WO2001013065A1

WO2001013065A1 - Spirit level with adjustable accuracy

Info

Publication number: WO2001013065A1
Application number: PCT/IL2000/000390
Authority: WO
Inventors: Shimon Yahav
Original assignee: Gotit Ltd
Current assignee: Gotit Ltd
Priority date: 1999-08-16
Filing date: 2000-07-04
Publication date: 2001-02-22
Anticipated expiration: 2002-02-16
Also published as: AU5562300A; IL131428A0

Abstract

A spirit level (10) including a bubble vial (18) having a channel (30) formed therein, the channel (30) including at least two arms (30A, 30B) generally extending along a first axis (27) fluidly connected to each other by a third arm which extends between the at least two arms (30A, 30B) along a second axis (17) generally perpendicular to the first axis (27), the channel (30) being partially filled with a liquid (32) forming a bubble (33) therein.

Description

SPIRIT LEVEL WITH ADJUSTABLE ACCURACY

FIELD OF THE INVENTION

The present invention relates generally to spirit levels and particularly to a spirit level with adjustable accuracy BACKGROUND OF THE INVENTION

Spirit levels are well known instruments used for setting horizontal or vertical surfaces The level includes a sealed vial containing an air bubble floating in a liquid The particular surface is considered horizontal or vertical when the air bubble rests between predetermined graduated marks in the vial Spirit levels are available with different accuracies Inexpensive commercial levels typically have an accuracy of 1 mm per meter Professional grade spirit levels are highly accurate, and are typically available with an accuracy of 0 03 mm per meter However, such highly accurate levels are quite expensive

Spirit levels generally employ tubular bubble vials or bull's-eye type bubble vials Circular tubes are also known For example, US Patent 1 ,221,738 to Isom describes a level having a circular dial A circular tube is half-filled with a liquid and the top ends of the liquid are used to determine the readings of the level. US Patent 2,904,892 to Tinsley describes a level having a series of intersecting circular vials containing a liquid The vials are held within a bracket which can be adjusted by screws, wherein turning of the screws adjusts the rotation of the vials within the plane of the bracket

Circular tube levels suffer from the drawback that their accuracy, //?ter alia, is dependent upon how accurately the liquid half-fills the circular tube Tubular bubble vials must also be accurately filled with the liquid

SUMMARY OF THE INVENTION The present invention seeks to provide a novel spirit level with adjustable accuracy The spirit level is preferably provided with a bubble vial having a generally U-shaped channel partially filled with a liquid forming a bubble therein The length of the bubble in the channel is adjustable by an adjustment screw which, when suitably turned, tilts the bubble vial and increases the length of the bubble within The larger the bubble the more accurate the measurement, because as the bubble becomes larger it becomes more sensitive to a slight off-horizontal angular tilt of the spirit level about a transverse axis of the level

With sufficiently long arms of the U-shaped channel, the spirit level of the present invention can be easily manufactured to have an accuracy that ranges from 1 mm per meter to 0 01 mm per meter and even better than 0 01 mm per meter The spirit level can easily be made at the price of non-precision commercial levels, and can thus attain and even surpass the accuracy of expensive high precision levels at a fraction of the manufacturing cost.

Other advantages and variations of the spirit level are described hereinbelow There is thus provided in accordance with a preferred embodiment of the present invention a spirit level including a bubble vial having a channel formed therein, the channel including at least two arms generally extending along a first axis fluidly connected to each other by a third arm which extends between the at least two arms along a second axis generally perpendicular to the first axis, the channel being partially filled with a liquid forming a bubble therein

In accordance with a preferred embodiment of the present invention the bubble extends into the at least two arms of the channel Alternatively the liquid extends into the at least two arms of the channel

Further in accordance with a preferred embodiment of the present invention the channel includes a generally U-shaped channel having two generally straight arms

Alternatively the at least two arms are arcuate in shape

Still further in accordance with a preferred embodiment of the present invention the bubble vial is mounted in a body, the body including a level face

In accordance with a preferred embodiment of the present invention the bubble vial is mounted such that the arms of the channel are generally transverse to a longitudinal axis of the body

Further in accordance with a preferred embodiment of the present invention the bubble vial is pivotally attached to the body, and the bubble vial is tillable with respect to the level face of the body about the longitudinal axis, wherein a length of the bubble in the channel changes in accordance with a tilt of the bubble vial

Still further in accordance with a preferred embodiment of the present invention an adjustment screw attaches the bubble vial to the body, the screw being operative to be turned so as to change a tilt of the bubble vial with respect to the level face of the body

Additionally in accordance with a preferred embodiment of the present invention the bubble vial is pivotable about a transverse axis of the body

In accordance with a preferred embodiment of the present invention the bubble vial is transparent Alternatively, the bubble vial may be translucent or opaque Further in accordance with a preferred embodiment of the present invention the bubble vial is formed with graduations

Still further in accordance with a preferred embodiment of the present invention a biasing device is provided against which the bubble vial is biased In accordance with a preferred embodiment of the present invention an additional bubble vial is mounted on the body The additional bubble level may be a bull's eye vial or a tubular bubble vial

Further in accordance with a preferred embodiment of the present invention a digital readout is operatively connected to the bubble vial BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description, taken m conjunction with the drawings in which

Fig 1 is a simplified pictorial illustration of a spirit level constructed and operative in accordance with a preferred embodiment of the present invention, Fig 2 is a simplified sectional illustration of the spirit level of Fig 1, taken along lines II-II in Fig 1 ,

Fig 3 is a simplified exploded illustration of the spirit level of Fig 1, Fig 4 is a simplified top-view illustration of the spirit level of Fig 1, Fig 5 is a simplified pictorial illustration of the spirit level of Fig 1 with a bubble vial tilted, thereby providing the spirits level with a greater accuracy, in accordance with a preferred embodiment of the present invention,

Fig 6 is a simplified sectional illustration of the spirit level shown in the orientation of Fig 5, taken along lines VI- VI in Fig 5,

Fig 7 is a simplified illustration of the bubble vial of the spirit level of Fig 1 generally horizontal,

Fig 8 is a simplified illustration of the bubble vial of the spirit level of Fig 1 tilted down from the horizontal an angle θ,

Fig 9A is a simplified illustration of the spirit level of Fig 1 being used to set a surface, there being a difference in graduations between two ends of a bubble in two arms of a channel in the bubble vial,

Fig 9B is a simplified illustration of the spirit level of Fig 1 tilted to form two discrete bubbles, wherein the same difference in the number of graduations between the two ends of the bubble in Fig, 9A is maintained in the tilted configuration of Fig 9B, Fig 10 is a simplified illustration of a serpentine-like channel in a bubble vial, constructed and operative in accordance with a preferred embodiment of the present invention, Fig 1 1 is a simplified pictorial illustration of the spirit level of Fig 1 with an additional bubble vial, constructed and operative in accordance with a preferred embodiment of the present invention, and

Fig 12 is a simplified pictorial illustration of the spirit level of Fig 1 with a digital readout, constructed and operative in accordance with a preferred embodiment of the present invention

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Reference is now made to Figs 1-4 which illustrate a spirit level 10 constructed and operative in accordance with a preferred embodiment of the present invention Spirit level 10 preferably includes a body 12 made of a sturdy, durable material, such as an aluminum alloy As seen in Fig 2, body 12 may have an I-beam cross section, although other shapes are of course possible and within the scope of the invention Body 12 has a bottom level face 14, preferably machined to a required degree of flatness and smoothness.

A generally rectangular-box-shaped recess 16, generally transverse to a longitudinal axis 17 of body 12, is preferably formed in a central, upper portion of body 12 Recess 16 is configured to receive therein a bubble vial 18, described in detail further hereinbelow Bubble vial 18 is preferably mounted in recess 16 by means of a rod 20 which protrudes from both sides of bubble vial 18 (longitudinally with respect to body 12), rod 20 pivotally being received in grooves 22 formed in recess 16 Rod 20 is preferably held in place by means of a pair of lugs 24 (Figs 3 and 4) which are clamped against rod 20 with screws 26 A soft pad 23, such as a rubber pad, is preferably placed underneath each end of rod 20 By adjusting the tightness of screws 26, one can adjust the rotational orientation of bubble vial 18 about a transverse axis 27 of body 12 (generally perpendicular to longitudinal axis 17), as indicated by a circular arrow 28 in Fig 1 In such a manner, one can calibrate, reset or zero bubble vial 18

As seen best in Fig 4, bubble vial 18 is preferably constructed with a generally U-shaped channel 30 which is partially filled with a liquid 32 Liquid 32 may be introduced into channel 30 through a fill-hole 34 which can be plugged by a plug 36 Channel 30 may have any kind of cross shape (circular, rectangular, triagonal, etc ) This is in contrast with tubular bubble vials of the prior art which must generally have an internal arcuate, somewhat elliptical, shape at ends thereof In addition, channel 30 of bubble vial 18 does not have to be accurately filled with liquid 32, as will be appreciated from the description hereinbelow, this being an important advantage over the prior art A bubble 33 is formed in the liquid 32 and preferably extends into both arms 30A and 3 OB of channel 30 As will be described more in detail hereinbelow, the size of bubble 33 determines the accuracy of the reading of bubble vial 18 The size of bubble 33 means its length and width (or diameter) Therefore, the length and cross-sectional size of channel 30 are factors which determine the size of bubble 33 and the accuracy of bubble vial 18

Bubble vial 18 is preferably transparent or translucent and as such is preferably constructed of a suitable plastic Graduations 38 are preferably formed on bubble vial 18 as seen in the drawings It is noted that graduations 38 are not formed inside the bubble vial as is sometimes done in prior art levels, and thus graduations 38 do not interfere with flow of liquid 32 or bubble 33

As mentioned above, bubble vial 18 is pivotally mounted at one end thereof by means of rod 20 in grooves 22 At the opposite end, bubble vial 18 is attached to the base of recess 16 by means of an adjustment screw 40 which passes through a through hole 41 (Fig. 3) formed in the body of bubble vial 18 and which is threadedly received in a threaded hole 42 (Fig 3) formed in recess 16 By adjusting the tightness of screw 40, one can pivot bubble vial 18 about rod 20, i e , one can adjust the rotational orientation of bubble vial 18 about longitudinal axis 17 of body 12, as indicated by a circular arrow 44 in Fig 1 Preferably the bottom of bubble vial 18 is biased against a biasing device 46, such as a leaf spring mounted to the bottom of recess 16 by a screw 48 Biasing device 46 thus maintains bubble vial 18 at a selected rotational orientation about longitudinal axis 17 as determined by turning screw 40

The manner in which the accuracy of spirit level 10 is adjusted is now described with reference to Figs 1, 2, 5, 6, 7 and 8 In Figs 1, 2 and 7, bubble vial 18 is generally horizontal If spirit level 10 is placed on a level surface, bubble 33 in channel 30 of bubble vial 18 has a length of x in each arm of channel 30 The surface is considered level if the bubble 33 reaches the same graduation 38 in each of the arms of channel 30 If the surface is not level then the bubble 33 in one of the arms of channel 30 will be at a different graduation 38 than in the other arm For example, if the surface to be set is slightly tilted such that the right side of spirit level 10 is higher than the left side (in the sense of the drawings), then the bubble 33 in the right side arm will be at a graduation 38 further towards the end of bubble vial 18 near screw 40 than the bubble 33 in the left side arm It is appreciated that spirit level 10 can be pre-calibrated and markings (not shown) can be provided which can indicate the amount of angular tilt of the surface to be set (Further hereinbelow another embodiment will be described with a digital readout which can also provide the angular tilt of the surface to be set.)

If screw 40 is tightened down, bubble vial 18 will be tilted about rod 20, for example, by an angle #(Fig 8), to the configuration shown in Figs 5 and 6. Because of the tilt of bubble vial 18, bubble 33 now has a length of v in each arm of channel 30, as seen in Fig 8, wherein y ~x As is well known in the art of spirit levels, and as can be appreciated by a simple consideration of trigonometry, the larger the bubble the more accurate the measurement Put in another way, a larger bubble is more sensitive to a slight off-horizontal angular tilt about axis 27 than a smaller bubble As mentioned above, the surface to be set is considered level if the bubble 33 reaches the same graduation 38 in each of the arms of channel 30 If the surface is not level then the bubble 33 in one of the arms of channel 30 will be at a different graduation 38 than in the other arm However, since the bubble 33 is now less sensitive to a slight off-horizontal angular tilt, the bubble 33 in the configuration of Figs 5, 6 and 8 will move less graduations for the same off-horizontal tilt than in the configuration of Figs 1, 2 and 7 Put in another way, a very small off-horizontal tilt of the surface to be set may not be perceived in the configuration of Figs 5, 6 and 8 and the bubble 33 may appear to be at the same graduation 38 in both arms of channel 30 However, the same very small off-horizontal tilt of the surface to be set in the configuration of Figs 1, 2 and 7 will be perceived and the bubble 33 in the right side arm of channel 30 will not be at the exact same graduation 38 as the bubble 33 in the left side arm It follows that the configuration shown in Figs 1, 2 and 7 provides a more accurate spirit level 10 than the configuration shown in Figs 5,6 and 8

Thus by adjusting screw 40 one can adjust the accuracy of spirit level 10 With sufficiently long arms of channel 30, spirit level 10 can be easily manufactured to have an accuracy that ranges from 1 mm per meter to 0 01 mm per meter and even better than 0 01 mm per meter Spirit level 10, which can easily be made at the price of non-precision commercial levels, can thus attain and even surpass the accuracy of expensive high precision levels at a fraction of the manufacturing cost

Since the length of bubble 33 is adjustable, it can now be readily understood that channel 30 does not have to be partially filled with liquid 32 with any high degree of accuracy This saves on manufacturing costs and is a significant advantage over the prior art

An interesting feature of the present invention is that after one has placed the spirit level 10 on a surface to be plumbed or set, one can tilt the spirit level 10 so that the bubble 33 moves to the opposite end of the arms 30A and 30B and the same difference in graduations 38 is maintained even after the spirit level is removed from the surface that was plumbed or set This feature is now explained in detail with reference to Figs. 9A and 9B.

In Fig 9A, spirit level 10 is placed on a surface 60. One end of bubble 33 reaches a graduation 62 in arm 30A and the other end of bubble 33 reaches a graduation 64 in arm 3 OB It is noted in this example that there is a difference of two full graduations between graduations 62 and 64 One can tilt spirit level 10 about axis 17 in the direction of arrow 44, thereby creating two discrete bubbles 33 A and 33B in arms 30A and 30B, respectively, as seen in Fig 9B The bubble 33 A in arm 30A reaches a graduation 66, whereas the bubble 33B in arm 30B reaches a graduation 68 Note that the difference in graduations between graduations 66 and 68 is exactly the same as the difference between graduations 62 and 64 - two full graduations In the configuration of Fig 9B, the bubbles 33A and 33B are "trapped" between the liquid 32 and the ends of each arms 30A and 30B of channel 30. In other words, bubbles 33 A and 33B will remain in their positions shown in Fig 9B as long as the spirit level 10 is not tilted back to re-form a continuous bubble 33 Thus, in this manner, one can plumb or set surface 60, remove spirit level 10 from surface 60, tilt spirit level 10 so as to form the two discrete bubbles 33A and 33B, and read the difference in graduations even when the spirit level is not on surface 60

The skilled artisan will appreciate that bubble vial 18 can be integrated in many other systems that require leveling, such as machine tools or billiard tables, for example The skilled artisan will also appreciate that spirit level 10 can be made with bubble vial 18 at a preset, non-movable angle, thereby providing spirit level 10 with a non-adjustable accuracy.

It will also be appreciated by persons skilled in the art that instead of a single U-shaped channel, bubble vial 18 can be formed in other shapes For example, as seen in Fig 10, a bubble vial 128 can be formed with a serpentine-shape with arcuate arms In general, for any embodiment of the present invention, the bubble vial has a channel 129 formed therein, channel 129 including at least two arms 130 and 131 generally extending along a first axis 132 Arms 130 and 131 are fluidly connected to each other by a third arm 133 which extends between arms 130 and 131 along a second axis 134 generally perpendicular to first axis 132 Channel 129 being partially filled with a liquid 135 forming a bubble 136 therein. The arms may be generally straight as in the embodiment of Fig. 1, or may be arcuate as in the embodiment of Fig 10 It is appreciated by the skilled artisan that spirit level 10 can be suitably fashioned and calibrated not just to set or plumb surfaces at 0° or 90°, but rather at any other angle as well

Reference is now made to Fig 11 which illustrates spirit level 10 with an additional bubble vial, constructed and operative in accordance with a preferred embodiment of the present invention The additional bubble vial may be a bull's eye vial 50 or a tubular bubble vial 52 Bubble vial 18 is generally used to level a surface about axis 27, whereas the additional bubble vial is used to level a surface about axis 17 The additional bubble vial may also be placed on a portion of bubble vial 18 itself, if desired Of course, the additional bubble vial may another bubble vial 18 mounted on the spirit level in a different orientation than the first bubble vial 18

Reference is now made to Fig 12 which illustrates spirit level 10 with a digital readout 54, constructed and operative in accordance with a preferred embodiment of the present invention Digital readout 54 can be operatively connected to bubble vial 18 in a number of ways as is readily appreciated by the skilled artisan For example, liquid 32 can be a conductive fluid and electrical contacts can be provided in bubble vial 18 which provide an electrical signal which is converted to an angular measurement and displayed on digital readout 54 In such an embodiment, bubble vial 18 can be opaque and the angular measurement read at digital readout 54 only It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove Rather the scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art

Claims

C L A I M S

What is claimed is

1 A spirit level (10) comprising a bubble vial (18) having a channel (30) formed therein, said channel (30) comprising at least two arms (30A, 30B) generally extending along a first axis (27) fluidly connected to each other by a third arm which extends between said at least two arms (30 A,

30B) along a second axis (17) generally perpendicular to said first axis (27), said channel (30) being partially filled with a liquid (32) forming a bubble (33) therein

2 The spirit level (10) according to claim 1 wherein said bubble (33) extends into said at least two arms (30A, 30B) of said channel (30)

3 The spirit level (10) according to claim 1 wherein said liquid (32) extends into said at least two arms (30 A, 30B) of said channel (30)

4 The spirit level (10) according to claim 1 wherein said channel (30) comprises a generally U-shaped channel (30) having two generally straight arms (30A, 30B) 5 The spirit level (10) according to claim 1 wherein said at least two arms (130,

131) are arcuate in shape

6 The spirit level (10) according to claim 1 further comprising a body (12) in which said bubble vial (18) is mounted, said body (12) comprising a level face (14)

7 The spirit level (10) according to claim 6 wherein said bubble vial (18) is mounted such that the arms (30A, 30B) of said channel (30) are generally transverse to a longitudinal axis (17) of said body (12)

8 The spirit level (10) according to claim 7 wherein said bubble vial (18) is pivotally attached to said body (12), and wherein said bubble vial (18) is tiltable with respect to said level face (14) of said body (12) about said longitudinal axis (17), wherein a length of said bubble (33) in said channel (30) changes in accordance with a tilt of said bubble vial (18)

9 The spirit level (10) according to claim 8 and further comprising an adjustment screw (40) which attaches said bubble vial (18) to said body (12), said screw (40) being operative to be turned so as to change a tilt of said bubble vial (18) with respect to said level face (14) of said body (12) 10 The spirit level (10) according to claim 8 wherein said bubble vial (18) is additionally pivotable about a transverse axis (27) of said body (12)

1 1 The spirit level (10) according to claim 1 wherein said bubble vial (18) is transparent 12 The spirit level (10) according to claim 1 wherein said bubble vial (18) is translucent

13 The spirit level (10) according to claim 1 wherein said bubble vial (18) is opaque 14 The spirit level (10) according to claim 1 wherein said bubble vial (18) is formed with graduations (38)

15 The spirit level (10) according to claim 1 and further comprising a biasing device (46) against which said bubble vial (18) is biased

16 The spirit level (10) according to claim 6 and further comprising an additional bubble vial (50, 52) mounted on said body (12)

17 The spirit level (10) according to claim 16 wherein said additional bubble (50) level comprises a bull's eye vial (50)

18 The spirit level (10) according to claim 16 wherein said additional bubble (52) level comprises a tubular bubble vial (52) 19 The spirit level (10) according to claim 1 and further comprising a digital readout (54) operatively connected to said bubble vial (18)