GB2232212A - A fitting for an internal combustion engine - Google Patents

Abstract

In an internal combustion engine comprising an overhead cam shaft mounted on the block, an oil line (19) in the block for supplying oil to the cam shaft casing, and a non-return valve (18) and/or pressure restrictor for maintaining a quantity of oil in the casing when the engine is switched off, a fitting (22) provides a by-pass line (23) around the line (19) in case of blockage of the valve (18). The fitting includes a solenoid valve (24), a restrictor (25), and a pressure switch (26) operatively connected to the valve 24. A warning light may be provided. The fitting operates in response to a fall in pressure in the casing. The fitting may alternatively comprise a pressure-sensitive valve. <IMAGE>

Description

A Fitting for an Internal Combustion Engine This invention relates to fittings for internal combustion engines and in particular to engines having a cylinder block, an overhead cam shaft casing mounted on the block, an oil line in the block for supplying oil to the casing and a nonreturn valve and/or pressure restrictor for maintaining a quantity of oil in the casing when the engine is switched off.

This form of engine was mostcommonly found in the Rover SD1 motor cars and over a number of years it has been very common for such cars to experience extensive damage to their cam shafts and valve rockers due to lack of lubrication arising from the non-return valve becoming blocked and hence preventing a proper circulation of oil within the casing. Despite the fact that the resultant repairs can be extremely expensive and the fault occurs frequently enough for AA men to be able to diagnose it almost without lifting the bonnet, no solution has been proposed to date.

Part of the problem is of course that the non-return valve is completely hidden within the engine and is inaccessible for inspection, cleaning or maintenance, other than by separating the cylinder head and cylinder block.

This invention consists in a fitting for an internal combustion engine having a cylinder block, an overhead cam shaft casing mounted on the block, a single oil line for supplying oil to the casing, the fitting comprising a body having an oil passage, a pressure responsive means for producing a control signal and/or for connecting an oil by-pass in parallel with the oil line when the oil pressure in the passage falls below a predetermined level and inlet means for connecting the passage to the oil reservoir within the casing.

At its simplest construction the fitting may also comprise a warning light responsive to the control signal when the pressure in the passage falls below the predetermined level. In this case the motorist will simply have to stop as soon as the warning light comes on in order to avoid damage.

In a preferred embodiment the fitting further includes an oil by-pass line connected in parallel to the oil line, part of the oil by-pass line being constituted by the oil passage and the inlet means.

Conveniently the oil by-pass line may be taken from the tapping in the block for the normal oil pressure detector. For example, a T connector could be put into the tapping so that it could service both the detector and the by-pass line.

In this case the fitting may further comprise a valve for controlling flow through the oil by-pass line and conveniently the valve may be mounted in the body. The valve may be manually operable or it may be automatically operable by the control signal.

In this latter case the fitting may further comprise control means for maintaining the valve open, once it has been open by the control signal, until the engine is switched off.

The inlet means may include a banjo bolt and the body is formed with an opening through which the bolt can pass and into which the oil passage debouches.

Although the invention has been defined above it is to be understood that it includes any inventive combination of the features set out above or in the following description.

The invention may be performed in various ways and specific embodiments will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic view of the unmodified lubrication system of an engine; Figure 2 is a corresponding diagram to Figure 1 with the fitting attached; Figure 3 is a sectional view through the fitting of a part of the engine; Figure 4 is a circuit diagram showing the operation of a warning light; and Figure 5 is a view corresponding to Figure 3 showing an alternative fitting.

Figure 1 shows the basic lubrication system, generally indicated at 10 of the engine. This comprises a sump 11, a suction oil strainer 12, an engine driven oil pump 13, an oil filter 14, an oil relief valve 15, the main oil gallery 16, an oil pressure switch 17 for operating the oil pressure warning light in the vehicle, a restrictor and non-return valve 18 in a line 19 for supplying oil to the overhead cam shaft 20 and rocker shafts 21.

As mentioned previously the purpose of the nonreturn valve and restrictor 18 is to maintain a supply of oil in the cam shaft casing so as to allow for initial lubrication on start up and to adjust the oil pressure or flow to the cam shaft and valve gear.

Referring to Figure 2 a fitting generally indicated at 22 provides a by-pass line 23 around the line 19 and includes a solenoid valve 24, a restrictor 25, and a pressure switch 26.

On start up, in normal operation, the pressure switch will be in its closed position until the oil pressure builds up whereupon it will be opened. As can be seen from Figure 4 in its closed position the switch illuminates a further warning light 27 on the vehicle dashboard. This will go out as soon as a proper pressure is achieved. However, if, due to blockage of the non-return valve 18 insufficient oil is supplied to the cam shaft and rocker shafts the pressure switch 26 remains on or is switched on during running and warning light 27 will be illuminated. A control system 28 will then cause the solenoid valve 24 to open providing a by-pass supply of oil to the cam shaft and rocker shafts via by-pass line 23. The control system 28 is arranged to maintain the valve 24 open until the engine is next switched off.

In order for the fitting 22 to be easily retrofitted to existing engines some care is required with this design. Figure 3 shows a preferred embodiment.

Here it will be seen that the fitting mainly comprises a body 29 having an apertured flange 30 through which is passed a banjo bolt 31 which can be fixed into a tapping 32 in the rocker shaft bore. (In doing so it replaces an existing plug).

The body 29 defines an oil passage 33 which extends from the banjo bolt 31 to the pressure switch 26 and has a branch 34 for connecting to the by-pass line 23. The solenoid valve 24 is mounted on the body 29 and locates in the branch 34.

It will be seen that this simple fitting is capable of readily overcoming the long standing problem with these types of engines. It will be understood that the pressure switch 26 and control system 28 can be effected in many ways, for example, using logic circuitry or a system of relays to ensure that the circuit can efficiently switch an inductive load and prevent self-perpetuating repetitive failure/ restoration cycles which could occur if the pressure switch 26 could switch off the solenoid valve 24 once the by-pass line 23 has restored the pressure.

Figure 5 illustrates an alternative fitting 35 in which the pressure switch 26, valve 24 and control system 28 are replaced by a pressure sensitive valve 36. The valve 36 open in response to a pressure drop across it of a predetermined magnitude, which is set by an adjustment 37 acting on spring 38.

It will be appreciated that the banjo bolt 31 could be connected to the body 29 by means of a flexible pipe if it is desired to have the body 29 in some other location. In that case the flexible pipe would form part of the oil passage 33.

Claims (11)

Claims

1. A fitting for an internal combustion engine having a cylinder block, an overhead cam shaft casing mounted on the block, a single oil line for supplying oil to the casing, the fitting comprising a body having an oil passage, a pressure responsive means for producing a control signal and/or for connecting an oil by-pass in parallel with the oil line when the oil pressure in the passage falls below a predetermined level and inlet means for connecting the passage to the oil reservoir within the casing.

2. A fitting as claimed in Claim 1, further comprising a warning light responsive to the control signal when the pressure in the passage falls below the predetermined level.

3. A fitting as claimed in Claim 1 or Claim 2, further comprising an oil by-pass line, part of the oil by-pass line being constituted by the oil passage and the inlet means.

4. A fitting as claimed in Claim 3, further comprising a valve for controlling flow through the oil by-pass line.

5. A fitting as claimed in Claim 4, wherein valve is manually operable.

6. A fitting as claimed in Claim 4, wherein the valve is operated by the control signal.

7. A fitting as claimed in Claim 6, further comprising control means for maintaining the valve open, once it has been opened by the control signal, until the engine is switched off.

8. A fitting as claimed in Claim 4, wherein in the valve is pressure sensitive and arranged to open when the pressure in the passage falls below the predetermined level.

9. A fitting as claimed in any one of the preceding Claims, wherein the inlet means includes a banjo bolt and the body is formed with an opening through which the bolt can pass and into which the passage debouches.

10. A fitting substantially as hereinbefore described, with reference to the accompanying drawings.

11. A motor vehicle incorporating a fitting as claimed in any one of the preceding Claims.