EP1980729B1 - Cooling nozzle with valve - Google Patents

Abstract

The sprayer has a valve e.g. piston (2), cooperating with a main seat and a return spring (3), where the seat is formed in mass of a sprayer body (1) by a shoulder in an axial through-passage (12). A tubular guide liner (4) in the passage has a downstream liner section (4c) fixed in a downstream retaining section (1c) of the body beyond a radial outlet passage. An upstream section (4b) of the liner terminates in an upstream end (4a) that is axially set back from the seat towards downstream to define an annular fluid passage between the seat and a peripheral space.

Description

The present invention relates to the cooling nozzles of the pistons of an internal combustion engine, for projecting a cooling fluid such as oil against the piston bottom, that is to say against the outer piston face to the explosion chamber, or in a piston gallery.

The piston cooling nozzles usually used are inserts attached to the crankcase and communicating with a coolant supply port. The position of the nozzle is precisely determined to achieve a jet of cooling fluid directed to a specific area of the piston bottom or the piston gallery.

The cooling nozzles generally include a valve, for inhibiting the circulation of cooling fluid until the pressure of the cooling circuit has exceeded a determined threshold value.

Jet structures are generally used, the valve of which is pushed back by a compression spring towards a seat to close off a passage of cooling fluid.

It has been found that some valve cooling nozzles are satisfactory for a limited time, after which time appear wear phenomena that disrupt the sealing of the valve and its proper operation. The correct operating time is shorter as the nominal pressure of the coolant in the cooling lines is high. The wear primarily modifies the opening characteristics of the valve, ie the fluid pressure necessary to trigger the opening: at nine, the valve opens at a correct nominal pressure; after wear, the valve opens at a lower pressure, up to half the correct nominal pressure, therefore below the idle speed of the engine. This results in a disturbance of the general pressure of the fluid in the engine.

It has been observed that wear is inevitable when oscillation and vibration phenomena of the valve occur.

Document is known JP 07 317519 A a jet for engine cooling whose valve is a piston pushed against a seat by a spring and sliding in an axial bore communicating with a radial fluid passage. The phenomena of vibration and wear are reduced. But the piston jets of the document JP 07 317519 A have a relatively large size, and in particular a relatively large length downstream of the nozzle outlet orifices for guiding the piston. Thus, the jet body constitutes a prominence that develops inside the engine cylinder. Too long a length downstream of the nozzle outlets is a risk of collision with the rotating elements of the engine such as the crankshaft or against the weight of the crankshaft, and therefore does not allow use of such a nozzle in some engines.

It was proposed in the document EP 1 273 774 A1 , a cooling nozzle structure that both avoids the vibration of the valve, and reduce the size of the nozzle body inside the engine cylinder. In the first embodiment described in this document, the nozzle body comprises a through axial passage in which are housed a tubular duct guide axial through channel and a valve-shaped piston cooperating with a main seat and a return spring . The nozzle body comprises an upstream section shaped to be connected to a channel for supplying the engine with cooling fluid. The nozzle body comprises an intermediate section having at least one radial outlet passage and a fluid outlet tube. The nozzle body finally comprises a downstream section holding. The valve is mounted to slide axially in an upstream sleeve section towards and away from the main seat, and is pushed axially towards the main seat by the return spring housed itself in the axial channel passing through the tubular jacket of guide. The tubular guide liner comprises an intermediate section which leaves a peripheral space of axial fluid conduction between its outer surface and the inner surface of the axial passage passing through the nozzle body, for the passage of fluid between the main seat and the radial passage of the nozzle. exit.

In this document, the guide sleeve is engaged without play and held in position in an upstream bore of the axial passage through the nozzle body, and is held axially between an upstream ring attached in the nozzle body and a downstream plug also reported in the jet body. A vent is provided in the downstream plug. The main seat is made in the guide jacket.

It turns out that such a nozzle structure is relatively expensive because it requires the manufacture of several parts whose dimensions must be accurate for a satisfactory fit, and it requires an assembly of a relatively large number of parts. In particular, several parts such as the upstream ring, the downstream plug and the upstream portion of the guide liner must be ground, as well as the bores in which these parts engage without play. This results in a high production cost.

The document DE 102 61180 shows a piston cooling nozzle according to the first part of claim 1.

The problem proposed by the present invention is to design a new valve cooling nozzle structure which, at the same time, avoids the phenomena of vibration and wear in operation, has a small overall dimensions in the engine cylinder, and includes a plus low number of parts that are themselves simpler to achieve, avoiding precise machining operations such as grinding.

• le siège principal est formé dans la masse du corps de gicleur par un épaulement du passage axial traversant,
• la chemise tubulaire de guidage comprend un tronçon aval de chemise fixé dans le tronçon aval de maintien du corps de gicleur au-delà du passage radial de sortie,
• le tronçon amont de la chemise tubulaire de guidage se termine par une extrémité amont qui est axialement en retrait du siège principal, vers l'aval, pour définir un passage annulaire de fluide entre le siège principal et l'espace périphérique.

To achieve these objects as well as others, the invention provides a piston cooling nozzle for an internal combustion engine, comprising a through axial passage nozzle body in which are housed a tubular through axial channel guide liner and a valve which cooperates with a main seat and a return spring, the nozzle body having an upstream section shaped to be connected to a cooling fluid supply channel of the engine, an intermediate section provided with at least one radial passage of outlet and a fluid outlet tube, and a downstream holding section, the tubular guide liner being fixed coaxially in the axial through passage and having an upstream section leaving a peripheral space for the axial conduction of fluid between its outer surface and the inner surface of the through axial passage and between the main seat and the radial outlet passage, the valve being mounted to slide axially in the axial channel through the tubular guide liner to and away from the main seat and being pushed axially towards the main seat by the return spring housed in the channel axial through the tubular guide liner; according to the invention:

• the main seat is formed in the mass of the nozzle body by a shoulder of the axial through passage,
• the tubular guide liner comprises a downstream liner section fixed in the downstream section for holding the nozzle body beyond the radial outlet passage,
• the upstream portion of the tubular guide liner terminates in an upstream end which is axially recessed from the main seat, downstream, to define an annular fluid passage between the main seat and the peripheral space.

In that the tubular guide liner is held in the downstream portion for holding the nozzle body, it is no longer necessary to provide an upstream ring and a downstream plug for axially holding the guide liner. Simultaneously, there is no need to provide a rectification of the upstream bore section receiving the upstream ring, nor a rectification of the outer face of the upstream section of the tubular guide liner.

Preferably, the downstream section of the tubular guide liner comprises an annular end flange crimped in a downstream section shoulder of the axial through passage, in the downstream portion of the holding body of the nozzle.

According to this arrangement, the tubular guide liner is effectively fixed in the downstream section of the nozzle body, in a simple and fast manner, by crimping, and its centering may be sufficiently precise to guide the valve perfectly vis-à- screw seat and ensure a good seal when closing the valve.

In practice, the annular end collar may be retained in the downstream shoulder portion of the axial through passage by folding an end skirt of the nozzle body on the downstream end face of the annular end collar. In this way, the nozzle body can be made of simple way by turning operations, including realizing the end skirt.

To improve the centering and maintenance of the upstream section of the liner facing the main seat, for the efficient and precise guidance of the valve, it is possible to provide radial protuberances on the upstream section of the jacket, which coaxially center the upstream section of the jacket in the passage. axial passing through the nozzle body while bearing on the wall of the axial through passage. In this case, the downstream sleeve section is held only by the annular end flange which is crimped in the holding portion of the nozzle body. It is then possible to reduce the overall size of the nozzle body in the engine cylinder, by providing that the downstream section for holding the nozzle body has a length just sufficient for the housing and crimping of the annular end collar of the nozzle. tubular guide liner, beyond the radial outlet passage.

However, the presence of the radial protuberances between the upstream liner section and the wall of the axial through passage can lead to a problem if these radial protrusions are located in the upstream section of the nozzle body, which section is intended to be forcefully introduced into the end bore of a cooling fluid supply channel of the engine block. Indeed, during the engagement in force, the radial stresses exerted on the downstream portion of the nozzle body are transmitted to the tubular guide sleeve by the radial protuberances, and may slightly deform radially the tubular guide sleeve and disturb the free axial sliding of the valve in the tubular guide liner. To avoid this risk, it may be preferable to place the radial protuberances downstream of the downstream portion of the nozzle body, or to choose another means for holding and centering the tubular guide liner: it will then be possible to provide the downstream section of the jacket. tubular guide further comprises a centering section engaged in a corresponding bore of the axial passage through, in the downstream portion of the maintenance of the nozzle body.

In all cases, the tubular guide liner may comprise, in its axial through channel, a shoulder of downstream shrinkage against which is engaged a helical return spring pushing the valve towards the main seat, and which continues with a vent. Thus, the liner is itself the means for holding the return spring, and the vent allows the opening of the valve when the presence of a low fluid pressure.

According to an advantageous embodiment, the tubular guide liner comprises, from its upstream end, a guide bore in which the valve slides with a low clearance and which is limited by a shoulder forming a rear seat against which the valve comes in sealing support when it is pushed back by the fluid under pressure. The presence of the rear seat prevents the passage of fluid to the vent when the valve is pushed at the end of travel by the pressurized fluid.

Preferably, the rear seat is arranged such that, when the valve is resting on the rear seat, it releases a just sufficient section of the annular fluid passage for the desired conduction of the cooling fluid. In this way, it is substantially reduced the pressure from which the fluid pushes the valve at the end against the rear seat, still avoiding the passage of fluid to the vent.

• la figure 1 est une vue éclatée d'un gicleur de refroidissement selon un premier mode de réalisation de la présente invention ;
• la figure 2 est une vue en coupe longitudinale du gicleur de la figure 1, en position d'obturation ;
• la figure 3 est une vue en coupe longitudinale du gicleur de la figure 1, en position d'ouverture ;
• la figure 4 est une vue en coupe longitudinale du gicleur de la figure 1, selon une autre variante à centrage amont de la chemise tubulaire de guidage ;
• les figures 5 et 6 illustrent, en perspective, deux modes de réalisation de la chemise tubulaire de guidage selon la variante de la figure 4 ;
• la figure 7 est une vue éclatée d'un gicleur de refroidissement selon un second mode de réalisation de la présente invention ;
• les figures 8 et 9 illustrent, en coupe longitudinale, le gicleur de la figure 7 respectivement en position d'obturation et en position d'ouverture ; et
• la figure 10 est une vue en coupe longitudinale du gicleur de la figure 7 selon une variante à centrage amont de la chemise tubulaire de guidage.

Other objects, features and advantages of the present invention will become apparent from the following description of particular embodiments, with reference to the accompanying figures, in which:

• the figure 1 is an exploded view of a cooling nozzle according to a first embodiment of the present invention;
• the figure 2 is a longitudinal sectional view of the nozzle of the figure 1 , in the closed position;
• the figure 3 is a longitudinal sectional view of the nozzle of the figure 1 , in the open position;
• the figure 4 is a longitudinal sectional view of the nozzle of the figure 1 , according to another variant with upstream centering of the tubular guide liner;
• the Figures 5 and 6 illustrate, in perspective, two embodiments of the tubular guide liner according to the variant of the figure 4 ;
• the figure 7 is an exploded view of a cooling nozzle according to a second embodiment of the present invention;
• the Figures 8 and 9 illustrate, in longitudinal section, the nozzle of the figure 7 respectively in the closed position and in the open position; and
• the figure 10 is a longitudinal sectional view of the nozzle of the figure 7 according to an upstream centering variant of the tubular guide liner.

In all the embodiments illustrated in the figures, the piston cooling nozzle for an internal combustion engine comprises a nozzle body 1, a valve 2 or 2a, a return spring 3 and a tubular guide liner 4.

Such a cooling nozzle is intended to receive a cooling fluid through an upstream inlet 5 and to distribute this cooling fluid via radial downstream outlets such as the outlets 6 and 7. An axial direction II, and a direction d, are thus defined. fluid flow from the upstream inlet 5 downstream.

The nozzle body 1 as shown comprises an upstream section la with a cylindrical outer surface of revolution ground to be forcefully and sealingly introduced into an end bore of an engine coolant supply channel. (not shown) Alternatively, instead of a section with a ground external surface, it is possible to provide another known means of attachment, for example an attached fixing plate, and a seal provided by an annular seal.

The nozzle body 1 comprises an intermediate section 1b in which a first radial outlet passage 8 and a second radial outlet passage 9 are provided.

The nozzle body 1 further comprises a downstream holding portion 1c whose function is essentially the maintenance of the tubular guide liner 4 as will be explained later.

A first outlet tube 10 is fitted into the first radial outlet passage 8, and forms the first outlet 6 of the nozzle. Likewise, a second outlet tube 11 is fitted into the second radial outlet passage 9, and forms the second outlet 7 of the nozzle.

In the figures, the outlet tubes 10 and 11 are rectilinear. In fact, they may be bent and appropriately shaped to direct the coolant jets to the appropriate areas of the piston or cylinder of the engine to be cooled.

The nozzle body 1 comprises a through axial passage 12 in which are housed the tubular guide liner 4, the valve 2 and the return spring 3. The axial through passage 12 communicates with the outlets 6 and 7 through the radial outlet passages 8 and 9 and the outlet tubes 10 and 11.

Starting from the upstream inlet 5, the axial through passage 12 comprises a cylindrical upstream section 12a, of suitable cross section for the desired flow rate of the cooling fluid, and connected to an intermediate section 12b by a shoulder 12c having a beveled portion forms the main seat 13 of the nozzle.

The intermediate section 12b continues downstream to beyond the radial outlet passages 8 and 9, and its downstream end is connected by a shoulder 12d to a downstream section 12e cylindrical larger diameter, in the downstream section of holding 1c of the nozzle body 1.

At its end opposite the upstream inlet 5, the nozzle body 1 terminates in an end skirt 14 whose function is to retain the tubular guide liner 4, as will be described below.

The tubular guide liner 4 has a through axial channel 15, open at both ends. From the upstream end 4a of the tubular guide liner 4, the axial through channel 15 comprises a guide bore 15a in which the valve 2 or 2a slides with a low clearance and is limited by a shoulder forming a rear seat. 15b. Beyond, downstream, the axial through channel 15 continues axially and comprises a downstream shrinkage shoulder 15c, against which is engaged the return coil spring 3, and which continues with a vent 21.

Now considering the outer surface of the tubular guide liner 4, there is a generally cylindrical upstream portion 4b and a downstream section 4c.

The upstream section 4b has an outside diameter smaller than the inside diameter of the intermediate section 12b of the axial through-passage 12, thus leaving a peripheral space 16 which allows the axial conduction of fluid from the main seat 13 to the radial outlet passages 8 and 9 It is noted that the upstream end 4a of the tubular guide liner 4 is axially recessed from the main seat 13 downstream, to define an annular fluid passage 17 between the main seat 13 and the peripheral space 16.

In all the embodiments, the valve 2 or 2a is mounted to slide axially in the upstream section 4b of the tubular guide liner 4, that is to say in the guide bore 15a of the axial through-channel 15. Thus, the valve 2 or 2a slidably moves towards and away from the main seat 13, and is pushed axially towards the main seat 13 by the return spring 3 housed itself in the axial channel 15 passing through the jacket tubular guide 4.

The downstream section 4c of the tubular guide liner 4 is fixed in the downstream holding portion 1c of the nozzle body 1, beyond the radial outlet passages 8 and 9.

Several embodiments are described, for fixing and maintaining centered the tubular guide liner 4 in the nozzle body 1. In all cases, the downstream section 4c of the tubular guide liner 4 comprises an annular flange of end 18 which is crimped in the downstream section 12e shoulder 12d of the axial through passage 12, in the downstream portion of maintenance 1c of the nozzle body 1.

In practice, the annular end flange 18 bears axially on the shoulder 12d, is guided laterally in the downstream section 12e, and is retained in the downstream section 12e 12d shoulder by folding the end skirt 14 of the nozzle body 1 on the downstream end face of the annular end flange 18. The assembly of the tubular guide liner 4 in the nozzle body 1 can thus be made of easy and fast way, without requiring particularly precise machining. However, it will be possible to crimp an end flange 18 by any other appropriate crimping means.

In the embodiment illustrated on the Figures 1 to 3 , as well as in the embodiment of Figures 7 to 9 , the downstream section 4c of the tubular guide liner 4 further comprises a centering section 19 engaged in a corresponding bore of the through axial passage 12. In practice, the corresponding bore is provided in the intermediate section 12b of the axial through-passage 12, in the downstream holding portion 1c of the nozzle body 1.

In these same embodiments of Figures 1 to 3 and 7 to 9 , the tubular guide liner 4 is thus held only in the downstream holding portion 1c of the nozzle body 1. Its upstream section 4b is left free, without contact with the nozzle body 1, because of the existence of the peripheral space 16 and the annular fluid passage 17. The holding means of the tubular guide liner 4 are however sufficient to ensure proper centering of the valve 2 or 2a vis-à-vis the main seat 13 to ensure a satisfactory sealing in the closed position.

The presence of the peripheral space 16 and the annular fluid passage 17 ensures that the upstream portion 4b of the tubular guide liner 4 will not be subjected to any radial stress capable of deforming it and disturbing the free axial sliding of the valve 2 or 2a in the tubular guide liner 4.

In the variants illustrated on the Figures 4 to 6 and 10 , we find the essential means of the previous embodiments as described on the Figures 1 to 3 and 7 to 9 and these same means are identified by the same reference numerals.

In these variants of Figures 4 to 6 and 10 the difference lies in the holding means of the tubular guide liner 4: in the downstream section 4c, the centering portion 19 has been omitted, and it has been replaced, in the upstream section 4b, by radial protuberances 20 , distributed at the periphery of the external surface of the upstream section 4b, and resting on the wall of the axial through passage 12 in the nozzle body 1. In this case, the tubular guide sleeve 4 is held on the one hand by the crimping of the annular end collar 18, on the other hand by the support of the radial protuberances 20 in the axial through passage 12. It is understood that the transverse protrusions 20 promote the obtaining of a precise centering of the valve 2 or 2a vis-à-vis the main seat 13.

Both variants of radial excrescences 20 illustrated on the Figures 5 and 6 can be used in each of the variants of the figures 4 and 10 .

This different structure of the holding means of the tubular guide liner 4 leads to a possibility of reducing the size of the nozzle in the cylinder of the engine. We see this reduction if we compare, for example, the figures 3 and 4 where the figures 9 and 10 .

On the figures 3 or 9 , the downstream end of the nozzle body 1 is spaced a distance D1 from the downstream edge of the radial outlet passages 8 or 9.

Similarly, on figures 4 or 10 , the downstream end of the nozzle body 1 is located at a distance D2 from the downstream edge of the radial outlet passages 8 or 9.

It is clear that the distance D2 is much smaller than the distance D1, the reduction of distance being made possible, on the figures 4 and 10 by removing the centering section 19.

To benefit from this reduction in distance D2, the downstream holding portion 1c of the nozzle body 1 is given an axial length just sufficient for the housing and crimping of the annular end collar 18, beyond the radial outlet passages. 8 and 9.

In the embodiments of Figures 1 to 4 , the valve 2 is a piston slidably mounted in the tubular guide liner 4. This sliding is seen by considering in succession the Figures 2 and 3 : on the figure 2 , the valve 2 is in the closed position, resting on the main seat 13. On the figure 3 , the valve 2 is in the open position, away from the main seat 13, and resting on the rear seat 15b. In the position of the figure 3 , the support on the rear seat 15b allows the valve 2 to properly seal the axial passage 15, and thus prevent the flow of fluid from the main seat 13 to the vent 21. In the case of a valve 2 in the form of piston, the presence of a rear seat 15b is not essential.

In the embodiment of Figures 7 to 10 , the valve 2a is a ball, also slidably mounted with a low clearance in the tubular guide liner 4. The sliding is visible by considering in succession the Figures 8 and 9 : on the figure 8 , the valve 2a is in the closed position, resting on the main seat 13. On the figure 9 , the valve 2a is in the open position, away from the main seat 13 and resting on the rear seat 15b.

In both embodiments, the rear seat 15b is arranged axially in such a way that, when the valve 2 or 2a bears on the rear seat 15b, it releases a just sufficient section of the annular passage of fluid 17 for fluid conduction. In practice, the passage left between the valve 2 or 2a and the main seat 13 may have substantially the same section as that of the subsequent fluid conduction elements such as the peripheral space 16.

On the other hand, the annular fluid passage 17 and the diameter of the upstream axial passage section 12a will be chosen such that, when the ball-shaped valve 2a is in the closed position ( figure 8 ), the center of the ball-shaped valve 2a is still located downstream of the upstream end 4a of the tubular guide liner 4. This ensures good lateral guidance of the ball-shaped valve 2a in the tubular guide liner 4.

The embodiments which have been described make it possible to provide high flow rates of cooling fluid, with a limited pressure drop, which tends to improve the performance of the nozzle by achieving high jet speeds.

As can be seen in the figures, a nozzle makes it possible to cool several pistons at the same time, in particular in V-shaped engines by providing a plurality of output tubes such as tubes 10 and 11.

The reduced axial size of the nozzle allows its use in the majority of modern engines very compact.

The simplicity and the small number of components make it possible to reduce significantly the cost of manufacture of the nozzle.

The nozzle as described allows to be fixed by fitting the nozzle body by the engine block, without risk of jamming of the valve.

The dimensions of the various components and coolant passages will be selected to meet the flow specifications. The materials can be chosen to meet the specifications.

In practice, the various metal components can be made.

Alternatively, the tubular guide liner 4 can be made by plastic molding.

The presence of the rear seat 15b makes it possible both to protect the return spring 3 by limiting its compression, to immobilize the valve 2 or 2a when the stroke necessary to obtain the maximum requested flow rate is reached, and to limit leaks. by the vent 21 when the coolant is present at high pressure. The particular position of the rear seat 15b, which immobilizes the valve 2 or 2a as soon as the stroke required to obtain the maximum requested flow rate is reached, makes it possible to limit the leaks towards the vent 21 as soon as a relatively low pressure is reached. .

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof within the scope of the claims below.

Claims (10)

1. Piston cooling sprayer for internal combustion engines, including a sprayer body (1) with an axial passage (12) through it in which are accommodated a tubular guide liner (4) with an axial passage (15) through it and a valve (2, 2a) that cooperates with a main seat (13) and a return spring (3), the sprayer body (1) having an upstream section (1a) conformed to be connected to an engine cooling fluid feed passage, an intermediate section (1b) with at least one radial outlet passage (8, 9) and one fluid outlet tube (10, 11), and a downstream retaining section (1c), the tubular guide liner (4) being fixed coaxially in the axial through-passage (12) and having an upstream section (4b) leaving a peripheral space (16) for the axial passage of fluid between its external surface and the internal surface of the axial through-passage (12) and between the main seat (13) and the radial outlet passage (8, 9), the valve (2, 2a) sliding axially in the axial passage (15) through the tubular guide liner (4) toward and away from the main seat (13) and being urged axially toward the main seat (13) by the return spring (3) accommodated in the axial passage (15) through the tubular guide liner (4),
   characterised in that:

   - the main seat (13) is formed in the mass of the sprayer body (1) by a shoulder (12c) in the axial through-passage (12),

   - the tubular guide liner (4) comprises a downstream liner section (4c) fixed in the downstream retaining section (1c) of the sprayer body (1) beyond the radial outlet passage (8, 9),

   - the upstream section (4b) of the tubular guide liner (4) terminates in an upstream end (4a) that is axially set back from the main seat (13), in the downstream direction, to define an annular fluid passage (17)

   between the main seat (13) and the peripheral space (16).
2. Sprayer according to claim 1, characterised in that the downstream section (4c) of the tubular guide liner (4) comprises an annular end flange (18) crimped in a downstream section (12e) with a shoulder (12d) of the axial through-passage (12), in the downstream retaining section (1c) of the sprayer body (1).
3. Sprayer according to claim 2, characterised in that the annular end flange (18) is retained in the downstream section (12e) with a shoulder (12d) of the axial through-passage (12) by bending an end skirt (14) of the sprayer body (1) over the downstream end face of the annular end flange (18).
4. Sprayer according to either of claims 2 or 3, characterised in that the upstream section (4b) of the tubular guide liner (4) is centred coaxially in the axial through-passage (12) of the sprayer body (1) by radial excrescences (20) bearing on the wall of the axial through-passage (12).
5. Sprayer according to claim 4, characterised in that the downstream retaining section (1c) of the sprayer body (1) has a length (D2) just sufficient for accommodating and crimping the annular end flange (18) of the tubular guide liner (4) beyond the radial outlet passage (8, 9).
6. Sprayer according to any one of claims 2 to 4, characterised in that the downstream section (4c) of the tubular guide liner (4) comprises a centring section (19) engaged in a corresponding bore of the axial through-passage (12), in the downstream retaining section (1c) of the sprayer body (1).
7. Sprayer according to any one of claims 1 to 6, characterised in that the tubular guide liner (4) comprises, in its axial through-passage (15), a downstream constricting shoulder (15c) against which is engaged a return coil spring (3) urging the valve (2) toward the main seat (13) and continued by a vent (21).
8. Sprayer according to any one of claims 1 to 7, characterised in that the tubular guide liner (4) comprises, from its upstream end (4a), a guiding bore (15a) in which the valve (2, 2a) slides with a small functional clearance and that is limited by a shoulder forming a rear seat (15b) against which the valve (2, 2a) bears in sealed fashion when it is pushed back by the fluid under pressure.
9. Sprayer according to claim 8, characterised in that the rear seat (15b) is disposed so that, when the valve (2, 2a) is bearing on the rear seat (15b), it frees a just sufficient section of the annular fluid passage (17) for the required flow of the cooling fluid.
10. Sprayer according to any one of claims 1 to 9, characterised in that the valve is a piston (2) or a ball (2a).

Images