WO2019126853A1

WO2019126853A1 - Fuel pump comprising a fuel flow control electrovalve

Info

Publication number: WO2019126853A1
Application number: PCT/BR2018/050479
Authority: WO
Inventors: Felipe Nista FECIANO; Anderson Cortez GONSALVES; Bruno Viana Contin HUNGER; Silvio Batista PEREIRA
Original assignee: Robert Bosch Limitada
Priority date: 2017-12-27
Filing date: 2018-12-21
Publication date: 2019-07-04
Also published as: BR102017028327A2

Abstract

The present invention refers to a fuel injection pump, preferably for internal combustion engines, provided with a pumping unit and a fuel flow control electrovalve assembly, in particular comprising a movable valve sealing actuator and a valve end stroke stop, and preferably a fuel flow control electrovalve assembly with a valve end stroke stop provided with a seat and a thread, so as to prevent the breakage and wearing of its contact portion due to the impact of the valve sealing actuator, in addition to allowing reliability and easy assembly.

Description

FUEL PUMP COMPRISING A FUEL FLOW CONTROL ELECTROVALVE

Field of the Invention

[0001 ] The present invention refers to a fuel injection pump, preferably for internal combustion engines, provided with a pumping unit and a fuel flow control electrovalve assembly, in particular comprising a movable valve sealing actuator and a valve end stroke stop.

[0002] Preferably, the present invention refers to a fuel flow control electrovalve assembly with a valve end stroke stop provided with a configuration so as to prevent the breakage and wearing of its contact portion, due to the impact of the valve sealing actuator, in addition to allowing reliability and easy assembly.

Basis of the Invention

[0003] As is well known to those skilled in the art, fuel injection pumps, in particular fuel injection pumps for internal combustion engines, are intended to transfer/ pump the fuel stored in a tank to the engine power system.

[0004] In this manner, a fuel pump comprises at least one fuel inlet, at least one fuel outlet and at least one fluidic circuit for circulation of the fuel. It is common for the said fluidic circuit to comprise at least one electrovalve dedicated to the control of the fuel flow.

[0005] It is of utmost importance to mention that the basic construction and functional principles of fuel pumps are widely known to those skilled in the art, and are extensively described in specific technical literatures.

[0006] In any case, and by way of contextualization, Figure 1 illustrates a trivial embodiment of a fuel pump belonging to the current state of the art. Generally, said fuel pump comprises a main body A, and a housing structure B for a solenoid D1 of the movable valve sealing actuator D2 of the electrovalve.

[0007] As known to those skilled in the art, as can be seen in Figures 1 and 2, said fuel flow control electrovalve comprises an end stroke stop C of the valve sealing actuator D2, arranged in a stop chamber in the body of the fuel pump A in which, in particular, the displacement stroke of the valve sealing actuator through the valve opening is defined by the valve end stroke stop.

[0008] Said valve end stroke stop comprises a contact portion E, in which a peripheral front surface F1 is provided to receive a front portion of the valve sealing actuator D2 at the time of its opening displacement, which is promoted by the elastic tension of a valve spring M to seal the fuel passage.

[0009] In this regard, it is also widely known that the closing displacement of the valve sealing actuator, to allow the passage of fuel, is promoted by the interaction of the solenoid, which is selectively driven according to the fuel demand of the internal combustion engine.

[0010] It is also well known to those skilled in the art that, upon de energization of the solenoid, said opening displacement of the valve sealing actuator occurs abruptly due to the elastic tension of said valve spring, generating a large impact of the front portion of the valve sealing actuator on said stop contact portion.

[0011 ] Examples of fuel pumps with such a configuration can be found, for example, in the patent documents DE 102006013703 and DE 102013215909.

[0012] Such an impact generates great mechanical stresses on the entire peripheral surface of the contact portion of the stop, causing its eventual breakage or wearing.

[0013] In this regard, it is important to mention that, typically, the fuel pumps having electrovalve of the state of the art are provided with stops secured by means of an interference fit between an inner surface of the stop chamber and a peripheral radial surface F2 of the stop contact portion, on the electrovalve body.

[0014] Thereby, the peripheral radial surface of the contact portion of the stop receives, through the kinetic energy of said impact, relative axial displacement in relation to said inner surface of the stop chamber, causing premature wearing of the radial surface of the stop, due to an excess of dynamic friction.

[0015] Particularly, the peripheral front surface of the contact portion of the stop receives a direct impact since it is arranged generally perpendicular to the axial displacement axis of the valve sealing actuator.

[0016] In general, fuel pumps with electrovalves may be provided with an end stroke stop which exhibits a core of ductile pearlitic-ferritic material and a superficial peripheral layer hardened by means of traditional heat treatment with high cooling (Carburized Hardened Deep Frozen Tempered) over the entire peripheral surface of the contact portion of the stop to provide greater hardness and strength to the structure of the peripheral front surface and the peripheral radial surface of the stop.

[0017] However, such a solution does not provide appropriate fixing of the end stroke stop in a manner reciprocal to the stop chamber of the valve body, disadvantageously allowing its relative axial displacement, in addition to requiring a high cost of material and energy to perform the hardening of the entire peripheral surface of the stop.

[0018] In this regard, a stop retainer R may be provided, for example, in the form of an plate externally secured by means of at least four long screws P through the valve body, to assist in fixing the stop and, consequently, to decrease or mitigate its relative axial displacement in relation to said inner surface of the stop chamber, causing decrease of the dynamic friction and less wearing of the radial surface of the stop.

[0019] Nevertheless, in a disadvantageous way, such a solution requires a high cost of material for the manufacture of the stop retainer and the long through screws, in addition to high assembly complexity, mainly on a large scale.

[0020] It is important to highlight that, said patent documents DE 102006013703, DE 102013215909 and US 681 1092 disclose fuel pumps comprising valves for flow control, proposing alternative structures for the end stroke element, showing that it may be secured in a manner“threaded”, rather than the externally secured plate. However, such documents do not disclose additional solutions that allow improving the strength of the stop structure to the impacts described above.

[0021 ] In any case, it is noticed that the fuel pumps with electrovalves of the present state of the art, solve part of the problems discussed with resolutions that, disadvantageously, demand great amount of raw material and energy, besides high assembly complexity, generating a high cost for the manufacture of the fuel injection pump, particularly the fuel flow control electrovalve assembly, in addition to failing to provide a definitive and efficient solution for an valve end stroke stop, so as to prevent the breakage and wearing of its contact portion.

[0022] It is based on this scenario that the invention in question arises.

Objects of the Invention

[0023] Therefore, the present invention is basically aimed at solving the problem of wearing and breakage of the valve end stroke stop on the peripheral surface of its contact portion.

[0024] Another object is to provide a suitable fixing of the end stroke stop in a manner reciprocal to the stop chamber of the valve body.

[0025] In addition, one object is to eliminate the dynamic friction arising from the relative axial displacement of the peripheral radial surface of the contact portion of the stop in relation to the inner surface of the stop chamber.

[0026] It is a further object of the present invention to provide a high strength and high hardness valve end stroke seat for receiving a direct impact from the front portion of the valve sealing actuator.

Summary of the Invention

[0027] In order to fully comply with these and other inherent objectives, the present fuel pump comprises a fuel flow control electrovalve, comprising at least one main body 4; at least one electrovalve sealing actuator 5; at least one stop chamber 6 of at least one stop 1 ; wherein the stop 1 comprises a contact portion 11 , a peripheral radial surface 12 and a peripheral front surface 13.

[0028] Furthermore, the fuel pump comprises a thread 22 provided around the peripheral radial surface 12 of the stop 1 ; a valve end stroke seat 23 provided on the peripheral front surface 13 of the contact portion 1 1 of the stop 1 ; and, a hardened tempered superficial front layer is provided in the valve end stroke seat 23.

[0029] According to a preferred embodiment, a thread 61 is provided on the inner surface of the stop chamber 6. Thus, preferably, the stop 1 is threaded in the stop chamber 6 through the interaction between the thread 61 and the thread 22.

[0030] Also according to a preferred embodiment, the valve end stroke seat 23 is only in the region of contact with the electrovalve sealing actuator 5.

[0031 ] Preferably, the hardened tempered superficial front layer of the valve end stroke seat 23 is only in the region of contact with the electrovalve sealing actuator 5.

[0032] In addition, preferably, the hardened tempered superficial front layer of the valve end stroke seat 23 comprises an induction hardening.

Brief Description of the Drawings

[0033] The preferred embodiment of the present invention is described in detail based on the following figures, which:

[0034] Figure 1 schematically shows a conventional fuel pump, which is comprised of a valve stop with through screws and a stop retainer, belonging to the current state of the art.

[0035] Figure 2 shows, in detail, an example of a valve stop with a stop retainer, belonging to the current state of the art.

[0036] Figure 3 shows, in detail, a valve stop threaded in the stop chamber, as in the present invention.

[0037] Figure 4 shows, in detail, a valve stop with thread and induction hardened superficial front layer of the valve end stroke seat, according to a preferred embodiment of the present invention.

[0038] Figure 5 shows, schematically, the fuel pump as defined in the present invention.

Detailed Description of the Invention

[0039] As shown in Figures 3, 4 and 5, the present invention discloses a fuel pump with particular embodiment of a valve end stroke stop.

[0040] Preliminarily, it should be emphasized again that general components and basic functional principles of fuel pumps, such as that illustrated in Figure 5, are well known to those skilled in the art and in addition they are widely described in specialized technical literature.

[0041 ] The present fuel pump comprises a fuel flow control electrovalve assembly and it is essentially composed of a main body 4, a electrovalve sealing actuator 5, a stop chamber 6 arranged on the main body 4 and an end stroke stop 1 , wherein the stop 1 comprises a contact portion 11 , a peripheral radial surface 12 and a peripheral front surface 13.

[0042] The fuel pump further comprises a thread 22 provided around the peripheral radial surface 12 of the stop 1. In addition, a thread 61 is provided on the inner surface of the stop chamber 6.

[0043] Such a construction is provided for a suitable fixing of the stop 1 in a manner reciprocal to the stop chamber 6 of the main body 4, so as to eliminate the dynamic friction between these parts. In this aspect, preferably, the stop 1 is threaded in the stop chamber 6 through the interaction between the thread 61 and the thread 22.

[0044] Furthermore, the stop 1 is provided with a valve end stroke seat 23 arranged on the peripheral front surface 13 of its contact portion 1 1.

[0045] The stop 1 is also provided with a hardened tempered superficial front layer on the valve end stroke seat 23 of the contact portion 1 1 of the stop 1.

[0046] In addition, in the present invention the valve end stroke seat 23 is preferably only in the region of contact with the electrovalve sealing actuator 5 and, preferably, the hardened tempered superficial front layer of the valve end stroke seat 23 only exists in the region of contact with the electrovalve sealing actuator 5.

[0047] Said contact region is defined at least by the area of the end of the sealing actuator 5 which contacts the stop 1 at the time of its opening displacement.

[0048] In a preferred embodiment, with respect to the manufacture of the stop 1 , the superficial front layer of the valve end stroke seat 23 is advantageously hardened by induction.

[0049] It should be mentioned that said induction hardening involves an application of electric power and an induction of stray current on the surface of the end stroke seat 23 to heat it, forming said hardened tempered superficial front layer and, evidently, providing to the stop 1 greater hardness and strength to impact fatigue.

[0050] It is to be highlighted that, in particular, the displacement stroke of the electrovalve sealing actuator 5 is defined by the valve end stroke seat 23, wherein the seat 23 defines a peripheral front surface of the contact portion 1 1 of the stop 1 , which is especially dedicated to receive a direct impact since it is arranged generally perpendicular to the axial displacement axis of the electrovalve sealing actuator 5.

[0051 ] The configuration described above and illustrated in the figures allows the stop 1 to be easily assembled on the stop chamber, rotated and fitted in its ideal position. In this way, an appropriate reciprocal fixing of the stop 1 is obtained in a simple, cost-effective and efficient manner, avoiding the use of additional fixing means.

[0052] There is also no need for hardening treatment over the entire surface of the valve end stroke stop, that is, eliminating the need for hardening treatment of the peripheral radial surface of the stop.

[0053] Not providing hardening treatment in the region of the peripheral radial surface also allows that there is no damage to the material of the stop chamber during the threading movement, that is, at the time of fixing the stop.

[0054] Finally, it is important to emphasize that this configuration allows less industrial resources to be used, since there is no longer any need for the use of excess parts and material for the construction of the fuel injection pump.

[0055] In this aspect, in accordance with the present invention, since the hardened tempered superficial front layer can be provided only in the region of interest of the stop, likewise, less material and excess energy are employed for the construction of the fuel injection pump.

[0056] It is important to highlight that the above description has the sole purpose of describing in an exemplary manner the particular embodiment of the invention in question. It is therefore clear that modifications, variations and constructive combinations of the elements performing the same function in substantially the same manner to achieve the same results, remain within the scope of protection defined by the appended claims.

Claims

1. Fuel pump comprising a fuel flow control electrovalve, comprising:

at least one main body 4;

at least one electrovalve sealing actuator 5;

at least one stop chamber 6 of at least one stop 1 ;

wherein the stop 1 comprises a contact portion 1 1 , a peripheral radial surface 12 and a peripheral front surface 13;

the fuel pump being especially CHARACTERIZED by the fact that:

a thread 22 is provided around the peripheral radial surface 12 of the stop 1 ; a valve end stroke seat 23 is provided on the peripheral front surface 13 of the contact portion 1 1 of the stop 1 ; and

a hardened tempered superficial front layer is provided in the valve end stroke seat 23.

2. Fuel pump, according to claim 1 , CHARACTERIZED by the fact that a thread 61 is provided on the inner surface of the stop chamber 6.

3. Fuel pump, according to claim 1 , CHARACTERIZED by the fact that the stop 1 is threaded in the stop chamber 6 through the interaction between the thread 61 and the thread 22.

4. Fuel pump, according to claim 1 , CHARACTERIZED by the fact that the valve end stroke seat 23 is only in the region of contact with the electrovalve sealing actuator 5.

5. Fuel pump, according to claim 1 , CHARACTERIZED by the fact that the hardened tempered superficial front layer of the valve end stroke seat 23 is only in the region of contact with the electrovalve sealing actuator 5.

6. Fuel pump, according to any one of claims 1 or 5, CHARACTERIZED by the fact that the hardened tempered superficial front layer of the valve end stroke seat 23 comprises an induction hardening.