JP2001010483A - Pump unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high accuracy for circular rotation of a motor shaft and a pump shaft so that a joint non-rotatably interconnecting both shafts is formed with the requirement for a slight accuracy. SOLUTION: In this pump unit 10 having an electric motor 12 and a radial piston pump 14, a motor shaft 32 and a pump shaft 20 are supported by one common bearing 30 in order to save bearings. In order to compensate for alignment errors, the pump shaft 20 is non-rotatably connected to the motor shaft 32 via a joint shaft 44. In that case, the joint shaft 44 is non-rotatably brought into form engagement with the motor shaft 32 and the pump shaft 20 via a multi-edge contour 48, with a play of angles and an axial play.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump unit, in particular for a slip-controlled vehicle brake system, which is non-rotatably connected to an electric motor with a motor shaft via a non-switchable coupling. A pump having a pump shaft and driven by an electric motor, and a bearing disposed between the electric motor and the pump, wherein the pump shaft is directly rotatably supported by the bearing. About.

[0002]

2. Description of the Related Art Pump units of this kind are nowadays used not only for anti-lock control (ABS) but also for other functions such as traction control (ASR), cruise control (FDR), distance control (ECD) and the like. It is also increasingly used for brake pressure generation in electro-hydraulic (external) vehicle brake systems. These additional features double the operating time of the pump unit,
This increases the demand for durability of the pump unit. Furthermore, this has the additional function of starting the pump unit without the driver having to operate the brake. The noise that surprises the driver when the pump unit is started up and when it is operated may be irritating to the driver. This and the requirement to relieve the vehicle occupant of the noise annoyance as much as possible increase the demand for noise reduction of the pump unit. Therefore, especially when the pump of the pump unit discharges discontinuously as in a piston pump, for example, whereby the rotating part of the pump unit may generate vibration, the rotating part of the pump unit is reduced. It is important to support by vibration. At the same time, the bearings need to be released from mechanical stress, which in turn requires alignment.

[0003] From WO 98/53202 a slip-controlled vehicle brake system is known. The pump unit includes an electric motor and a pump, and the electric motor is fixed to the pump, and the pump is driven by the electric motor. The pump has a bearing arranged between the pump and the electric motor, in which the pump shaft is directly rotatably mounted. The motor shaft of the electric motor is separate from the pump shaft, and both shafts are non-rotatably connected to each other. Due to the non-rotatable connection, the motor shaft has a section with a multi-edge profile, a polygonal profile or a multi-tooth profile, which fits into the complementary inner profile of the pump shaft. Of the motor shaft,
The end section fitted in the pump shaft, together with the pump shaft,
It forms one non-switchable joint which is made non-rotatable by positive engagement. The motor shaft fitted into the pump shaft is rotatably mounted via this pump shaft indirectly in bearings arranged between the electric motor and the pump.

A disadvantage of this known pump unit is that the motor shaft, which is held only indirectly via a pump shaft in a bearing arranged between the electric motor and the pump, is supported with sufficient roundness accuracy. Therefore, it is necessary to form a highly accurate outer contour of the motor shaft and a highly accurate inner contour of the pump shaft. The manufacture of motor shafts and pump shafts is therefore expensive and expensive, and many defective products have to be estimated. In addition, in order to obtain sufficient circular rotation accuracy of the motor shaft supported only indirectly in the bearing via the pump shaft, the joint must not play, and the motor shaft must be mounted inside the pump shaft. It must be fitted without play. The disadvantage of this is that alignment errors between the bearings of the motor shaft, far from the pump, the bearings of the pump shaft, far from the motor, and the bearings located between the motor and the pump, can result in a misalignment of the motor shaft and the pump. This causes mechanical stress on the shaft, which in turn excites mechanical vibrations during rotation and increases bearing wear.

[0005] This problem is addressed by the removal of the bearings remote from the pump or the motor, but in this way the motor shaft is only supported on one side and the rotation of the motor does not occur. The disadvantages are that the part that oscillates vibrates or that the pump shaft is only supported on one side.

[0006]

An object of the present invention is to solve this problem.

[0007]

According to the present invention, a pump unit of the type described at the outset is arranged between an electric motor and a pump as described in the characterizing part of claim 1. The motor shaft is also directly rotatably supported by the provided bearing, and the joint is provided with a joint shaft which is axially spaced from the motor shaft and the pump shaft. The rotation is prevented by the form engagement at two points, which is also solved by engaging with angular play and axial play.

[0008]

According to the above-described structure of the present invention, high roundness accuracy of the motor shaft and the pump shaft can be obtained, and as a result,
A joint connecting the two shafts non-rotatably to one another can be formed with little precision requirements. The joint is formed to have play. This simplifies the assembly of the motor shaft and the pump shaft, makes them cheap to manufacture, and reduces rejects.

The coupling of the pump unit according to the invention has a coupling shaft which is axially spaced from one another.
At the points, preferably at their end sections, non-rotatably engaging with the motor shaft and the pump shaft by means of form engagement, and at the same time with angular play and axial play with respect to the motor shaft and the pump shaft. have. This non-rotatable form engagement with angular play and axial play is formed, for example, by multi-edge contours, polygonal contours, multi-tooth contours and tongue or groove pins. The joint shaft is non-rotatably connected to the motor shaft and the pump shaft by shape engagement, and is rotatable to the side by a certain angle with respect to the motor shaft and the pump shaft and is slidable in the axial direction. Form a cardan shaft. This joint shaft causes an alignment error between the motor shaft and the pump shaft, not only an angle error but also a parallel displacement.
For example, it also compensates for axial displacement due to thermal expansion.
In particular, the production of pump unit couplings according to the invention is particularly expensive, since the inaccuracies of the couplings have no effect on the true circular rotation of the motor shaft or the pump shaft or on the vibration behavior of the rotating part of the motor. No accuracy requirements are imposed. Therefore, the motor shaft, the coupling shaft and the pump shaft can be manufactured at low cost, and the manufacturing accuracy may be low, so that there are few defective products. In addition, the motor shaft and the pump shaft are disposed between the electric motor and the pump without causing stress on the motor shaft and the pump shaft due to the alignment error caused by the manufacturing error of the three bearings of the conventional pump unit. Inside, the bearing is mounted externally on the end remote from the pump, and the pump shaft is mounted on the end of the bearing remote from the motor. According to the invention, this allows the pump shaft to be supported at its two ends and to be stably supported against the radial force of the pump, as well as the motor shaft at both ends. By supporting, it is possible to prevent vibration of the rotating part of the electric motor. This stress-free and vibration-free mounting of the motor shaft and the pump shaft reduces the operating noise and bearing wear of the pump unit.

Claims other than claim 1 describe advantageous configurations of the invention.

[0011] Less vibration, in short, avoid vibration
Or limited or damped bearings, in particular, a pump of a pump unit, such as, for example, a piston pump, may perform a non-continuous discharge (claim 3), so that the rotating part of the electric motor oscillates. It is advantageous in some cases.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiments.

The illustrated pump unit, generally designated 10, according to the present invention has an electric motor 12 and a pump 14, the pump being formed as a radial piston pump. The radial piston pump is mounted in a hydraulic block 16 forming a pump casing. The pump unit 10 supplies the brake fluid in a hydraulic vehicle brake device (not shown) to, for example, an antilock control, a traction control, a cruise control and an interval control (ABS, ASR;
FDR, ECD). Electric motor 12
Are screwed to the hydraulic block 16 by screws 18.

The radial piston pump 14 has a pump shaft 2
The pump shaft has an eccentric ring 22 non-rotatably press-fitted to the pump shaft. The eccentric ring 22 has a hole formed eccentrically with respect to its outer periphery, and the eccentric ring is press-fitted to the pump shaft 20 with this hole. A needle bearing 24 is arranged on the eccentric ring 22, and its running sleeve 26 bears on its end faces the two pistons 27 of the radial piston pump 14. Due to the rotational drive of the pump shaft 20, the piston is driven by an eccentric ring 22 in a known manner and reciprocated for the discharge of brake fluid. The pump shaft 20 is
Two ball bearings 28, 3 located on both sides of the eccentric ring 22
O is rotatably mounted in the hydraulic block 16 forming the pump housing. One ball bearing 3
0 is arranged between the radial piston pump 14 and the electric motor 12.

In this case, the ball bearing 30 disposed between the motor 12 and the radial piston pump 14 serves as a fixed bearing, and the ball bearing 28 remote from the motor 12 serves as a movable bearing, or vice versa. The ball bearing 30 disposed between the motor and the radial piston pump 14 can be formed as a movable bearing, and the ball bearing 28 remote from the electric motor 12 can be formed as a fixed bearing. What is a fixed bearing?
The bearing is press-fitted into a bearing receptacle in the pump casing 16, meaning that the pump shaft 20 is press-fitted in this bearing. This fixed bearing fixes the pump shaft 20 in the axial direction. The movable bearing means a bearing in which the bearing is pressed into a bearing receiving portion in the pump casing 16 and the pump shaft 20 is fitted in the bearing. This mobile bearing allows axial mobility of the pump shaft 20 for compensation for axial errors and thermal expansion.

The motor 12 is a conventional motor of known construction, as is known to those skilled in the art in a wide variety of embodiments. Therefore, a detailed description of the structure and function of the electric motor 12 will be omitted in the present invention.

The electric motor 12 has a motor shaft 32,
This motor shaft is separated from the pump shaft 20, and one end thereof is, similarly to the pump shaft 20, a ball bearing 30 disposed between the electric motor 12 and the radial piston pump 14.
It is supported within. Motor shaft 32 and pump shaft 20
Is inserted into one inner ring 34 of the ball bearing 30 disposed between the electric motor 12 and the radial piston pump 14 so that the pump shaft protrudes slightly deeper than the motor shaft.
In short, the two shafts 20, 32 are each received directly in the ball bearing 30 and are rotatably mounted. The motor shaft 32 is aligned with the pump shaft 20. One bearing is saved by the fact that the opposite ends of the motor shaft 32 and the pump shaft 20 are mounted together in one ball bearing 30. Shaft displacement is avoided by a common bearing in one ball bearing 30.

An end of the motor shaft 32 remote from the pump is connected to a motor bearing 3 inserted in a motor casing 38.
6 is rotatably supported. The motor bearing 36 is a plain bearing, which is formed as a sintered metal bearing, whose pores are filled with an aging-resistant lubricating oil for permanent lubrication.

Electric motor 12 and radial piston pump 14
Is inserted into the hydraulic block 16 forming the pump casing so as to slightly protrude. The motor 12 has a cylindrical cut-out 40 that is exactly adapted to the ball bearing 30, by means of which the motor causes the hydraulic block 12 of the ball bearing 30.
And is positioned on the hydraulic block 16 so as to be aligned with the radial pump 14.

Due to the non-rotatable connection between the pump shaft 20 and the motor shaft 32, the pump unit 10 according to the invention has a non-switchable joint 42, which has a joint shaft 44. The coupling shaft 44 is made from a hexagonal bar, the intermediate section 46 of which is milled to a relatively small diameter. Both end sections 48 of the coupling shaft 44
Have a hexagonal edge profile that can be formed into a crowning shape.

The mutually opposite end sections of the pump shaft 20 and the motor shaft 32 are formed as hollow shaft sections, which hollow shaft sections are complementary to the hexagonal edge contours of the coupling shaft 44, 52, in which case the hexagonal edge profile of the coupling shaft 44 and the pump shaft 20 and motor shaft 3
A play exists between the two hexagonal inner contours 50 and 52. The joint shaft 44 transmits the rotational motion of the motor shaft 32 to the pump shaft 20 by a hexagonal edge profile. This play between the coupling shaft 44 and the pump shaft 20 and the motor shaft 32 allows the coupling shaft 44 to pivot laterally by a certain angle like a Cardan joint, and Alignment errors with the motor shaft 32, as well as misalignments and angular errors, are compensated. The joint shaft 44 is axially slidably inserted into the hexagonal inner contours 50, 52 of the motor shaft 20 and the pump shaft 32, whereby the joint 42 is connected to the pump shaft 20 due to, for example, temperature expansion. Axial sliding with the motor shaft 32 is also compensated. Intermediate section 4 with relatively small diameter
6 is a joint shaft 44 in the motor shaft 32 and the pump shaft 20.
Does not hinder the turning of the vehicle.

To form the joint 42 as an elastic joint, the joint shaft 44 can be formed torsionally elastic with a small cross-section or diameter choice. The joint shaft 44 can be formed torsionally elastic, for example by fabrication from plastic, or as a steel / plastic composite part with a plastic-coated steel core or with an intermediate part made of plastic. it can. End section 4 with hexagonal edge profile of joint shaft 44
8 may also be coated with plastic or with a plastic hose which acts as a damping element as well as maintaining a non-rotatable connection by positive engagement between the pump shaft 20 and the motor shaft 32 Can also. With such an elastic configuration of the joint 42, when the radial piston pump 14 is driven, torque fluctuations caused by the discontinuous discharge type of the radial piston pump are buffered, and the motor shaft 32 of the electric motor 12 and the motor shaft 32, The vibration excitation of the part (mover winding, commutator) that rotates together with is reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view including an axis of a pump unit according to the present invention.

[Explanation of symbols]

Reference Signs List 10 pump unit, 12 electric motor, 14 pump (radial piston pump), 16 hydraulic block (pump casing), 18 screw, 20 pump shaft, 22 eccentric ring, 24 needle bearing, 2
6 running sleeve, 27 piston, 28, 30
Ball bearings, 32 motor shafts, 34 inner rings, 36 motor bearings, 38 motor casings, 40 cut-down parts, 42 joints, 44 joint shafts, 46 intermediate sections, 48 end sections, 50, 52

Claims (9)

[Claims] 1. A pump unit for a slip control type vehicle brake device, comprising: a motor having a motor shaft; and a pump shaft non-rotatably connected to the motor shaft via a non-switchable joint. A pump driven by an electric motor, and a bearing disposed between the electric motor and the pump, wherein the bearing directly rotatably supports the pump shaft.
The motor shaft (32) is also directly rotatably supported by a bearing (30) arranged between the electric motor (12) and the pump (14), and the joint (42) is connected to the joint shaft (4).
4), the joint shaft being non-rotatable with the motor shaft (32) and the pump shaft (20) due to form engagement at two positions which are axially separated from each other. A pump unit engaged with the shaft unit in a play in the axial direction. 2. The pump unit according to claim 1, wherein the pump (14) is a non-continuous discharge pump (14). 3. The pump (14) comprises a piston pump (1).
The pump unit according to claim 2, which is (4). 4. The coupling shaft (44) has a multi-edge profile (48), which multi-edge profile and the complementary profiles (50, 52) of the motor shaft (32) and / or the pump shaft (20). The pump unit according to claim 1, which is engaged. 5. The coupling shaft (44) has a reduced cross section (46) axially outside the point of engagement (48) with the pump shaft (20) and the motor shaft (32). The described pump unit. 6. The pump unit according to claim 1, wherein the coupling (42) is formed as an elastic coupling (42). 7. A pump casing (14) for a pump (14) as well as a bearing (30) disposed between an electric motor (12) and a pump (14). The pump unit according to claim 1, wherein the pump unit is also fitted in a bearing receiving portion in (16). 8. A bearing (30) arranged between the electric motor (12) and the pump (14) comprises a pump casing (16).
And a pump shaft (20) is press-fitted into a bearing (30) disposed between the electric motor (12) and the pump (14);
The bearing (28) remote from the motor (12) is press-fitted in a bearing receiving portion in the pump casing (16), and the pump shaft (20) is remote from the motor (12). The pump unit according to claim 1, wherein the pump unit is slidingly fitted in the (28) (movable bearing). 9. A pump casing (16) comprising a bearing (30) disposed between the electric motor (12) and the pump (14).
And the pump shaft (20) is slidingly fitted in a bearing (30) arranged between the electric motor (12) and the pump (14). A movable bearing) and a bearing (28) remote from the motor (12) are press-fitted in a bearing receiving portion in the pump casing (16), and the pump shaft (20) is separated from the motor (12). 2. The pump unit according to claim 1, wherein the pump unit is press-fitted (fixed bearing) in a remote bearing (28).