cylinder bottom portion 48, and one of the withdrawal portions 70 has a longitudinal section. It is shown in the figure. These three punched-out portions 70 are advantageous because they are cut and formed together with the supply holes 50 and the discharge holes 60 in a single manufacturing process, saving time and cost.

  One spacing element 72 in the form of a sphere is press-fitted as a separate member into each of the three drawing-out portions 70. Of these three separate members, the illustrated longitudinal section shows two spheres that protrude slightly from the flat cylinder bottom 64 at the same height. The flat piston end face 68 is configured to be locked to the spacing element 72 when the accumulator piston 42 enters, and the spacing element 74 maintains the spacing 74 with respect to the flat cylinder bottom surface 64. The spacing 74 is advantageous because it prevents the hydraulic adhesion described above. Furthermore, since the individual spacing elements 72 are spherical, it is advantageous that the brake fluid flows by these spacing elements with almost no hindrance.

  In this embodiment, the piston end surface 68 is a contact surface for the spherical spacing element 72, and the spacing element is made of a material harder than the piston end 66. The first point contacts of the individual spacing elements 72 when locked to the piston end face 68 are configured to expand into surface contact with increasing pressure load. Advantageously, the individual spacing elements 72 penetrate slightly into the piston end 66 so that the locking of the accumulator piston 42 is totally buffered. Furthermore, the individual spacing elements 72 are pressed against the piston end face 68 during the life of the storage device 38. The pressing force is along a circle on the piston end face 68 because rotational movement of the accumulator piston 42 occurs around the longitudinal axis 62 during operation.

  According to the invention, the individual spacing elements 72 are arranged at different distances in the radial direction from the longitudinal axis 62. Illustrated are two spacing elements 72 with a first distance radius 76 and a second distance radius 78 from the longitudinal axis 62, where the first distance radius 76 is greater than the second distance radius 78. Also short. Further, the third spacing element 72 not shown has an associated third distance radius (not shown), which is a first distance radius 76 and a second distance radius 78. Is different. Due to these different distance radii, different circles on the piston end face 68 are utilized as abutment surfaces during locking, so that the pressure load on the piston face 68 is distributed. This is particularly advantageous as a slight material wear and a long lifetime are achieved in this way.

  FIG. 5 shows a second embodiment that includes all the elements of the first embodiment described above. The difference from the first embodiment is that the third drawing-out portion 70 is formed in the piston end portion 66. The three attached separate members are inserted there as interference elements 72 by interference fit and project from the flat piston end face 68 at the same height. When the accumulator piston 42 enters, the spacing element 72 is pressed against the flat cylinder bottom surface 64 as an abutting surface together with the accumulator piston 42, whereby the spacing 74 is maintained during locking. Accordingly, it is advantageous to provide an accumulator piston 42 that can be easily retrofitted to the conventional accumulator 38 of FIG. 3 to prevent hydraulic bonding.

  In an alternative advantageous embodiment, the individual spacing elements 72 as separate members are caulked with the material surrounding the associated withdrawal section 70, thus providing a particularly stable, non-removable connection. The

  In other embodiments according to the present invention, individual spacing elements 72 or separate members, each provided in an associated withdrawal section 70, are located both in the piston end 66 and in the cylinder bottom 48.

  Furthermore, in an alternative embodiment of the invention, the spacing element 72 or the separate member is configured as a cylinder pin or in the form of a square that fits around the cylinder pin.

DESCRIPTION OF SYMBOLS 10 Vehicle brake device 38 Accumulator 40 Accumulator cylinder 42 Accumulator piston 48 Cylinder bottom 62 Accumulator cylinder longitudinal axis 64, 68 Abutting surface 66 Piston end 70 Pull-out portion 72 Spacing element 74 Spacing between cylinder bottom and piston end 76 , 78 Distance radius

Claims (10)

An accumulator cylinder (40) and an accumulator piston (42) guided therein, in particular a storage device (38) for a vehicle brake device (10), wherein the accumulator cylinder (40) A cylinder bottom (48) facing the accumulator piston (42), the accumulator piston (42) having a piston end (66) facing the cylinder bottom (48); In the storage device provided with at least one spacing element (72) for maintaining a spacing (74) between (48) and the piston end (66),
Storage device, wherein each said spacing element (72) is a separate member provided between said cylinder bottom (48) and said piston end (66).   The accumulator according to claim 1, wherein the separate member is arranged fixedly on the cylinder bottom (48).   The accumulator according to claim 1, wherein the separate member is arranged fixedly on the piston end (66).   The accumulation | storage device as described in any one of Claim 1 to 3 with which the said separate member is comprised by the spherical form.   5. The storage device according to claim 1, wherein the separate member is made of a material harder than its associated abutment surface (64, 68).   The accumulator cylinder (40) has a longitudinal axis (62) and is provided with at least two spacing elements (72) with different distance radii (76, 78) from the longitudinal axis (62). The storage device according to any one of 1 to 5.   Storage device according to any one of the preceding claims, wherein the separate member is arranged in an attached withdrawal part (70).   8. The storage device according to claim 7, wherein the separate member is press-fitted into an attached withdrawal part (70).   8. A storage device according to claim 7, wherein the separate member is caulked with the material surrounding the attached withdrawal section (70).   10. A method of using the storage device (38) according to any one of claims 1 to 9 in a vehicle brake device (10).

Images