Monolithic weighing sensor for scale, and electronic scale

Abstract

To provide a weighing sensor that requires only a small structural space and is manufactured at low cost, and a scale equipped with the weighing sensor.SOLUTION: A monolithic weighing sensor 12 for a scale 10 comprises a ground body 22, and a load introduction unit 24 which monolithically merges into the ground body 22 via a first parallelogram guide 26. The load introduction unit 24 has a load receiving block 36 and a load transmission unit 38. The load receiving block 36 merges monolithically into the load transmission unit 38 by means of a second parallelogram guide 40, and the first parallelogram guide 26 is further hinged on the load transmission unit 38. The load receiving block 36 has a push rod receiving unit for an overload protection unit 16.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a monolithic weighing sensor including a grounding body and a load introduction part that monolithically transfers to the grounding body via a first parallelogram guide. Further, the present invention relates to an electronic scale.

[0002] An electronic scale uses an electronic sensor system to detect the gravitational force exerted on the scale by a load. For example, the sensor system detects the applied force using the principle of electromagnetic force compensation.

[0003] For this purpose, in an electronic scale, a weighing sensor is often used, and a force is introduced into the load introduction part of this weighing sensor. The weighing sensor further transmits the force to the sensor system in order to detect the force.

[0004] Typically, a known weighing sensor has a monolithic structure in which substantial components of the weighing sensor, namely the grounding body, the load introduction part, and the parallelogram guide, are integrally fabricated from a material block.

[0005] Furthermore, it is known to provide an overload protection part in an electronic scale in the area of the weighing sensor to protect the monolithic weighing sensor and the electronic sensor system from damage during an overload.

[0006] The problem of the present invention is to provide a weighing sensor that requires only a small structural space for a scale equipped with the weighing sensor and has a low manufacturing cost, as well as a scale equipped with the weighing sensor.

[0007] According to the present invention, this problem is solved by a weighing sensor as described at the beginning, in which the load introduction part has a load receiving block and a load transmission part. The load receiving block monolithically transfers to the load transmission part via a second parallelogram guide, and a first parallelogram guide is further fastened to this load transmission part. Furthermore, a push rod receiving part for an overload protection part is provided in the load receiving block.

[0008] According to the basic concept of the present invention, a second parallelogram guide is provided in front of the first parallelogram guide in the force direction originating from the load receiving section, and the load receiving block is provided with a push rod receiving section for an overload protection section. As a result, the two parallelogram guides are connected in series, so to speak, and the load receiving block equipped with the push rod receiving section can perform relative motion with respect to the load transmission section. In this case, the overload protection section can come into contact with the push rod receiving section, and this overload protection section prevents the transmission of the overload to the sensor system.

[0009] Advantageously, the first parallelogram guide has two first parallelogram links that hingely connect the load introduction section to the ground. The second parallelogram guide also has two second parallelogram links that hingely connect the load receiving block to the load transmission section, in which case the two first parallelogram links are located in a plane substantially perpendicular to the plane on which the two second parallelogram links are located. By arranging these planes at a right angle, a particularly space-saving weighing sensor can be manufactured. Furthermore, since the load receiving block is optimally guided, it does not tilt when a force is introduced. These planes are defined by the longitudinal central axes of the corresponding parallelogram links, such that the right angle is determined when viewing the weighing sensor from above.

[0010] However, alternatively, the two first parallelogram links and the two second parallelogram links could be located in a single plane.

[0011] In one configuration, the inner wall of the push rod receiving portion of the load receiving block is provided with female threads. The female threads enable simple fixing of the push rod, which may be part of the overload protection portion, in the push rod receiving portion.

[0012] According to one aspect of the present invention, the grounding body has a base extending below the first parallelogram guide and the load introduction section. The base is used as a type of leg for the weighing sensor, and since the casing does not need to receive torque from the grounding body of the weighing sensor, the load on the casing of the upper weighing structure group is reduced.

[0013] According to one embodiment, the second parallelogram guide has two second parallelogram links, with one second parallelogram link extending above and below the load-receiving block. Thus, the load-receiving block is located in the center of the second parallelogram guide, and the load-receiving section can be implemented in a space-saving manner with a relatively small depth.

[0014] Advantageously, the second parallelogram link extending above the load-receiving block has an opening directed toward the load-receiving block. The load-receiving portion, which is connected to the load-receiving block located in the center of the parallelogram guide, can be guided to pass through the opening. The load-receiving portion can be connected to the load-receiving block even though the load-receiving block is located below the upper second parallelogram link.

[0015] Furthermore, the above problems are solved according to the present invention by an electronic scale, particularly an electronic table scale, comprising a casing and a weighing sensor according to the present invention housed in the casing. The grounding body of the weighing sensor is mechanically and firmly connected to the casing, and within the casing are arranged a sensor system for measuring applied force, a stopper fixed to the casing in particular, and a push rod for an overload protection section. The push rod is received by a push rod receiving section in the load receiving block, extends to the stopper, and contacts the stopper when an overload is reached. The electronic scale has a particularly compact structure. Furthermore, only a small number of components are required to form the overload protection section.

[0016] According to one modified embodiment of the present invention, the push rod of the overload protection section is spring-biased in the direction of the load-receiving block. This allows for the definition of a critical overload. The critical overload is precisely the load required for the push rod to abut against the stopper.

[0017] In another embodiment, the overload protection unit includes a leaf spring that spring-biasses the push rod. The leaf spring is inexpensive and can be made of various materials and / or thicknesses, which can be specified according to the desired critical overload.

[0018] In one embodiment, the leaf spring is positioned between the load-receiving block and the stopper in the longitudinal direction of the push rod. In particular, the leaf spring is positioned on the outer surface of the load-transmission section on the stopper side. This allows the leaf spring to easily apply preload to the push rod, and consequently to the load-receiving block.

[0019] Advantageously, the inner wall of the push rod receiving portion in the load-receiving block is provided with female threads. Furthermore, the free end of the push rod is provided with male threads, and the push rod is screwed into the push rod receiving portion of the load-receiving block. By establishing a screw connection, the load-receiving block and the push rod form a stable unit that can be easily assembled.

[0020] According to another aspect of the present invention, the grounding body has a base extending below the first parallelogram guide and load introduction section. In this case, the stopper is positioned on the base of the grounding body on the virtual extension line of the push rod. This allows the good stability provided by the base to be combined with a space-saving overload protection section achieved using the stopper. In this case, the stopper may be integrally formed with the base or may be formed separately from the base.

[0021] According to one modification of the present invention, the overload protection unit is load-controlled and located in the force channel between the load-receiving block and the sensor system. The overload protection unit is configured such that, when the load is below the overload limit, the force applied to the load-receiving block by the load is further transmitted to the sensor system via the load transmission unit. In this case, when the load exceeds the overload limit, the overload protection unit contacts a stopper, and the force is released through the grounding body and / or casing. The overload protection unit, for example, a push rod and a leaf spring, transmits the force until the overload limit is reached. Since the overload protection unit is fixed only to the load introduction unit, the force measured by the sensor system does not affect the overload protection unit unless the load limit is exceeded.

[0022] The present invention will be described below based on the embodiments illustrated in the attached drawings. [Brief explanation of the drawing]

[0023] [Figure 1] The diagram shows a partial perspective view of an electronic scale according to the present invention, which is equipped with a monolithic weighing sensor according to the present invention located inside an outer casing. The scale casing and sensor system are not shown. [Figure 2] Another perspective view of the electronic scale shown in Figure 1, viewed from diagonally below, is also shown. [Figure 3] Figure 1 shows a side view of the electronic scale. [Figure 4] Another side view of the electronic scale shown in Figure 1 is presented. [Figure 5] Figure 3 shows a cross-sectional view of the electronic scale shown in Figure 1, along line VV.

[0024] Figures 1 to 5 illustrate one embodiment of an electronic scale 10, particularly in the form of a table scale. The scale 10 can be used to determine the weight caused by the load applied to the scale 10.

[0025] The electronic scale 10 has a monolithic weighing sensor 12, a sensor system, a casing, a load receiving part 14 and an overload protection part 16, and, for example, a stopper 18 fixed to the casing, and this stopper 18 is arranged, among other things, on the grounding body 22 of the weighing sensor 12.

[0026] Here, the weighing sensor 12, the sensor system, the overload protection part 16 and the stopper 18 are provided inside the casing, and a part of the load receiving part 14 is accessible from the outside of the casing.

[0027] Here, the load receiving part 14 includes, for example, a weighing platform (not shown) positioned outside the casing for receiving the object to be measured and the substance to be measured, and a spacer 20, and the spacer 20 protrudes into the casing and supports the weighing platform.

[0028] Via the weighing platform and the spacer 20, the force exerted by the load is introduced into the inside of the casing.

[0029] Strictly speaking, the force is transmitted from the spacer 20 to the weighing sensor 12, and subsequently, the weighing sensor 12 further transmits the force to the sensor system, and the sensor system determines the value of the force exerted by the load on the load receiving part 14, that is, the mass of the load.

[0030] The sensor system is based on the principle of electromagnetic force compensation and outputs an electrical signal corresponding to the measured value. The functional principle of the sensor system is known from the prior art.

[0031] The weighing sensor 12 is made monolithically, that is, from a single member, and is usually manufactured from a light metal such as aluminum or an aluminum alloy.

[0032] The weighing sensor 12 has a grounding body 22 firmly connected to the casing, and a load introduction part 24 that monolithically transitions to the grounding body 22 via a first parallelogram guide 26.

[0033] The grounding body 22 has a vertically elongated base 28 that is used as a type of leg, and the weighing sensor 12 is placed, for example, at the bottom of the casing using this base.

[0034] The base 28 extends along the first parallelogram guide 26, below the first parallelogram guide 26, and below the load introduction section 24, thereby providing good stability for the weighing sensor 12. Here, "downward" is relative to the weighing sensor 12 installed in the planned operating position, and in this relationship, "downward" means closer to the ground surface, i.e., closer to the bottom of the casing.

[0035] The first parallelogram guide 26 has two first parallelogram links 30, each of which transitions to the ground contact body 22 on one side and to the load introduction section 24 on the other, via two first joints 32. Thus, the load introduction section 24 is hingely connected to the ground contact body 22.

[0036] In addition to the first parallelogram guide 26, the ground contact body 22 and the load introduction section 24 are interconnected via a lever system 34. The lever system 34 is provided to further transmit the force applied to the load introduction section 24 to the sensor system on or inside the ground contact body 22. The lever system 34 is also a one-piece component of the weighing sensor 12.

[0037] The load introduction section 24 includes a load receiving block 36 and a load transmission section 38, which are monolithically connected to each other via a second parallelogram guide 40.

[0038] The second parallelogram guide 40 has two second parallelogram links 42, each of which transitions to a load receiving block 36 on one side and to a load transmission section 38 on the other via two second joints 44.

[0039] In this case, one of the two second parallelogram links 42 extends above the load-receiving block 36, and the other of the two second parallelogram links 42 extends below the load-receiving block 36.

[0040] Here, "upper" and "lower" refer to the weighing sensor 12 installed at the planned operating position, with "lower" meaning closer to the installation surface, i.e., closer to the bottom of the casing, and "upper" meaning further away from the installation surface.

[0041] Furthermore, the second parallelogram link 42 extending above the load-receiving block 36 has an opening 46 that extends through the upper parallelogram link 42 in the direction of the load-receiving block 36.

[0042] The load transmission section 38 is L-shaped when viewed from the side, with the limbs extending upward from the side of the base located below transitioning to the second joint 44 in a single piece. Therefore, this "L" together with the parallelogram link 42 surrounds the load receiving block 36. In other words, the parallelogram link 42 and the load receiving block 36 fill the space enclosed on two sides by the "L", and together with the load transmission section 38 define a rectangular parallelepiped (see Figures 1 and 2).

[0043] As can be seen from Figures 1 and 2, the two first parallelogram links 30 are located in a plane substantially parallel to another plane on which the two second parallelogram links 42 are located. These planes are defined by the longitudinal central axes of the corresponding parallelogram links 30 and 42 so that right angles are determined when the weighing sensor is viewed from above. In Figure 1, the plane of the parallelogram link 30 extends vertically and, in the width direction, with the parallelogram link 30 as the center, extends forward from the grounding body 22 to the load-receiving block 36, i.e., in the longitudinal direction of the parallelogram link 30. The plane of the parallelogram link 42 similarly extends vertically and, in the width direction, with the parallelogram link 42 as the center, extends parallel to the front surface of the load-receiving block 36 shown in Figure 1.

[0044] Furthermore, the load-receiving block 36 has a push rod receiving portion 48 (see Figure 5).

[0045] The inner wall of the push rod receiving portion 48 is provided with female threads 50.

[0046] The overload protection unit 16, mentioned at the beginning of the description of the scale 10, is used to prevent damage to the scale 10 caused by overload. When the force exceeds a predetermined overload, the overload protection unit 16 prevents the force from being fully transmitted to the sensor system.

[0047] For this purpose, the overload protection unit 16 is load-controlled and is located in the force channel between the load receiving block 36 and the sensor system. When the load is below the overload limit, i.e., during normal operation of the scale 10, the force applied to the load receiving block 36 by the load is further transmitted to the sensor system via the load transmission unit 38. Only when the load exceeds the specified overload limit does the overload protection unit 16 contact the stopper 18, and as a result, the force is released through the grounding body 22 and / or the casing.

[0048] For this purpose, the overload protection unit 16 includes a push rod 52 and a leaf spring 54.

[0049] The push rod 52 is received by the push rod receiving portion 48 and extends downward in the vertical direction through the through hole 56 (see Figure 5) in the load transmission portion 38.

[0050] For fixing purposes, the push rod 52 has a male thread 58 at its upper free end, and this male thread 58 is formed as a corresponding member to the female thread 50 of the push rod receiving portion 48 in the load receiving block 36 (see Figure 5).

[0051] The male thread 58 of the push rod 52 is screwed into the female thread 50 of the push rod receiving portion 48, and as a result, the male thread 58 engages with the female thread 50.

[0052] The through-hole 56 extends from the side facing the load-receiving block 36 through the load-transmission section 38 towards the stopper 18.

[0053] Furthermore, Figure 5 shows that the push rod 52 has a stepped portion 60, and this stepped portion 60 is pressed against the interface surface 62 which is oriented downward in the axial direction of the load transmission portion 38 by the spring biasing force, at least when no load is applied to the scale.

[0054] Therefore, the thin plate spring 54 is pressed against the surface of the stepped portion 60 that is opposite to the interface surface 62.

[0055] For example, the thin plate spring 54 is made from spring steel.

[0056] By setting the thickness and / or material of the leaf spring 54, the leaf spring 54 can be configured such that a desired overload is defined for the overload protection unit 16.

[0057] The thin plate spring 54 is firmly connected to the load transmission section 38, for example, by a screw connection.

[0058] Furthermore, the overload protection unit 16 works in cooperation with the stopper 18 to guide the overload back to the casing.

[0059] For this purpose, the stopper 18 is fixed to the lower surface of the base 28, for example, by screw connection.

[0060] Here, the stopper 18 is attached below the base opening 64 (see Figures 2 and 5). The base opening 64 extends completely through the base 28.

[0061] In Figures 1 to 5, the scale 10 can be seen in an unloaded state, and therefore a gap S is formed between the push rod 52 and the stopper 18 in the longitudinal direction of the push rod 52 (see Figure 5).

[0062] When a force resulting from a load smaller than the specified overload acts on the load receiving section 14, this force is further transmitted to the load transmission section 38 via the load receiving block 36, the push rod 52, and the leaf spring 54. Subsequently, the force is transmitted from the load transmission section 38 to the sensor system via the lever system 34 in a known manner.

[0063] As long as the load remains below the specified overload limit, the greater the load, the greater the bending load applied to the leaf spring 54, and therefore the more the leaf spring 54 deflects.

[0064] However, if the load reaches or exceeds the specified overload, the stopper 18 prevents further movement of the push rod 52, and as a result, the difference of the load exceeding the specified overload is diverted through the stopper 18.

[0065] Since the stopper 18 is positioned on the base 28 of the grounding body 22, the aforementioned difference is first led to the grounding body 22, and then to the casing. [Explanation of symbols]

[0066] 10 scales 12 Weighing sensors 14 Load-receiving section 16 Overload protection section 18 Stopper 20 Spacers 22 Grounding body 24 Load introduction section 26 Parallelogram Guide 28 base 30 Parallelogram Links 32 joints 34 Lever type 36 Load-bearing block 38 Load transmission section 40 Parallelogram Guide 42 Parallelogram Link 44 joints 46 openings 48 Push rod receiving part 50 Female threads 52 Pushrods 54. Thin leaf spring 56 Through hole 58 Male screw thread 60 multi-layered section 62 Interface 64 Base opening

Claims

1. A monolithic weighing sensor for a scale, comprising a grounding body (22) and a load introduction section (24) that transitions monolithically to the grounding body (22) via a first parallelogram guide (26), wherein the load introduction section (24) comprises a load receiving block (36) and a load transmission section (38), the load receiving block (36) transitions monolithically to the load transmission section (38) via a second parallelogram guide (40), the load transmission section (38) is further hinged to the first parallelogram guide (26), and the load receiving block (36) is provided with a push rod receiving section (48) for an overload protection section (16).

2. The weighing sensor according to claim 1, characterized in that the first parallelogram guide (26) has two first parallelogram links (30) that pivotably connect the load introduction section (24) to the grounding body (22), the second parallelogram guide (40) has two second parallelogram links (42) that pivotably connect the load receiving block (36) to the load transmission section (38), and the two first parallelogram links (30) are located in a plane substantially perpendicular to the plane in which the two second parallelogram links (42) are located.

3. The weighing sensor according to claim 1, characterized in that the inner wall of the push rod receiving portion (48) in the load receiving block (36) is provided with female threads (50).

4. The weighing sensor according to claim 1, characterized in that the grounding body (22) has a base (28) that extends below the first parallelogram guide (26) and the load introduction section (24).

5. The weighing sensor according to claim 1, characterized in that the second parallelogram guide (40) has two second parallelogram links (42), with one second parallelogram link (42) extending above and below the load receiving block (36).

6. The weighing sensor according to claim 5, characterized in that the second parallelogram link (42) extending above the load receiving block (36) has an opening (46) directed toward the load receiving block (36).

7. An electronic scale comprising a casing and a weighing sensor (12) according to any one of claims 1 to 6, housed in the casing, wherein the grounding body (22) of the weighing sensor (12) is mechanically and firmly connected to the casing, and the casing contains a sensor system for measuring applied force, a stopper (18), and a push rod (52) of the overload protection unit (16), the push rod (52) being received by the push rod receiving unit (48) of the load receiving block (36), extending to the stopper (18), and contacting the stopper (18) when an overload is reached.

8. The scale according to claim 7, characterized in that the push rod (52) of the overload protection section (16) is spring-biased in the direction of the load receiving block (36).

9. The scale according to claim 8, characterized in that the overload protection part (16) includes a leaf spring (54) that spring-bias the push rod (52).

10. The scale according to claim 9, characterized in that the leaf spring is positioned between the load receiving block (36) and the stopper (18) in the longitudinal direction of the push rod (52), and is particularly positioned on the outer surface of the load transmission section (38) facing the stopper (18).

11. The scale according to claim 7, characterized in that the inner wall of the push rod receiving portion (48) of the load receiving block (36) is provided with female threads (50), the free end of the push rod (52) is provided with male threads (58), and the push rod (52) is screwed into the push rod receiving portion (48) of the load receiving block (36), so that the male threads (58) of the push rod (52) engage with the female threads (50) of the load receiving block (36).

12. The scale according to claim 7, wherein the grounding body (22) has a base (28) that extends below the first parallelogram guide (26) and the load introduction section (24), and the stopper (18) is positioned on the base (28) of the grounding body (22) on the imaginary extension line of the push rod (52).

13. The scale according to claim 7, characterized in that the overload protection unit (16) is load-controlled and is located in a force channel between the load receiving block (36) and the sensor system, and when the load is below the overload, the overload protection unit (16) is configured to transmit the force applied to the load receiving block (36) by the load to the sensor system via the load transmission unit (38), and when the load exceeds the overload, the overload protection unit (16) contacts the stopper (18), and the force is discharged via the grounding body (22) and / or the casing.

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