WO2006097834A2

WO2006097834A2 - Shuttle valve of a lubricant oil pump for internal combustion engines

Info

Publication number: WO2006097834A2
Application number: PCT/IB2006/000598
Authority: WO
Inventors: Giacomo Armenio; Francesco Leoni; Bernardo Celata
Original assignee: Pierburg S.P.A.
Priority date: 2005-03-18
Filing date: 2006-03-17
Publication date: 2006-09-21
Also published as: WO2006097834A3; WO2006097834A8; ITBO20050171A1; DE112006000628T5

Abstract

A shuttle valve (10) of an oil pump (P) for internal combustion engines. The valve (10) is characterised in that for its shutter (16) it is foreseen on one side a first recess (21) hydraulically communicating with a delivery duct (14) and a second recess (18) hydraulically communicating with a space (23) , communicating in turn with a pressure modulator (24) adapted to modulate the oil pressure within. Furthermore, the first recess (21) and the second recess (18) are hydraulically connected together by means of an orifice (22) present in the shutter (16) .

Description

"SHUTTLE VALVE OF A LUBRICANT OIL PUMP FOR INTERNAL COMBUSTION ENGINES"

TECHNICAL FIELD The present invention relates to a shuttle valve of an oil pump for internal combustion engines. BACKGROUND ART

In the most traditional form, bypass valves are calibrated so as to only open at a calibrate level and allow the passage of oil from the delivery duct to the suction duct.

Evidently, said valves only allow to regulate the amount of oil conveyed to the internal combustion engine

"in steps". Indeed, the amount of oil conveyed to the engine increases proportionally to the revolutions

(according to the pump displacement) until the pressure reaches the opening level of the bypass valve. Once reached this level, the amount of oil provided to the engine remains practically constant (or increases slightly with the revolutions according to the progressive opening law of the bypass valve) . With the bypass valve being calibrated to the maximum pressure needed by the engine at high revolution speeds, the valve does not allow to regulate the amount of oil provided to the engine at slow revolution speeds.

However, United States Patent US-A-β 488 479 envisages various solutions for improving the possibility of regulating the delivery oil pressure continuously instead of in steps.

In the examples shown in this document, the delivery pressure of the lubricating oil depends on some characteristic engine parameters, such as for example the revolution speed. In an embodiment shown in this document, for example, the valve shutter is directly moved by a solenoid which acts on an anchor integral with the shutter itself. The solenoid is energised/de-energised adjustably by electronic means according to the characteristic parameters of the oil used and the running parameters of the engine measured by appropriate sensors.

Furthermore, the shutter is subjected to the action of a spring which returns it to closed position once the solenoid is de-energised. However, this embodiment presents a drawback in that the solenoid must be able to provide considerable forces to overcome those generated by the oil pressure and the return spring.

DISCLOSURE OF INVENTION It is therefore the object of the present invention to make a shuttle valve for an oil pump for internal combustion engines free from the drawbacks described above . According the present invention, therefore, a shuttle valve of an oil pump for internal combustion engines as shown in the features contained in claim 1, is made.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described with reference to the accompanying figures illustrating a non- limitative embodiment example thereof, in which:

- figure 1 is a sectional view of a shuttle valve according to the present invention; - figure 2 shows a first graph in which the performance of a valve according to the present invention is compared with that of a conventional valve for a first operating ratio of an internal combustion engine; and figure 3 shows a graph which compares the performance of the valve according to the present invention respective to the same valve of the conventional type shown in figure 2 for a second operating ratio of the same internal combustion engine. BEST MODE FOR CARRYING OUT THE INVENTION As it is known, some of the oil distributed by the pump must return to the intake duct in order to regulate the oil delivery to an internal combustion engine.

In figure 1, it is indicated as a whole by 10 a shuttle valve of an oil pump for an internal combustion engine (not shown) . Such valve 10 is the main object of the present invention.

The valve 10 comprises a valve body 11 in which a chamber 12 is made. The chamber 12 hydraulically communicates with a suction duct 13 and a delivery duct 14.

Furthermore, a pump P (not shown) that, in a known way, is bypassed by the valve 10, is arranged between the intake duct 13 and the delivery duct 14. The pump P and the valve 10 form a pumping group 100.

Furthermore, the chamber 12 foresees a first portion 12a, directly communicating with the delivery duct 14, and a second portion 12b (in series with the first portion 12a) having a transversal section larger than that of the first portion 12a and hydraulically communicating with the suction duct 13.

Therefore, due to the difference in diameters between the portions 12a e 12b, a shoulder 15 is created on which a shutter 16 rests in home position, presenting a transversal section essentially equal to that of the second portion 12b of the chamber 12.

In actual fact, the shutter 16 rests on the shoulder 15 by effect of the elastic action exerted thereupon by a spring 17, one whose first end 17a is accommodated in a recess 18 made in the shutter 16, while a second end 17b is contained in a seat 19 made in a union element 20.

As shown again in figure 1, the shutter 16, in addition to the mentioned recess positioned at its first base 16a, foresees a further recess 21 made at a second end 16b facing the delivery duct 14.

The cavities 18 and 21 hydraulically communicate with an orifice 22a and a channel 22b in series. Furthermore, a space 23 (made in the portion 12b of the chamber 12) , partially occupied by the spring 17, is defined between the shutter 16 and the union 20.

As explained more in detail below, the volume of the space 23 will change according to the internal combustion engine ratio (not shown) lubricated by the pumping group 100.

Additionally, the space 23 hydraulically communicates with a pressure modulator 24, which will only be described briefly to avoid making the present description dull.

Indeed, as shown again in figure 1, the pressure modulator 24 comprises a hollow main body 25 within which a magnetic anchor 26 under the bias of a spring 27 is arranged.

One end of the anchor 26 presses on a ball 28 which interrupts the hydraulic communication between a feeding duct 29, ideal continuation of the seat 19, and of two evacuating ducts 30, 31 towards the outlet (not shown) . A solenoid S connected to electronic means 1000, adapted to also process the signals of oil temperature and viscosity, as well as those related to the endothermic engine operation (not shown) , is accommodated in a space 32 of the main body 25. The solenoid S is coaxial to the anchor 26 and controls the axial displacement of such anchor 24 with methods which will be better explained below.

The shutter 16 presents on an external surface an O- ring 33 which prevents the oil leakage from the delivery duct 14 to the space 23 in the very narrow gap defined between the external surface of the shutter 16 itself and the cylindrical surface of the portion 12b of the chamber 12.

In use, the opening/closing of the pressure modulator 24 can be continuously regulated by electronic means 1000 according to the features of the lubricant oil measured by appropriate sensors (not shown) and to the operating parameters of the endothermic engine (also measured using traditional methods) .

If the ball 28 is pressed by the anchor 26 so as to close the feeding duct 29, the oil pressure in the portion 12a is equal to that in the space 23 (because the portion 12a and the space 23 are hydraulically connected by the recess 21, the orifice 22a and the duct 22b) . Therefore, the shutter 16 will not be displaced and will remain abutting against the shoulder 15, as shown in figure 1.

If, instead, due to a signal from the electronic means 1000, the solenoid S present in the pressure modulator 24 activates a displacement of the anchor 26 according to an arrow Fl, the oil present in the space 23 will be discharged through the evacuating ducts 30, 31.

For this reason, the oil present in the portion 12a will tend to flow towards the space 23 through the orifice 22a (and the duct 22b) at which, due to the well- known laws of hydraulics, there will be a localised loss of pressure.

Therefore, the pressure of the oil in the space 23 will be lower than that of the oil in the portion 12a and consequently there will be a displacement of the shutter 16 towards an arrow Vl.

If the shutter 16 will displace enough to uncover at least part of the suction duct 13, a portion of oil will be short-circuited from the delivery duct 14 to the suction duct 13 itself.

Evidently, the amount of oil conveyed back to the suction duct 13 will be proportional to the pressure difference between the portion 12a and the space 23, and to the extension of the uncovered area of the suction duct 13 itself.

In this way, fine pressure regulation of the delivery pressure in the delivery duct 14 can be obtained.

To return to the closed condition shown in figure 1, the solenoid S of the pressure modulator 24, controlled by the electronic means 1000, will release the anchor 26 which will be displaced according to an arrow F2, inducing a similar movement to the shutter 16 along an arrow V2.

Figure 2 shows a first graph in which the performance of a valve according to the present invention is compared with that of a conventional valve at a first operating temperature of an internal combustion engine.

More in detail, the graph in figure 2 on the abscissa shows the angular speed expressed in revolutions per minute (RPM) of the crankshaft of an internal combustion engine (not shown) , while the ordinate shows the hydraulic power (where "hydraulic power" means the product between "pressure" and "flow rate" of the lubricant oil) .

In the case in point, the pumping group to which the valves are applied is designed to supply 1.5 bars of pressure at 700 RPM at an oil temperature of 140⁰C.

The situation shown in figure 2 is that actually calculated when oil is at 14O⁰C.

The curve (al) refers to the request of the internal combustion engine, while curve (bl) shows the trend of a pumping group equipped with a valve according to the invention (continuous pressure control) .

Curve (cl) instead refers to the trend of a pumping group provided by the traditional type valve (step pressure control) .

As may be noted in figure 2, curve (bl) closer approximates curve (al) than curve (cl) .

This advantage is even more evident for the same pumping group in the situation shown in figure 3 (with an oil temperature of 65⁰C), especially at slow RPM when the hydraulic power required in the case of a pumping group provided with a valve according to the invention is less than half that required by a pumping group provided with a traditional valve (compare curves (b2) and (c2) with curve (a2) ) .

The advantages of the present valve are as follows:

- the solenoid does not act directly on the valve shutter; consequently, in the present invention, the pressure modulator solenoid has only the function of a "switch" and, therefore, there is no need for high forces to move the anchor;

- continuous and simple regulation of the lubricant oil pressure for circulating oil exactly at the pressure needed by the engine; and

- reduced energy draw by the pump.

Claims

1. Shuttle valve (10) of an oil pump (P) for internal combustion engines, said valve (10) comprising: - a main body (11) wherein it is placed a chamber (12) hydraulically connected with a suction duct

(13) and with an oil delivery duct (14); in said chamber

(12) being placed a shutter (lβ) subjected to the action of elastic means (17) , the position of said shutter (16) inside said chamber (12) allowing a communication between said delivery duct (14) and said exhaust duct (13) for discharging the oil; and electronic means (1000) for regulating the position of said shutter (16) on a substantially symmetric axis (a) of the aforesaid shutter (16) ; said valve (10) being characterized in that with regard to said shutter (16) it is foreseen, on one side, a recess (21) hydraulically communicating with said delivery duct (14) and, on the other side, a space (23) also hydraulically communicating with means (24) able to adjust the oil pressure within it, said recess (21) and said space (23) being hydraulically connected to each other by means (22) able to carry out a localized loss of hydraulic load, said means (22) being placed in said shutter (16) .

2. Shuttle valve (10) according to claim 1, characterized in that said pressure modulator (24) comprises a hollow main body (25) within which it is placed a magnetic anchor (26) stressed by elastic means (27), said magnetic anchor being contained in a coaxial solenoid.

3. Shuttle valve (10) according to claim 2, characterized in that an end of said anchor (26) compresses an element (28) interrupting the hydraulic communication between an oil feeding line (29) from said space (23) and evacuating means (30, 31) towards an outlet .

4. Shuttle valve (10) according to any of claims 2, 3, characterized in that said electronic means (1000) are electrically connected to said solenoid (S) in order to carry out an axial displacement of said anchor (26) , said electronic means (1000) being able to work out the oil temperature and oil viscosity signals and those signals concerning the operation of the endothermic engine.

5. Shuttle valve (10) according to claim 2, characterized in that said solenoid (S) does not act directly on said shutter (16) .

6. Pumping group (100) provided with a pump and a valve (10) according to any of claims 1-5.