WO2013007905A1

WO2013007905A1 - Combustion engine and pump assembly, and vehicle including such an assembly

Info

Publication number: WO2013007905A1
Application number: PCT/FR2012/051322
Authority: WO
Inventors: Yvon Azou; Mickael CAUSSE
Original assignee: Peugeot Citroen Automobiles Sa
Priority date: 2011-07-08
Filing date: 2012-06-13
Publication date: 2013-01-17
Also published as: FR2977640B1; EP2729692A1; FR2977640A1

Abstract

The invention relates to a combustion engine (12) and pump (14) assembly, wherein: the pump includes: a frame (18) defining a fluid compression chamber (20), which is attached to the engine (16); and a pump piston (26) suitable for compressing the fluid in the compression chamber (20), the piston (26) being translatably guided in a pipe (28) formed in the engine (16) and in the frame (18) of the pump, characterized in that the piston (26) includes a housing, in that the pipe (28) has a rectangular cross-section, and in that the piston (26) is rigidly connected to two rollers engaging with two separate walls of the pipe (28), in order to guide the piston housing (26) in the pipe (28). The invention further relates to a vehicle including said assembly (10). The invention enables carbon-dioxide emissions to be reduced.

Description

ASSEMBLY OF A COMBUSTION ENGINE AND A PUMP AND VEHICLE

INCLUDING SUCH A SET

The present invention claims the priority of the French application 1 156195 filed July 8, 2012 whose content (text, drawings and claims) is here incorporated by reference.

[Ooo2] The invention relates to an assembly of a combustion engine and a pump. It relates to a vehicle comprising such an assembly.

[ooo3] The combustion of fossil fuel such as oil or coal in a combustion system, particularly diesel fuel in a diesel engine, can result in the production of significant amounts of pollutants that can be discharged through the exhaust in the combustion process. environment and cause damage.

[ooo4] In particular, the exhaust gases contain carbon dioxide, denoted by its chemical formula C0 ₂ , which is harmful for humans. It is desirable to reduce carbon dioxide emissions.

[ooo5] Such a reduction can be implemented by improving the quality of current vehicle components. However, such an improvement is accompanied by an increase in vehicle costs, making vehicles with a diesel engine less competitive than vehicles with a gasoline engine.

[ooo6] There is therefore a need for a diesel engine to reduce carbon dioxide emissions at a reduced cost.

[0oo7] For this, the invention provides an assembly of a combustion engine and a pump such that the engine comprises a housing, and the pump comprises a frame defining a fluid compression chamber, fixed on the engine. The pump further comprises a piston adapted to compress fluid present in the compression chamber, the piston being guided in translation in a conduit formed in the engine. The duct is of rectangular section and the piston is integral with two rollers cooperating with two separate walls of the conduit for guiding the piston in the conduit.

Alternatively, the assembly comprises a cam, fixed to a motor shaft adapted to drive the piston in translation. [ooo9] Alternatively, the assembly comprises a spring formed between the frame and the end of the piston opposite the frame, the spring pushing the end of the piston opposite the frame towards the cam.

Alternatively, a cage is attached to the end of the piston opposite to the frame.

[Ooi i] Alternatively, the cage has orifices for the circulation of oil. Alternatively, the cage is provided with a motion transmission interface, the interface being in contact with the cam.

[Ooi 3] Alternatively, the axes of rotation of the rollers are parallel.

Alternatively, the cam is rotated by one of the camshaft and the crankshaft, by means of a belt where appropriate. [0015] In a variant, the engine is a diesel engine.

It is also proposed a motor vehicle comprising an assembly as previously described, the pump being a fuel compression pump arranged on a fuel intake circuit of the engine.

[Ooi 7] Other features and advantages of the invention will appear on reading the following detailed description of the embodiments of the invention, given by way of example only and with reference to the drawings which show:

• Figure 1, a schematic sectional view of an engine architecture;

• Figure 2, a top view of the housing with a cylindrical guide;

FIG. 3, a view of an exemplary assembly according to the invention;

FIG. 4, a perspective view of an example of a cage;

• Figure 5, a sectional view of the cage example;

• Figure 6, a top view of the overall example; FIG. 7, a view of an exemplary assembly according to the invention.

The proposed invention is part of the development of a new vehicle engine architecture, including diesel engine. The engine may in particular be an engine having any number of cylinders. In addition, such an engine can be direct attack. Figure 1 provides a schematic sectional view of this architecture. More specifically, Figure 1 shows an assembly 1 0 of a combustion engine 12 and a pump 14. The assembly 1 0 is part of the powertrain of the vehicle. The pump 14 is a so-called high pressure pump. The pump 14 high pressure can compress fluid. In the case of a diesel engine, the fluid is diesel fuel.

The motor 1 2 comprises different members that are not shown in Figure 1. In this representation, the motor 1 2 comprises a casing 1 6. The casing 1 6 serves as a protective envelope to the motor 1 2 members. [0020] The pump 14 comprises a frame 1 8 delimiting a compression chamber 20. The chamber 20 serves to compress the diesel fuel. The frame 1 8 is fixed on the casing 1 6. In the example of Figure 1, the fixing on the casing 1 6 is made by means of screws passing through the passages 22 of screws. These passages 22 are holes for mounting the frame 18 on the housing 1 6. The precision of the assembly can be facilitated by the presence of a shoulder 24 for easy centering of the pump 14 relative to the bore 25 provided in the casing 1 6 to place the frame 18.

Integrate the compression chamber 20 on the motor 1 2 allows to gain mass for the assembly 1 0 of the motor and the pump. This advantage is obtained by comparison with an engine architecture in which the pump is a device outside the engine provided with a chamber and a frame. This configuration has the same advantage over the case where the engine is equipped with a pump attached to the cylinder head and driven by a belt. A reduction in mass at the assembly 1 0 of the motor and the pump leads to an even greater decrease in the mass of the vehicle. The reduction in mass of the whole results in a decrease in the carbon dioxide emission. Integrate the compression chamber 20 on the engine 12 also saves in terms of size compared to an engine architecture in which the pump is a device outside the engine with a chamber and a frame. According to Figure 1, the pump 14 comprises a piston 26 adapted to compress fluid present in the chamber 20 of compression. The piston 26 is guided in translation in a conduit 28 formed in the housing.

The piston 26 of the pump 14 is however not guided in the lower part. It is desirable to provide such a guiding function. For this, several elements are to be taken into consideration: the mechanical stress recoveries, the high frequency of the piston displacements, the maintenance of the contact between the cam 40 presented with reference to FIG. 3 and the roller 58 (also referred to as English "roller") pump 14, the guarantee of durability and robustness of the various elements of the pump, the control of orientation and control of wear.

Elements providing guiding functions are known from US-A-3 139 076, JP-A-2008291764 and JP-A-2173358 but do not provide optimal solutions to the problems mentioned above. It may also be proposed to provide a cylindrical guide of the piston. Such a guide poses particular problems of indexing. The indexing makes it possible to precisely orient the roller 58 of the pump and the cam. Such a cylindrical guide is therefore generally implemented with indexing. Such an implementation of an indexing is proposed in FIG. 2 which represents a view from above of the casing 16 with a cylindrical guide. According to this example, the indexing is carried out by means of a groove 68 made in the motor 16.

In the field of fuel injection, the principle of the present invention is to remove the cylindrical guide of the piston 26 of the injection pump and to make a rectangular guide with two facing rollers which guide the piston 26 through the room. This technique would indeed to ensure the circulation of the lubricating fluid around the piston 26 by avoiding retention of the fluid, to gain space and time and quality of assembly.

It is thus proposed a conduit 28 in the casing 1 6 which is of rectangular section. Rectangular section for which a different length and width can be defined rather than a square is preferred here.

Such a conduit shape 28 is illustrated schematically in Figures 3 and 7. Figures 3 and 7 are views of an example of assembly 10 according to the invention in different orientations.

In addition, the piston 26 is secured to two rollers 32 and 34 (see also Figure 6 described below). Only the roller 32 is visible in Figure 3, the roller 34 facing him being masked. These two rollers 32 and 34 respectively cooperate with two separate walls 36 and 38 of the duct 28. This cooperation makes it possible to guide the piston 26 in the duct 28.

The assembly 10 further comprises a cam 40. The cam 40 is adapted to drive the piston 28 in translation. According to the example of Figure 3, the cam has three lobes 42. The circular arrow 44 indicates the direction of rotation of the cam 40 about the axis 46. Seen in the direction of the direction A shown in Figure 3, the direction of rotation shown by the arrow 44 corresponds to a direction of rotation anticlockwise about the axis 46. The axis 46 may correspond to a shaft of the motor 12, the shaft to which the cam 40 is secured. The cam 40 is rotated by one of the camshaft and the crankshaft, by means of a belt as appropriate. The assembly 10 comprises a spring 60 formed between the frame 18 and the end of the piston 26 opposite the frame 18. The spring 60 pushes the end of the piston 26 opposite the frame 18 to the cam 40. The spring 60 thus has a role of return spring. The combination of a duct 28 of rectangular section and two rollers 32 and 34 allows for a guide of the piston 26. In addition, the rectangular shape with respect to a square shape provides a natural keying since each side can be identified because of differences in length and width. This results in a natural and accurate indexing of the desired position for the pump 14. This indexing facilitates the alignment of the parts for the operator to assembly. This results in a simplified assembly. Therefore, a saving of time can be obtained. This gain concerns both the installation of new engines by an operator and aftermarket repair operations. In addition, the rectangular shape of the guide and the presence of the two rollers allow the recovery of the forces exerted by the lobes 42 of cam 40, at a high frequency, for example of the order of 125 Hz.

Furthermore, the presence of the two rollers 32 and 34 ensures a linear contact between the piston 28 and the two rollers 32 and 34 with respect to the cylindrical guide wherein the contact is only punctual. This results in a reduction of the friction related to the connection rolling / guiding and an increase in durability due to the decrease in the generated wear. In other words, the friction and wear are maintained at the lowest level, while ensuring the recovery of effort. This makes it possible to reduce the mechanical losses by friction and therefore the emission of carbon dioxide by the vehicle.

In addition, the need for lubrication under oil pressure is greatly reduced, which also allows to obtain a reduction of the carbon dioxide emission by the vehicle.

In addition, since the solution is simple, the associated cost is low which reduces the carbon dioxide emission by the vehicle for a reduced cost.

Preferably, the axes of rotation of the rollers 32 and 34 are parallel. This ensures better guidance of the piston 28. According to the example of Figure 3, the guide is provided by a cage 48. The cage 48 secured to 16 is also shown in Figure 4. The cage 48 has a particular volume form. A base can thus be defined for this cage 48. This base 50 is shown schematically in Figure 5. The base 50 corresponds to the intersection between the plane P (plane perpendicular to the walls 36 and 38) and the cage 48. In this figure 5, are represented two rectangles 52 and 54. The rectangle 52 is included in the rectangle 54. This means that the dimensions of the rectangle 52 are strictly smaller than that of the rectangle 54. The base 50 is the surface which is delimited by the two rectangles 52 and 54. The cage 48 corresponds to the volume obtained using the director 56 and the base 50 as previously described.

This improves the realization of the guidance. In addition, with reference to Figure 6, such a configuration facilitates the passage of oil through orifices 59 between the piston 26 which has a cylindrical shape and the cage 48 of rectangular section.

The cage 48 may also be provided with a motion transmission interface 58, the interface 58 being in contact with the cam 40. According to the example of FIG. 3, the interface 58 is a transmitting roller. the movement of the cam 40.

Claims

An assembly (1 0) of a combustion engine (1 2) and a pump (14) such as: - the pump (14) comprises:

a frame (1 8) delimiting a fluid compression chamber (20) fixed to the engine (1 6), and

- a piston (26) of the pump adapted to compress fluid present in the chamber (20) of compression, the piston (26) being guided in translation in a conduit (28) formed in the motor (1 2), and in the frame (1 8) of the pump

characterized in that the piston (26) comprises a cage and that the duct (28) is of rectangular section and that the piston (26) is integral with two rollers (32, 34) cooperating with two separate walls (36, 38). conduit (28) for guiding the piston cage (26) into the conduit (28).

2. The assembly of claim 1, characterized in that it comprises a cam (40), fixed to a motor shaft adapted to drive the piston (26) in translation.

3. The assembly of claim 2, characterized in that it comprises a spring (60) formed between the frame (1 8) and the end of the piston (26) opposite the frame (1 8), the spring ( 60) pushing the end of the piston (26) opposite the frame (18) towards the cam (40).

4. The assembly according to any one of claims 1 to 3, characterized in that a cage (48) is fixed to the end of the piston (26) opposite the frame (1 8).

5. The assembly of claim 4, characterized in that the cage (48) has orifices (59) for the circulation of oil.

6. The assembly according to claims 2 and 4, characterized in that the cage (58) is provided with a motion transmission interface (58), the interface (58) being in contact with the cam (40). .

7. The assembly according to any one of claims 1 to 6, characterized in that the axes of rotation of the rollers (32, 34) are parallel.

8. The assembly according to any one of the preceding claims taken in combination with claim 2, characterized in that the cam (40) is rotated by one of the camshaft and the crankshaft, by means of a belt where appropriate.

9. The assembly according to any one of claims 1 to 8 characterized in that the engine (12) is a diesel engine.

10. A motor vehicle comprising an assembly according to any one of claims 1 to 9, the pump (14) being a fuel compression pump arranged on a fuel intake circuit of the engine (12).