WO2007032718A1

WO2007032718A1 - Oil dipstick

Info

Publication number: WO2007032718A1
Application number: PCT/SE2006/000964
Authority: WO
Inventors: Tommy Sundqvist
Original assignee: Volvo Lastvagnar Ab
Priority date: 2005-09-13
Filing date: 2006-08-24
Publication date: 2007-03-22
Also published as: SE530715C2; SE0502029L

Abstract

The invention relates to an oil dipstick (1) for reading the oil level (12) in a vehicle. In the vehicle, the oil dipstick (1) is placed in an oil dipstick tube (9) and comprises a steel wire (7) that is attached at one end to a handle (8) and is attached at the other end to a measuring tip (2) . The measuring tip (2) comprises a measurement area (3) comprising most of the extent of the measuring tip (2) in the longitudinal direction and is designed with two triangular spacers (4a, 4b) that prevent the measurement area (3) of the oil dipstick (1) coming into contact with oil on the inside of the dipstick tube (9) . This makes it easier to read the correct measurement value of the amount of oil in the vehicle's oil reservoir (10) . The invention also relates to a vehicle comprising the said oil dipstick (1) and dipstick tube (9) .

Description

TITLE: Oil dipstick

TECHNICAL FIELD:

The present invention relates to an oil dipstick for reading the oil level in a vehicle and a vehicle comprising said oil dipstick. The oil dipstick is located in the vehicle inside an oil dipstick tube, and is designed with two triangular spacers that prevent the measurement area of the oil dipstick from coming into contact with the oil on the inside of the dipstick tube. This makes it easier to read the correct measurement value for the quantity of oil in the vehicle's oil reservoir.

BACKGROUND ART:

The reservoir for engine oil in a heavy vehicle is often located under the motor in the front part of the vehicle. The oil reservoir is often called the oil sump. In certain vehicles, for example busses that have a dry sump, the oil reservoir is located alongside the motor. In order to enable the vehicle to run normally, the oil level should be checked at regular intervals . Even when the oil level in a combustion engine can be monitored electronically, it is advantageous to be able to check the oil level manually. In modern heavy vehicles, the distance between the oil reservoir and the outside of the vehicle, where the measuring is carried out, is relatively large and this has meant that the oil dipstick that is used for reading the level is relatively long, up to two metres in a normal heavy vehicle. The length of the oil dipstick means that reading the oil dipstick is complicated, and that the reliability of the measured value is uncertain. Several measurements can be required in order to determine that a correct measurement value has been obtained.

The most common solution for reading the oil level is to mount an elongated oil dipstick tube between the oil reservoir and the location where the oil dipstick is inserted on the outside of the vehicle. This location can, for example, be at the front of the vehicle next to the radiator, or next to the entrance to the cab. Due to a lack of space, this dipstick tube is bent in several places and has a relatively small diameter. The oil dipstick can consist of a measuring tip that is attached to a steel wire that, in turn, is attached to a handle that is located on the outside of the vehicle. The dipstick tube guides the oil dipstick in such a way that its end, the measuring tip, is directed down to the oil reservoir. In order to take a reading, the oil dipstick is withdrawn from the dipstick tube, and is wiped before a reading is taken of the oil level on a measurement area arranged on the measuring tip. During this operation, oil is unintentionally drawn up into the dipstick tube. When the oil dipstick is inserted into the dipstick tube, some of the oil in the dipstick tube coats the measurement area, so that this is coated by a layer of oil, and accordingly the result of the level measurement is difficult to read and is not completely reliable. The measurement result is thus less reliable, due to oil in the dipstick tube coating the measurement area. Accordingly, it is difficult to read the measurement area through the layer of oil. In addition, it can be difficult to determine whether the oil on the measurement area originates from the dipstick tube or from the oil reservoir.

An additional problem is that, during the measurement, the oil dipstick is withdrawn to be read by the oil dipstick with oil having to pass through a relatively long distance in a relatively narrow passage. Some of the oil on the oil dipstick can coat the inside of the dipstick tube when the oil dipstick is withdrawn, and the value that is then read can thus be incorrect .

GB 2 239 317 describes a dipstick for measuring the level of liquid in a container. In the container there is an opening, against the walls of which liquid can be drawn up when wiping the dipstick. The cross section of the dipstick has therefore been designed with three corners and with concave sides. The opening in the container has a corresponding shape to that of the dipstick, so that the dipstick is guided through the opening in the container without lateral play. The concave cross section of the dipstick means, however, that it is difficult to bend if it is manufactured in a material that is required in order to be able to withstand the chemically-demanding environment in a vehicle, and it is therefore not suitable in vehicle applications where the dipstick must be able to be bent during installation and during insertion and withdrawal of the dipstick in an dipstick tube when the measuring is being carried out.

As the whole dipstick has essentially the same shape in a longitudinal direction, it can suitably be guided in an opening in the container which is relatively short.

In a longer dipstick tube in a heavy vehicle, there are, however, obvious risks with this solution that liquid will run down over the measurement area from the edges of the dipstick.

DISCLOSURE OF INVENTION:

The object of the present invention is therefore to achieve an oil dipstick that is simple to use and that provides a reliable measurement value when reading the oil level in an oil reservoir.

The said object is achieved by means of an oil dipstick for reading the oil level in an oil reservoir, which oil dipstick comprises a flexible middle part attached at one end to a handle and attached at the other end to a measuring tip. The said measuring tip has a measurement area comprising most of the extent of the measuring tip in the longitudinal direction, with spacers arranged on both sides of the measurement area - - in the longitudinal direction of the measuring tip, which spacers are designed in such a way that their cross-sectional area is larger than the cross-sectional area of the measurement area of the measuring tip and comprises at least three corners. The measurement area comprises a measurement surface which is a defined surface along the measurement area. The measurement surface is the side on which the reading of the oil level is carried out, and the measurement area is the part of the measuring tip that lies between the spacers .

The spacers are thus designed with a triangular cross section, and with a certain extent in the longitudinal direction. All the corners of the spacers extend beyond the measurement area in the transverse direction, and the difference in the distance between the measurement surface of the measurement area and the outer surface of the spacers is called the offset. More specifically, the offset is the shortest distance in a transverse direction from the measurement surface to the outer surface of the spacers.

The said object is also achieved by a vehicle comprising an oil dipstick according to the description above and an elongated dipstick tube which forms a passage, which said passage forms a guide for the oil dipstick so that its end is directed down into an oil reservoir with the oil dipstick being a suitable size to enable it to slide in the elongated dipstick tube.

The contact surface between the measuring tip and the dipstick tube must thus be as small as possible in order to minimize the risk of oil being transferred from the dipstick tube to the oil dipstick and in particular to the measurement area of the oil dipstick.

In an advantageous embodiment, the spacers are centered in the transverse direction in relation to the measuring tip. By centering is meant in this context that the mid-point of the cross-sectional area of a spacer coincides with the midpoint of the cross- sectional area of the measuring tip. In this embodiment, offset is defined as the shortest distance from the corners of the spacer to the measurement area. This offset is to be of such a size that there is relatively little probability of oil being transferred from the spacers to the measurement area.

In another advantageous embodiment, the measurement area consists of a bevelled flat part along the measurement area, with the measuring tip and the rest of the measurement area having a circular cross section. In this embodiment, the spacers are centered in relation to the measuring tip. The distance between the corners of the spacers and the measurement surface is thus greater than the distance between the corners of the spacers and the measuring tip.

When the measurement area has a rectangular or square cross section, the measurement surface can consist of at least one of the long sides of the measurement area. When the measurement area has a circular cross section, it is also possible for the measurement surface to be defined as a part of the measurement area in the longitudinal direction. The spacers are also centered in relation to the measuring tip in this embodiment .

In another advantageous embodiment, the measuring tip has a square or rectangular cross section with the measurement surface facing one of the sides of each of the spacers. In this embodiment, oil can be transferred from the dipstick tube to the spacers, while the distance to the measurement surface is relatively long, which prevents the oil from being transferred to the measurement surface.

In yet another embodiment, both the measurement area and the spacers have a triangular cross section. The - - measurement surface is located along one of the sides of the triangular measurement area.

An elongated dipstick tube is positioned so that it extends from the outside of the vehicle to the oil reservoir, so that it forms a passage from the outside of the vehicle to the oil reservoir. This passage forms a guide for the oil dipstick, so that the end of the measuring tip is directed down into the oil reservoir. The elongated dipstick tube has an essentially circular cross section. The spacers are dimensioned in the transverse direction in such a way that all three corners extend beyond the measurement area of the measuring tip in the transverse direction, while at the same time the three corners of the spacers are slightly within the internal dimensions of the dipstick tube. The diameter of a circle enclosing the three corners of the spacers is thus less than the internal diameter of the dipstick tube. This makes possible free passage of the oil dipstick in the dipstick tube, and ensures that the cross-sectional area of the dipstick tube is not large, which is important due to the lack of space in modern heavy vehicles. The offset can, for example, be approximately 2 - 2.5 mm and the measuring stick can, for example, be 64 mm long.

In an advantageous embodiment, the cross-sectional shape of the spacers is an equilateral triangle. Also in this case, the spacers can be centered in relation to the measuring tip.

The spacers are essentially identical in design, as regards both shape and size. In an embodiment, the spacers are positioned in such a way that the corners overlap each other in the longitudinal direction.

The solution according to the invention is described in the characterizing part of claim 1 relating to the oil dipstick, and in claim 14 relating to a vehicle comprising the oil dipstick. The other claims contain advantageous embodiments and further developments of the oil dipstick according to the invention.

BRIEF DESCRIPTION OF DRAWINGS:

The invention will be described in greater detail in the following in which

Figure 1 shows a broken view of an oil dipstick according to the invention,

Figure 2 shows a cross section of a spacer and the measurement area,

Figure 3 shows an oil reservoir with an oil dipstick according to the invention arranged in an elongated oil dipstick tube.

MODES FOR CARRYING OUT THE INVENTION:

The embodiments of the invention and further developments described in the following are only to be regarded as examples, and are in no way to limit the scope of the protection provided by the patent. In the embodiments described here, the same reference numerals in the different figures refer to the same type of component .

Figure 1 shows a broken view of an oil dipstick 1 that comprises a flexible middle part in the form of a steel wire 7 that is attached at one end to a handle 8 and is attached at the other end to a measuring tip 2. The middle part can alternatively be manufactured of plastic or some other flexible material . The measuring tip 2 comprises a measurement area 3 comprising most of the extent of the measuring tip 2 in the longitudinal direction. Spacers 4a, 4b are arranged on both sides of the measurement area 3 in the longitudinal direction of the measuring tip 2, which spacers each have three corners 5a, 5b, 5c (see Figure 2) that extend beyond the cross-sectional area of the measurement area 3. The extent of the spacers 4a, 4b in the longitudinal - - direction constitutes at least a small part of the extent of the measuring tip 2 in the longitudinal direction. The measurement area 3 comprises a measurement surface 13 which is a defined surface along the measurement area 3. The measurement surface 13 is the side on which the reading of the oil level is carried out and the measurement area 3 is the part of the measuring tip 2 that is between the spacers 4a, 4b.

Figure 2 shows a cross section of a spacer 4a, 4b, the measurement area 3 and the measurement surface 13. The cross-sectional area of the spacer 4a, 4b is larger than the cross-sectional area of the measurement area 3. The measurement surface 13 and the outer surface of the measurement area 3 lie within the outer surface of the spacers in the transverse direction. The shortest distance from the measurement surface 13 to the outer surface of the spacers 4a, 4b is called the offset 14. It is thus advantageous if the whole of the outer surface of the measurement area 3 lies within the outer surface of the spacers. In this case, the offset is greater than or equal to zero.

In an embodiment, the measuring tip 2 is preferably centered in relation to the spacers 4a, 4b. In this application, the offset 6a, 6b, 6c is defined as the distance between the corners 5a, 5b, 5c of the spacer and the measurement area 3. By offset is meant, in this context, the shortest distance between a corner 5a, 5b, 5c and the measurement area 3. The offset 6a, 6b, 6c is of such a size that it is a compromise between being able to prevent oil being transferred from the spacers 4a, 4b to the measurement area 3 and fulfilling the stringent space requirements in a vehicle application.

Figure 3 shows a partially sectioned view of the oil dipstick 1 in its working position in the oil reservoir 10. The oil dipstick 1 comprises a steel wire 7 that is attached at one end to a handle 8, and is attached at - S - the other end to a measuring tip 2 for measuring the oil level 12.

An elongated oil dipstick tube 9 is positioned from the outside of the vehicle (not shown) to the oil reservoir 10 in such a way that it forms a passage 11 from the outside of the vehicle to the oil reservoir 10. This passage 11 forms a guide for the oil dipstick 1, so that the end of the measuring tip 2 is directed down into the oil reservoir 10. This elongated dipstick tube 9 has an essentially circular cross section. Spacers 4a, 4b are of such a size that they can be inserted into the passage 11 in the dipstick tube 9. As mentioned above, the cross-sectional area of the spacers 4a, 4b is larger than the cross-sectional area of the measurement area 3. When the oil dipstick 1 is removed from the dipstick tube 9, for example to wipe the oil dipstick, a small amount of oil can unintentionally be removed from the oil reservoir 10 when oil from the oil reservoir 10 is taken up into the passage 11 that is formed in the dipstick tube 9. After it has been wiped, the oil dipstick 1 is inserted into the dipstick tube 9 and, as a result of the spacers 4a, 4b that are arranged on the measuring tip 2, the oil in the dipstick tube 9 is prevented from being transferred to the measurement area 3 which is thereby not coated by an unwanted layer of oil, and can therefore give a correct measurement value. As a result of the spacers 4a, 4b, the measurement area 3 thus does not come into contact with oil that has been taken up into the passage 11 in the dipstick tube 9.

An additional advantage of the oil dipstick 1 according to the invention is that the oil dipstick 1 with the measured oil level 12 can be easily withdrawn out of the relatively long passage 11 in the dipstick tube 9, without the measured oil being wiped off on the inside of the dipstick tube 9. This enables the correct value to be read off. - -

The spacers 4a, 4b constitute a small part of the extent of the oil dipstick 1 in the longitudinal direction, with the greater part consisting of the measurement area 3. The measuring tip 2 has preferably two spacers 4a, 4b, but, for longer measuring tips, there can also be three spacers. In an embodiment, these can be positioned equidistant from each other on the measuring tip.

In an embodiment that is relatively simple to manufacture, the measurement area is not specially optimized in relation to the edges or corners of the spacers . This embodiment has relatively low manufacturing costs. Also in this embodiment, the cross-sectional area of the spacers is larger than the cross-sectional area of the measurement area. In addition, the outer surface of the measurement area lies within the outer surface of the spacers.

The invention is not limited to the spacers being positioned with their corners above each other in the longitudinal direction. It is possible to have the corners of one spacer rotated around the longitudinal axis of the measuring tip so that it does not overlap the corners of the other spacers .

Claims

PATENT CLAIMS

1. An oil dipstick (1) for reading the oil level

(12) in an oil reservoir (10), comprising a flexible middle part (7) that is attached at one end to a handle

(8) and is attached at the other end to a measuring tip

(2), which said measuring tip (2) comprises a measurement area (3) comprising most of the extent of the measuring tip (2) in the longitudinal direction, characterized in that spacers (4a, 4b) are arranged on both sides of the measurement area (3) in the longitudinal direction of the measuring tip (2), which spacers (4a, 4b) are designed in such a way that their cross-sectional area is larger than the cross-sectional area of the measurement area (3) of the measuring tip

(2) and comprises at least three corners (5a, 5b, 5c) .

2. The oil dipstick as claimed in claim 1, characterized in that the outer surface of the measurement area (3) lies within the outer surface of the spacers (4a, 4b) .

3. The oil dipstick as claimed in claim 1 or 2 , characterized in that the measurement area (3) comprises a measurement surface (13), which is a defined surface in the longitudinal direction of the measurement area (3) for reading the oil level.

4. The oil dipstick as claimed in claim 3, characterized in that the offset (14) , in other words the shortest distance between the measurement surface

(13) and the outer surface of the spacers (4a, 4b), is greater than or equal to zero .

5. The oil dipstick as claimed in claims 1 to 4, characterized in that the at least three corners (5a, 5b, 5c) of the spacers (4a, 4b) , are centered in relation to the measuring tip (2) .

6. The oil dipstick as claimed in claims 1 to 5, characterized in that the cross section of the measurement area (3) is square.

7. The oil dipstick as claimed in claims 1 to 5, characterized in that the cross section of the measurement area (3) is rectangular.

8. The oil dipstick as claimed in claims 1 to 5, characterized in that the cross section of the measurement area (3) is triangular.

9. The oil dipstick as claimed in claims 6 to 8, characterized in that the measurement surface (13) of the measurement area (3) consists of one of the long sides of the measurement area.

10. The oil dipstick as claimed in claims 1 to 5, characterized in that the cross section of the measurement area (3) is circular.

11. The oil dipstick as claimed in any one of the preceding claims, characterized in that the spacers

(4a, 4b) are two in number.

12. The oil dipstick as claimed in claims 1 to 10, characterized in that the spacers (4a, 4b) are three in number.

13. The oil dipstick as claimed in claim 12, characterized in that the spacers (4a, 4b) are positioned equidistant from each other on the measuring tip (2) .

14. A vehicle comprising an oil dipstick (1) as claimed in any one of claims 1 to 13.