WO2004057184A1

WO2004057184A1 - Fuel high-pressure pump assembly

Info

Publication number: WO2004057184A1
Application number: PCT/DE2003/003409
Authority: WO
Inventors: Adolf Einberger; Hans-Ulrich Leutwein; Wolfgang Buchhauser; Georg Weigl
Original assignee: Siemens Aktiengesellschaft
Priority date: 2002-12-18
Filing date: 2003-10-14
Publication date: 2004-07-08

Abstract

The invention relates to a fuel high-pressure pump assembly comprising a drive unit (1) and a fuel high-pressure pump (4). The drive unit (1) is coupled to the fuel high-pressure pump (4) via a pump shaft (2). A torque-limiting part (3) is placed between the drive unit (1) and the pump shaft (2), and ensures a disengagement of the pump shaft (2) from the drive unit (1) when a predetermined torque is exceeded. This makes it possible to reliably prevent a blocking of the control drive and thus of the complete drive and the drive wheels. The blocking of the control drive can also be prevented by providing a predetermined breaking point (12) on the pump shaft (2).

Description

description

High-pressure fuel pump assembly

The invention relates to a high-pressure fuel pump arrangement with a drive unit and a high-pressure fuel pump, the drive unit being coupled to the high-pressure fuel pump via a pump shaft.

DE 198 48 035 AI discloses a high-pressure fuel pump for generating high-pressure fuel in fuel injection systems of internal combustion engines, in particular in a common rail injection system. Such a high-pressure pump is driven either directly via a clutch from the camshaft or indirectly via a control drive. Mainly traction mechanisms or gearwheels are used as control drives. A fuel high pressure pen arrangement with a control drive is known for example from DE 196 24 240 C2. Relatively small torques are required to drive the high-pressure fuel pump. In particular in the case of the commonly used radial piston pumps, each with pistons offset by 120 degrees to one another, only torques of about 16 numbers result. However, the torque can rise very sharply due to a malfunction of the high pressure fuel pump. If such a malfunction causes the high-pressure fuel pump to jam, the torque can increase so much that the entire drive and the drive wheels lock. This can lead to dangerous vehicle reactions. In addition, a fixed high-pressure fuel pump can cause major damage to the engine.

In order to largely rule out malfunctions of the high-pressure fuel pump, all of the individual parts of the pump are manufactured with very high and cost-intensive quality measures and high manufacturing outlay. Nevertheless, Malfunctions of the high-pressure fuel pump cannot be ruled out with absolute certainty.

The object of the invention is therefore to provide a high-pressure fuel pump arrangement which reliably prevents the complete drive and the drive wheels from blocking due to a malfunction of the pump.

The object is achieved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subordinate claims.

The invention is characterized in that if the pump malfunctions and a specified torque is exceeded, the pump shaft is decoupled from the drive unit. Decoupling is simply ensured by a predetermined breaking point on the pump shaft or an additional torque-limiting component. In the former case, the pump shaft breaks when a specified torque is exceeded, thus ensuring that the drive unit is decoupled from the pump shaft. In the latter case, the additional component, which is arranged between the drive unit and the pump shaft, ensures that a decoupling of the drive unit from the pump shaft is ensured when a predetermined torque is exceeded. In both cases, it is ensured that a malfunction of the high-pressure fuel pump and the associated exceeding of a specified torque does not result in the drive unit and the drive wheels being blocked. This safely prevents dangerous vehicle creations due to the blocking drive wheels and major engine damage.

A preferred embodiment of the invention provides that the torque-limiting component is a torque-actuated clutch. Torque actuated clutches have the advantage that they allow the shift torque to be set precisely. A particularly advantageous embodiment of the invention provides that the torque-operated clutch is a slip clutch or a locking body safety clutch. These torque-actuated clutches limit the torque to be transmitted, and if the permissible torque is exceeded, the torque-limiting component is not destroyed. This makes these couplings suitable for maintenance-free continuous use.

A further preferred embodiment of the invention provides that the torque-limiting component is designed as a form-locking element, which is destroyed when a predetermined torque is exceeded and thereby ensures the decoupling of the pump shaft from the drive unit. A wedge connection or a spring connection or a pin connection is used particularly advantageously as a positive connection. The positive locking elements ensure a safe limitation of the maximum torque to be transmitted and are available as inexpensive standard components.

A further preferred embodiment of the invention provides that a frictional connection is used as the torque-limiting component, the frictional connection being designed in such a way that only a predetermined torque can be transmitted. Is particularly advantageous as a frictional

Connection used a press connection or a clamping element connection or a cone connection. The frictional connections have the advantage that they do not completely interrupt the flow of power when the permissible torque is exceeded, but only limit it to the permissible torque.

Exemplary embodiments of the invention are explained below using the schematic drawings. Show it:

FIG. 1 shows a high-pressure fuel pump arrangement with a schematically illustrated torque-limiting component, FIG. 2 shows a high-pressure fuel pump arrangement in a schematic representation with a control drive and torque-limiting component,

FIG. 3 shows a pump shaft of a high-pressure fuel pump arrangement with predetermined breaking point,

FIG. 4 shows a slip clutch for use as a torque-limiting component of the high-pressure fuel pump arrangement,

FIG. 5 shows a locking body safety coupling for use as a torque-limiting component,

FIG. 6 shows a spring connection as a torque-limiting component,

FIG. 7 shows a wedge connection as a torque-limiting component,

FIG. 8 shows a press connection as a torque-limiting component,

Figure 9 shows a cone connection as a torque connecting component.

Functionally identical elements are provided with the same reference symbols throughout the figures.

FIG. 1 shows a high-pressure fuel pump arrangement with a drive unit 1 and a fuel pump 4 (partial section). The drive unit is preferably the crankshaft or the camshaft. The drive unit 1 is coupled to the high-pressure fuel pump 4 via the pump shaft 2. The connection between the drive unit 1 and the pump shaft 2 can take place via a fixed coupling, for example an Oldham coupling or via a control drive. A torque-limiting component 3 is arranged between the drive unit 1 and the pump shaft 2 and is only shown schematically in FIG. 1. Preferred exemplary embodiments of the torque-limiting component 3 are shown in FIGS. 4 to 9. FIG. 2 shows a high-pressure fuel pump arrangement with a control drive, in which the torque is first transmitted from the crankshaft 6 to the camshaft 8 and from there to the pump shaft 2. The power is transmitted via a belt drive. The belt drive consists of a first driving pulley 7, which is fixedly connected to the crankshaft 6 and a second driven pulley 9, which is fixedly connected to the camshaft. The two disks 7 and 9 are connected to one another via a first belt 10. The camshaft 8 is in turn via a second belt 11 and a third pulley 5, which is fixed to the pump shaft

2 is connected, coupled. A torque-limiting component is located between the third disks 5 and the pump shaft 2

3 arranged. The torque-limiting component 3 ensures that when a predetermined torque is exceeded

Decoupling of the pump shaft 2 from the third pulley 5 is ensured. As a result, even when a predetermined torque is exceeded, the entire drive, including the camshaft 8 and the crankshaft 6, does not come to a standstill and thus blocks the entire drive and the drive wheels.

The transmission of the torque from the drive unit to the pump shaft can of course also be done by a different arrangement of the belt drive. For example, the crankshaft can drive the pump shaft directly via a first belt and the pump shaft can drive the camshaft via a second belt. It is also possible for the crankshaft to drive both the camshaft and the pump shaft via a single belt. Such an arrangement is known for example from DE 196 24 240 C2.

Instead of the belt drive, other traction means drives known to the person skilled in the art, such as, for example, chain drives, can of course also be used. A gear drive is also suitable for transmitting the required torque.

FIG. 3 shows a high-pressure fuel pump 4 with a pump shaft 2. Instead of a torque-limiting component here the pump shaft 2 is designed in such a way that it has a predetermined breaking point 12 which, when a predetermined torque is exceeded, ensures that the pump shaft 2 is mechanically destroyed and thus ensures decoupling of the pump shaft 2 from the drive unit (not shown).

Various preferred torque-limiting components are shown in the following FIGS. 4 to 9, each of which ensure that a specified torque on the pump shaft is not exceeded. The torque-limiting component is preferably arranged between the pump shaft and the drive unit. In the case of a drive unit with a control drive, it is also possible to already arrange the torque-limiting component on the shaft driving the pump shaft.

FIG. 4 and FIG. 5 show two preferred exemplary embodiments of torque-actuated clutches which can be used as a torque-limiting component in the high-pressure fuel pump arrangement. FIG. 4 shows a slip clutch 17. The slip clutch 17 is attached directly to the pump shaft 2. The third pulley 5 to be coupled is located on the grain part 13 of the slip clutch 17 between floating friction linings 14. The pulley 5 is mounted directly on the pump shaft 2 treated with permanent sliding protection. The coil springs 15 are held on bolts in the spring support 16 and press the friction surfaces together with the necessary pretensioning force. The torque is set by prestressing the coil springs 15.

FIG. 5 shows a locking body safety clutch 20. In the locking body safety clutch 20, the locking balls 21 are pressed via a disk 22, by a plate spring 23, into a pan-shaped recess in the third pulley 5 mounted on the scar 24. The scar 24 is designed as a perforated disc in which the balls 21 are guided. If the torque set via a nut 26 is exceeded stepped, so the ball 21 lift out of the wells, and the pulley 5 and the scar 24 rotate against each other and the clutch slips. Blocking of the pulley 5 and thus blocking of the entire drive including the drive wheels when the pump shaft 2 jams is thus reliably avoided. Of course, other torque-actuated clutches known to the person skilled in the art can also be used.

FIG. 6 and FIG. 7 show two preferred exemplary embodiments for form-locking elements which can be used as a torque-limiting component in the high-pressure fuel pump arrangement. FIG. 6 shows a feather key connection which is arranged as a torque-limiting component between the pump shaft and the drive unit. The feather key 30 is inserted as a driver in a feather key groove 31 made in the pump shaft. The feather key 30 always has some play on the top 32 to the pulley 5. The feather key 30 forms a positive connection between the drive unit and the pump shaft. When a specified torque is exceeded, the form fit is the spring element 30 destroyed and thereby decoupling the pump shaft 2 from the pulley 5 ensured. FIG. 7 shows a wedge connection, which is arranged as a torque-limiting component between the drive unit and the pump shaft 2. In contrast to the feather key shown in Figure 6, the wedge 40 carries with its lower and upper surface 41 and 42. When a predetermined torque between the pump shaft 2 and the pulley 5 is exceeded, the form-locking element is destroyed again, i.e. of the wedge 40, whereby a decoupling of the pump shaft 2 from the pulley 5 is ensured.

In addition to the feather key and the wedge connection, other form-locking elements known to those skilled in the art can also be used, which are destroyed when a specified torque is exceeded. to ensure decoupling of the pump shaft from the drive shaft. For example, the use of a pin connection is also possible. Pin connections are particularly inexpensive and easy to manufacture.

FIGS. 8 and 9 each show a frictional connection between the drive unit and the pump shaft 2, which are used as torque-limiting components and ensure that the drive unit is decoupled from the pump shaft when a permissible torque is exceeded.

FIG. 8 shows a press connection in which the pulley 5 is pressed onto the pump shaft 2. The press fit is created by joining parts 2 and 5, which have an oversize before assembly. This creates a uniform pressure P over the joint circumference and thus an adhesive force for the transmission of a torque. The frictional connection is designed in such a way that only a predetermined torque can be transmitted. If the predetermined torque is exceeded, the non-positive connection is released and the pump shaft 2 is decoupled from the pulley 5.

Figure 9 shows a cone connection. The tapered connection is established by axially bracing the pulley 5 with the pump shaft 2. For this purpose, the pump shaft 2 has an outer cone and the pulley 5 has a correspondingly shaped inner cone. The two parts are clamped against each other via a clamping screw 50. The bracing results in a frictional connection, as a result of which a torque can be transmitted from the pulley 5 to the pump shaft 2. If a maximum torque is exceeded, the pulley 5 slips on the pump shaft 2 and thus the pump shaft 2 is decoupled from the drive unit 1. The torque can be adjusted accordingly by pretensioning the tensioning screw 50. In addition to the press connection and the taper connection, other frictional connections known to the person skilled in the art can also be used, which are destroyed when a predetermined torque is exceeded and thus ensure that the pump shaft is decoupled from the drive shaft. For example, the use of a clamping element connection is also possible.

The invention thus relates to a torque-limiting component which is arranged between the drive unit and the pump shaft and which ensures that the pump shaft is decoupled from the drive shaft when a predetermined torque is exceeded. The torque-limiting component can be a torque-actuated clutch, a form-locking element or a frictional connection. In addition, material connections such as adhesive welding or solder connections are also possible. The invention is of course not limited to the torque-limiting components shown in the exemplary embodiment. Rather, all torque-limiting components known to the person skilled in the art can be used. The torque-limiting components can be installed directly on the pump shaft or elsewhere in the drive unit. The drive shaft can drive the pump shaft directly via a fixed coupling or via a timing drive. In addition, it is also possible to ensure that the pump shaft is decoupled from the drive unit when a predetermined torque is exceeded by providing the pump shaft itself with a predetermined breaking point, which leads to the pump shaft breaking when an admissible torque is exceeded.

Claims

Expectations

1. High-pressure fuel pump arrangement with a drive unit (1) and a high-pressure fuel pump (4), the drive unit (1) being coupled to the high-pressure fuel pump (4) via a pump shaft (2), characterized in that between the drive unit (1 ) and the pump shaft (2) a torque-limiting component (3) is arranged, which ensures a decoupling of the pump shaft (2) from the drive unit (1) when a predetermined torque is exceeded.

2. High-pressure fuel pump arrangement with a drive unit (1) and a high-pressure fuel pump (4), the drive unit (1) being coupled to the high-pressure fuel pump (4) via a pump shaft (2), characterized in that the pump shaft (2) has a predetermined breaking point (12) which ensures that when a predetermined torque is exceeded the pump shaft (2) breaks and ensures that the pump shaft (2) is uncoupled from the drive unit (1).

3. Fuel high-pressure pump arrangement according to claim 1, characterized in that the torque-limiting component (3) is a torque-actuated clutch.

4. ^' Fuel high-pressure pump arrangement according to claim 3, characterized in that the moment-actuated clutch is a slip clutch (17) or a locking body safety clutch (20).

5. Fuel high-pressure pump arrangement according to claim 1, characterized in that the torque-limiting component (3) is designed as a form-locking element, which provides a positive connection between the drive unit (1) and the pump shaft (2) and is destroyed when a specified torque is exceeded, thereby decoupling the pump shaft (2) from the drive unit (1 ) guaranteed.

6. Fuel high-pressure pump arrangement according to claim 5, characterized in that the positive connection is a spring connection (60) or a wedge connection (70) or a pin connection.

7. High-pressure fuel pump arrangement according to claim 1, characterized in that a frictional connection between the drive unit (1) and the pump shaft (2) is used as the torque-limiting component (3), the frictional connection being designed such that only a predetermined torque is transmitted can be.

8. Fuel high-pressure pump arrangement according to claim 7, characterized in that the frictional connection is a press connection (80) or a clamping element connection or a cone connection (90).