In for instance volume measuring devices, which are used in gas pipes through which the gas is transported under a high pressure, it is important to keep the volume measuring device properly lubricated in order to minimize measuring errors. The mechanical parts of a volume measuring device therefore have to be well lubricated so as to flush dirt out of the bearings and to minimize friction.

It is known during mounting of such mechanical parts in for instance a natural gas pipe to supply a predetermined quantity of lubricant. The problem however is that this supply of lubricant runs out as a result of, among other things, pressure changes in the natural gas pipe. The pressure changes draw the lubricant out of the bearings and therefore the supply, whereafter it is carried away in the gas flow.

A considerable amount of energy is needed to feed lubricant into the high-pressure environment from outside, since the injection has to take place counter to the high pressure. A battery is not usually sufficient to provide this energy, and a fixed electricity line is required. This is in many cases not possible, or the cost hereof is disproportional.

It is an object of the invention to provide a lubricating device for lubricating mechanical parts in a high-pressure environment, wherein lubricant usage is reduced considerably and the effectiveness of the lubrication is

enhanced.

This objective is achieved according to the invention by a lubricating device which comprises a lubricant reservoir and lubricant level control means for varying lubricant level as desired between a first, high level and a second, low level.

The lubricant level can be controlled by the lubricant level control means so that, as desired, the parts for lubricating can either be brought into contact with the lubricant or not. This prevents the mechanical parts being in continual contact with the lubricant. Lubricant usage is thus reduced.

In a preferred embodiment the lubricating device according to the invention comprises splashing means for splashing lubricant upward from the first lubricant level.

When the lubricant level is brought to the first high level, the splashing means will pass through the lubricant and thus splash the lubricant around, whereby the mechanical parts are lubricated. The splashing means preferably comprise a driven splashing vane.

In another preferred embodiment of the lubricating device according to the invention the lubricant level control means comprise an object displaceable into the lubricant.

This object has a certain volume, and because the object is placed in the lubricant it will displace lubricant, whereby the lubricant level will be raised. Such an object can for instance be arranged eccentrically on a shaft extending outside the high-pressure environment, so that the object can be easily rotated from outside in order to place the object as desired in or out of the lubricant. Translation is of course also possible as well as rotation.

In another preferred embodiment the lubricant level control means comprise a displaceable wall part bounding the

lubricant reservoir. The content of the reservoir can thus be varied with the wall part, which is preferably embodied as a piston, as a consequence of which the lubricant level can be adjusted. To be able to realize this with little energy, an equally high pressure prevails on both sides of the piston.

The invention further comprises a device for measuring the volume of a fluid, which device comprises: - a housing with an inlet opening and an outlet opening, - an impeller arranged in the housing on a mounted shaft, and a detector coupled to the shaft for detecting the number of rotations of the impeller, characterized by a lubricating device according to the invention for lubricating at least the mounted shaft.

It is precisely in such a device that it is of great importance that the mounted shaft remains properly lubricated so as to minimize measuring errors resulting from increased friction in the device. It is furthermore important in such a device that it can operate for some considerable time without any maintenance. Because a lubricating device according to the invention is applied, lubricant usage is less than in prior art devices.

In a preferred embodiment of the device according to the invention the lubricant reservoir a first chamber arranged outside the housing and a second chamber arranged in the housing, which chambers are mutually connected by at least one line. It is thus readily possible to check on the outside of the device whether there is still sufficient lubricant available in the reservoir. The reservoir can thus be provided with for instance a sight-glass. The simplifies checking, and refilling of the lubricant reservoir can be carried out without the device according to the invention having to be disassembled.

In a preferred embodiment of the device according to the invention the lubricant level control means are arranged in the first chamber. This also simplifies construction, since for instance an operating shaft for the lubricant level control means does not have to extend wholly into the device, but only into the first chamber.

In such a measuring device a splashing vane of a lubricating device according to the invention can be arranged on the mounted shaft.

These and other features of the invention are further elucidated with reference to the annexed drawings.

Figure 1 shows in perspective view and with partly cut-away parts the volume measuring device according to the invention.

Figure 2 shows a perspective view of a part of the device of figure 1.

Figures 3A and 3B show the device of figure 1 in perspective view and with cut-away parts, wherein the lubricant level is shown in two different positions.

Figure 4 shows a second embodiment of a measuring device according to the invention in perspective view and with partly cut-away parts.

Figures 5A and 5B show the device of figure 4, wherein the liquid level is shown in two different positions.

Figures 6A and 6B show a third embodiment of a volume measuring device according to the invention having mounted thereon an embodiment of a lubricating device according to the invention.

Figure 7 shows the volume measuring device of figure 6 with another embodiment of a lubricating device according to the invention.

Figure 1 shows a first embodiment of a volume measuring device 1 according to the invention. This device 1

has a housing 2 with two flange parts 3,4. Using these flange parts 3,4 the volume measuring device 1 can be arranged in a pipeline under pressure.

An impeller 5 is arranged in housing 2, which impeller 5 is mounted in a bearing housing 6. Protruding from this bearing housing 6 is a shaft 7 which is coupled to impeller 5. This shaft 7 can for instance be coupled to a detector in order to measure the number of rotations of impeller 5.

In figure 2 the measuring device 1 of figure 1 is shown with partly cut-away parts. Impeller 5 is mounted on a shaft 9 which is mounted in a first bearing 10 and a second bearing 11.

Shaft 7 is connected to shaft 9 by means of two bevel gear wheels 12,13. A splashing vane 14 is further arranged on shaft 9.

A body 15 is further arranged rotatably on a shaft 16, which can be rotated by means of operating shaft 19 by means of a toothed wheel 17 and a pinion 18.

In figure 3A the body 15 is rotated by means of operating shaft 19 such that body 15 is wholly immersed in lubricant 20. The liquid level is hereby raised, so that splashing vane 14 passes through the lubricant and thus causes lubricant to splash upward so as to lubricate bearings 10 and 11 and bevel gear wheels 12 and 13.

In figure 3B the operating shaft 19 is rotated such that body 15 is rotated out of the lubricant 20, whereby the lubricant level is lowered and splashing vane 14 no longer comes into contact with the lubricant.

Figure 4 shows a second embodiment 30 of a device according to the invention. This device corresponds for the most part with the device 1 of figures 1-3. Corresponding parts are therefore designated with the same reference

numerals.

A part of lubricating device 31 can be seen on the outside of housing 2.

In figures 5A and 5B this lubricating device 31 is shown in more detail and with cut-away parts. Lubricating device 31 has a first chamber 32, which is connected via a line 33 to the second chamber present in lubricating housing 6. A return line 34 is provided to equalize pressure differences between first chamber 32 and second chamber 6.

Provided in first chamber 32 is a rotatable body 35, the rotation shaft of which protrudes through the wall of first chamber 32. A sight-glass 36 is further provided in chamber 32 to allow monitoring of the lubricant level. In addition, a filling nipple 37 is further provided to enable the lubricant level to be maintained.

In figure 5A the body is rotated such that it is immersed in the lubricant, thereby raising the lubricant level. Figure 5B shows the situation in which the body 35 is rotated out of the lubricant and the lubricant level is brought to a low level, whereby no further lubricant is used in the second chamber.

Figures 6A and 6B show a device 40 for measuring volume. This device 40 has an inlet opening 41 and an outlet opening 42. Along these flows the gas whose volume has to be measured. Device 40 has a housing 43 in which are arranged two rotors 44 and 45. These rotors 44 and 45 are arranged relative to each other and relative to housing 43 such that they completely seal the passage between inlet 41 and outlet 42. Rotors 44 and 45 are mutually coupled by means of synchronization wheels 46 and 47 such that rotors 44 and 45 are rotated exactly 90'relative to each other. It is important to keep these synchronization wheels 46 and 47 well lubricated in order to minimize wear. If there is too much

wear on the synchronization wheels 46,47, there is then the danger of rotors 44 and 45 rotating too much relative to each other, whereby they can become jammed. A splashing vane 49 is arranged on the shaft 48 of rotor 45. This splashing vane 49 rotates as a result of air flowing in via inlet 41. Coupled to housing 43 is a second lubricating chamber which is formed by closing plates 50 and cap 51. On cap 51 is placed a lubricating device 31 which operates identically to the above described embodiment.

Figure 7 shows the volume measuring device 40 of figure 6. A splashing vane 55 is once again arranged on the shaft 48 of rotor 45. This rotates in a second lubricating chamber formed by the outer wall of housing 43 and the cap 56. A lubricating device 57 is placed on cap 56. This lubricating device 57 comprises a cylindrical housing 58 in which a piston 59 is displaceable. Piston 59 can be displaced by means of piston rod 60. Piston 59 forms a displaceable inner wall of a first lubricating chamber 61. This first lubricating chamber 61 is connected to the second lubricating chamber via channel 62. The lubricant level can be adjusted by displacing the piston 59 such that splashing vane 55 does or does not beat through the lubricant. An opening 63 is preferably further provided at the top of piston 59 in order to enable equalization of the pressure on both sides of the piston.

Opening 63 is further provided to maintain the supply level and to prevent all the lubricant being pressed into the first lubricating chamber when the piston is displaced.