CN112213024A

CN112213024A - Knock sensor

Info

Publication number: CN112213024A
Application number: CN201910617820.8A
Authority: CN
Inventors: 牛东
Original assignee: Vitesco Automotive Changchun Co Ltd
Current assignee: Vitesco Automotive Changchun Co Ltd
Priority date: 2019-07-10
Filing date: 2019-07-10
Publication date: 2021-01-12

Abstract

The present invention provides a knock sensor including: the carrier comprises a base and a tubular part extending from the upper surface of the base along the axial direction, wherein a convex part protruding outwards in the radial direction is arranged on the tubular part, and a first preset distance is reserved between the convex part and the base; the electronic components comprise a first insulating ring, a first conducting ring, a piezoelectric element, a second conducting ring and a second insulating ring which are sequentially sleeved on the tubular part from bottom to top and are positioned between the base and the convex part; a weight ring disposed above the plurality of electronic components and elastically deformable; and a wedge ring clamped between the boss and the counterweight ring. The knock sensor provided by the invention omits fine threads with high machining precision requirement, thereby simplifying the structure and reducing the cost.

Description

Knock sensor

Technical Field

The invention relates to a knock sensor, in particular to a piezoelectric knock sensor.

Background

Knocking is an abnormal combustion phenomenon occurring during operation of the internal combustion engine, which disadvantageously causes excessive temperature, increased fuel consumption, abnormal rotation speed, and the like of the internal combustion engine. Since the cylinder of the internal combustion engine generates vibration of different degrees when knocking occurs, the knocking intensity can be determined according to the vibration frequency change of the cylinder, so that the ignition advance angle and the like can be adjusted accordingly, and the occurrence of knocking and the possible harm caused by the knocking can be reduced.

The knock sensor is an electronic sensor mounted on a cylinder block of an internal combustion engine and used for detecting a knocking phenomenon of the internal combustion engine. A typical knock sensor of the related art is shown in fig. 1, and includes a plastic housing 8 'and an electronic component assembly fixed in the plastic housing 8'. When manufacturing the knock sensor, the components of the electronic component assembly are pre-fixed together, and then the electronic component assembly is placed in an injection mold, and the plastic shell 8' is manufactured by means of over-molding. The electronic component assembly comprises a carrier 1 ', a plurality of electronic components, a counterweight ring 5 ' and a nut 9 ', wherein the plurality of electronic components comprise: a first insulating ring 21 ', a first conductive ring 31 ', a piezoelectric element 4 ', a second conductive ring 32 ', a second insulating ring 22 '. The carrier 1 'is made of a metal material and includes a base 11' and a tubular portion 12 'extending upward in an axial direction from an upper surface of the base 11'. A central through hole is formed through the base 11 ' and the tubular portion 12 ' and a bolt can pass through the central through hole to fix the knock sensor to the cylinder surface of the internal combustion engine so that the bottom end surface of the base 11 ' is in direct contact with the cylinder of the internal combustion engine. The tubular portion 12 'is provided with a projection 121' projecting radially outward, an outer peripheral wall of the projection 121 'is provided with a fine thread, and an inner peripheral wall of the nut 9' is provided with a fine thread. The protrusion 121 'and the nut 9' are screwed together by fine threads, so that the first insulating ring 21 ', the first conductive ring 31', the piezoelectric element 4 ', the second conductive ring 32', the second insulating ring 22 ', and the weight ring 5' are fixed between the base 11 'and the nut 9', and the pre-fixing of the electronic component assembly is realized.

The operating principle of the knock sensor is as follows: when the cylinder body of the internal combustion engine vibrates, the vibration is transmitted to the balancing weight 5 ' through the carrier 1 ' and the nut 9 ', the balancing weight 5 ' applies acting force to the piezoelectric element 4 ' under the vibration action, so that the piezoelectric element 4 ' generates voltage based on the piezoelectric effect, the voltage is transmitted to a lead through the first conducting ring 31 ' and the second conducting ring 32 ' which are positioned on two sides of the piezoelectric element 4 ', and then is transmitted to the external control module, and the external control module judges the knocking intensity according to the voltage value.

In the knock sensor described above, the respective elements in the electronic component assembly are fastened together by screwing the protrusion 121 'to the fine thread of the nut 9'. The high machining precision requirement of the fine thread results in high cost of the knock sensor.

Disclosure of Invention

The invention aims to provide a knock sensor with simple structure and low cost.

According to an aspect of the present invention, there is provided a knock sensor including: the carrier comprises a base and a tubular part extending from the upper surface of the base along the axial direction, wherein a convex part protruding outwards in the radial direction is arranged on the tubular part, and a first preset distance is reserved between the convex part and the base; the electronic components comprise a first insulating ring, a first conducting ring, a piezoelectric element, a second conducting ring and a second insulating ring which are sequentially sleeved on the tubular part from bottom to top and are positioned between the base and the convex part; a weight ring disposed above the plurality of electronic components and elastically deformable; and a wedge ring clamped between the boss and the weight ring.

In one embodiment, the wedge ring is a C-ring having a circumferential gap. Preferably, the counterweight ring is a C-shaped ring with a circumferential gap. Further preferably, the circumferential notch of the wedge ring is arranged at substantially the same circumferential position as the circumferential notch of the counterweight ring.

In one embodiment, the inner circumferential wall of the counterweight ring is spaced a second predetermined distance from the outer circumferential wall of the tubular portion; the wedge ring has a first end extending into the inner bore of the counterweight ring and a second end located outside the inner bore of the counterweight ring; the outer peripheral wall of the wedge-shaped ring is provided with a first wedge surface which is in contact with the counterweight ring in an abutting mode; the end surface of the second end of the wedge-shaped ring is in abutting contact with the end surface of the convex part facing the base.

In one embodiment, a smooth transition portion is arranged between the inner peripheral wall of the counterweight ring and the end surface of the counterweight ring far away from the base, and the smooth transition portion is in pressing contact with the first wedge surface of the wedge-shaped ring.

In one embodiment the inner circumferential wall of the wedge ring is provided with a second wedge surface which is a sliding fit with the outer circumferential wall of the protrusion during mounting of the wedge ring.

In one embodiment the projection is provided with a wedge-shaped guide surface at the end remote from the base.

In one embodiment, the wedge ring has a substantially triangular cross-section, and three sides of the triangle are located at a plane corresponding to the first wedge surface, the second wedge surface and the second end surface, respectively.

In one embodiment, an annular cavity is formed between the inner circumferential walls of the first insulating ring, the first conductive ring, the piezoelectric element, the second conductive ring and the second insulating ring and the outer circumferential wall of the tubular part, and the annular cavity is communicated with the circumferential gap of the counterweight ring and/or the circumferential gap of the wedge-shaped ring.

In one embodiment, the peripheral wall of the base is provided with a first relief structure, the peripheral wall of the tubular portion is provided with a second relief structure, and the projection is located axially between the second relief structure and the base.

In one embodiment, the knock sensor further includes a plastic housing formed by injection molding and securing the first insulating ring, the first conductive ring, the piezoelectric element, the second conductive ring, the second insulating ring, the counterweight ring, the wedge ring, and the carrier together.

When the knock sensor is manufactured, after the first insulating ring, the first conducting ring, the piezoelectric element, the second conducting ring, the second insulating ring and the counterweight ring are sequentially arranged at the position between the base and the convex part, the wedge-shaped ring is pressed between the counterweight ring and the convex part, so that the counterweight ring is compressed to generate elastic deformation, and all elements are firmly combined together. The resilient restoring force of the counterweight ring also clamps the wedge ring between the boss of the tubular portion of the base and the counterweight ring. The pre-fixing of the electronic component assembly of the knock sensor saves fine threads with high machining precision requirements, so that the structure of the knock sensor is simplified, and the cost of the knock sensor is reduced.

Drawings

Fig. 1 schematically shows a cross-sectional structure of a knock sensor in the related art;

fig. 2 schematically shows a cross-sectional structure of a knock sensor of an embodiment of the invention;

FIG. 3 schematically illustrates a three-dimensional structure in which electronic component assemblies in a knock sensor according to an embodiment of the invention are assembled together;

FIG. 4 schematically illustrates an exploded structure of an electronic component assembly in a knock sensor according to an embodiment of the invention;

fig. 5 schematically shows a partial perspective view of a knock sensor according to an embodiment of the present invention.

Detailed Description

Referring to fig. 2 to 5, a knock sensor provided by an embodiment of the present invention is shown, which includes a plastic housing 8 and an electronic component assembly packaged in the plastic housing 8. The electronic component assembly includes a carrier 1, a weight ring 5, and a wedge ring 6, and a plurality of electronic components, such as a first insulating ring 21, a first conductive ring 31, a piezoelectric element 4, a second conductive ring 32, and a second insulating ring 22. As is known in the art, the plastic housing 8 is formed by injection molding and holds the electronic component assembly together. Specifically, in the manufacturing process of the knock sensor, the respective constituent elements of the electronic component assembly are first pre-fixed together, and then the electronic component assembly is placed in an injection mold, and the plastic case 8 coated on the electronic component assembly is molded by injecting an injection molding material such as resin into the injection mold.

The carrier 1 includes a base 11 and a tubular portion 12 extending in an axial direction from an upper surface of the base 11. As an example, the carrier 1 may be made of a metallic material. The outer peripheral wall of the tubular portion 12 is provided with a projection 121 projecting radially outwardly, the projection 121 being spaced from the base 11 by a first predetermined distance (axial distance) so as to form a groove structure on the outer peripheral wall of the tubular portion 12 between the projection 121 and the base 11. A center through hole 10 penetrates the base 11 and the tubular portion 12 so that a bolt can pass through the center through hole 10 to fix the knock sensor to the cylinder surface of the internal combustion engine.

The first insulating ring 21, the first conductive ring 31, the piezoelectric element 4, the second conductive ring 32, and the second insulating ring 22, which are electronic components of the knock sensor, are sequentially sleeved on the tubular portion 12 of the carrier 1 from bottom to top and are located between the base 11 and the convex portion 121 in the axial direction. As an example, the first insulating ring 21 and the second insulating ring 22 may be made of glass fiber; the first conductive ring 31 and the second conductive ring 32 may be made of CuZn 37; the piezoelectric element 4 may be a piezoelectric ceramic, and specifically, may be a lead zirconate titanate piezoelectric ceramic. It will be appreciated by those skilled in the art that the electronic components described above may also be made of any other suitable material.

The weight ring 5 is disposed above the second insulating ring 22 and is elastically deformable. In the present embodiment, referring to fig. 3 and 4, the counterweight ring 5 is configured as a C-ring having a circumferential gap 50, for example similar in material and configuration to a C-spring washer. The counterweight ring 5 has simple structure, easy manufacture and low cost. The manner of realizing the elastic deformation of the weight ring 5 is not limited to this. For example, in one embodiment, not shown, the counterweight ring 5 may be configured as a belleville spring.

When the electronic component assembly of the present embodiment is assembled, first, the first insulating ring 21, the first conductive ring 31, the piezoelectric element 4, the second conductive ring 32, the second insulating ring 22 and the weight ring 5 are sequentially sleeved on the tubular portion 12 and are disposed in the groove structure between the base 11 and the protrusion 121. Then, the wedge ring 6 is pressed between the convex portion 121 and the weight ring 5, so that the weight ring 5 is compressed and deformed. Under the elastic restoring force of the weight ring 5, the wedge ring 6 is clamped between the convex portion 121 and the weight ring 5, and then the first insulating ring 21, the first conductive ring 31, the piezoelectric element 4, the second conductive ring 32, the second insulating ring 22, the weight ring 5 and the wedge ring 6 are firmly clamped between the base 11 and the convex portion 121, thereby realizing the pre-fixing and flexible assembly of the electronic component assembly. The pre-fixing of the electronic component assembly of the knock sensor provided by the embodiment omits a fine thread with high machining precision requirement, but uses the wedge-shaped ring 6 with lower machining precision requirement and the counterweight ring 5 capable of elastically deforming, so that the structure of the knock sensor is simplified, the cost of the knock sensor is reduced, and the stable output performance of the knock sensor is ensured.

Referring again to fig. 2, a preferred embodiment of the wedge ring 6 is shown. As an example, the wedge ring 6 may be made of a low carbon steel material. As shown in fig. 2, the inner circumferential wall of the weight ring 5 is spaced from the outer circumferential wall of the tubular portion 12 by a second predetermined distance (radial distance). The wedge ring 6, which is clamped between the weight ring 5 and the protrusion 121, has a first end that extends into the inner bore of the weight ring 5 and a second end that is located outside the inner bore of the weight ring 5. The outer peripheral wall of the wedge-shaped ring 6 is provided with a first wedge surface 61, and the first wedge surface 61 is in pressing contact with the counterweight ring 5; the second end face 63 of the wedge ring 6 is in pressing contact with an end face (not numbered in the figure) of the protrusion 121 facing the base 11. Thus, after the wedge ring 6 is pressed into place, the protrusions 121 prevent the wedge ring 6 from moving away from the counterweight ring 5, and the counterweight ring 5 can naturally abut against the first wedge surfaces 61. Therefore, the requirement on the machining precision of the wedge-shaped ring 6 can be further reduced, and the flexible assembly of the electronic component assembly is realized. Preferably, a smooth transition portion 51 is provided between the inner peripheral wall of the counterweight ring 5 and the end surface of the counterweight ring 5 far from the base 11, and the counterweight ring 5 is in sliding fit and pressing contact with the first wedge surface 61 through the smooth transition portion 51.

In this embodiment, the wedge ring 6 is a C-shaped ring having a circumferential notch 60, so that when the wedge ring 6 is press-fitted, the circumferential notch 60 of the wedge ring 6 can be opened to a certain extent so that the wedge ring 6 passes through the protrusion 121. It will be appreciated that the circumferential gap 60 of the wedge ring 6 is naturally retracted in the closing direction when the wedge ring 6 passes the protrusion 121 and is press-fitted in place. In the present embodiment, the circumferential notch 60 of the wedge ring 6 is arranged at substantially the same circumferential position as the circumferential notch 50 of the weight ring 5, as shown in fig. 3 and 4. This further facilitates the press-fitting of the wedge ring 6. However, in other embodiments, the circumferential gap 60 of the wedge ring 6 and the circumferential gap 50 of the weight ring 5 may be circumferentially offset.

The inner circumferential wall of the wedge ring 6 is provided with a second wedge surface 62. The second wedge surface 62 is in sliding engagement with the outer peripheral wall of the protrusion 121 during installation of the wedge ring 6, and helps the wedge ring 6 to deform as it passes the protrusion 121, thereby making it easier to press-fit the wedge ring 6 into place. Further, a wedge-shaped guide surface 122 may be provided between the outer peripheral wall of the protrusion 121 and the end surface of the protrusion 121 remote from the base 11, and the wedge-shaped guide surface 122 may be capable of guiding press-fitting of the wedge ring 6 in cooperation with the second wedge surface 62 during installation of the wedge ring 6.

In the preferred construction of the wedge ring 6 shown in this embodiment, the cross-sectional profile of the wedge ring 6 is substantially triangular, with three sides of the triangle being located in a plane corresponding to the first wedge surface 61, the second wedge surface 62 and the second end surface 63, respectively. It is understood that it is within the scope of the present application to transition every two adjacent sides of the triangle through a circular arc. As an example, the wedge ring 6 has a cross-sectional profile substantially in the shape of an isosceles triangle. Of course, the cross-sectional shape of the wedge ring 6 is not limited to a triangle, but may also be a trapezoid, in particular an isosceles trapezoid, or other suitable shapes, for example.

It is understood that there are many other embodiments of the wedge ring 6 that can be stably clamped between the weight ring 5 and the protrusion 121 to compress the weight ring 5 and thus the electronic component assembly as a stable whole.

In the present embodiment, the first conductive ring 31 is configured with a first terminal (not numbered), and the second conductive ring 32 is configured with a second terminal (not numbered). For example, after the wedge ring 6 is press-fitted into place (i.e., the wedge ring 6 is clamped between the weight ring 5 and the protrusion 121) and before the electronic component assembly is placed in the injection mold, the first and second terminals are fixed in place on the corresponding first and second

conductive rings

31 and 32, respectively, by, for example, welding, and then the integral injection molding is performed to form the plastic housing 8 integrated with the electronic component assembly, thereby completing the production of the final product. In some embodiments, the first and second terminals are electrically connected to the external control module by wires passing through the plastic housing 8.

Referring again to fig. 2, in the present embodiment, preferably, an annular cavity 100 is formed between the inner circumferential walls of the first insulating ring 21, the first conductive ring 31, the piezoelectric element 4, the second conductive ring 32 and the second insulating ring 22 and the outer circumferential wall of the tubular portion 12, and the annular cavity 100 is communicated with the circumferential gap 50 of the weight ring 5 and the circumferential gap 60 of the wedge ring 6. In this way, during injection molding, the resin solution can enter the annular cavity 100 through the circumferential gap 50 and the circumferential gap 60 and form an insulation. The insulation can on the one hand fill the entire annular cavity 100 to provide effective insulation and on the other hand effectively fix the relative position between the components of the electronic component assembly.

Preferably, the outer peripheral wall of the base 11 is provided with a first relief structure 112, and the outer peripheral wall of the tubular portion 12 is provided with a second relief structure 123. Preferably, the second concave-convex structure 123 is disposed at an end of the tubular portion 12 opposite to the base 11, and the convex portion 121 is located between the second concave-convex structure 123 and the base 11. Through setting up first concave-convex structure 112 and second concave-convex structure 123, both can increase the cohesion between plastic casing 8 and the carrier 1, can play waterproof effect again.

It will be understood that the above embodiments of the present invention are merely exemplary embodiments that have been employed to illustrate the principles of the present invention, and that the present invention is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention, and these changes and modifications are also considered to be within the scope of the invention. The scope of the invention is to be defined only by the meaning of the language of the following claims and by the equivalents thereof.

Claims

1. A knock sensor, comprising:

the carrier (1) comprises a base (11) and a tubular part (12) extending from the upper surface of the base (11) along the axial direction, wherein a convex part (121) protruding outwards along the radial direction is arranged on the tubular part (12), and a first preset distance is reserved between the convex part (121) and the base (11);

the electronic components comprise a first insulating ring (21), a first conductive ring (31), a piezoelectric element (4), a second conductive ring (32) and a second insulating ring (22), wherein the first insulating ring (21), the first conductive ring (31), the second conductive ring (32) and the second insulating ring (22) are sequentially sleeved on the tubular part (12) from bottom to top and are positioned between the base (11) and the convex part (121); and

a weight ring (5), the weight ring (5) being disposed above the plurality of electronic components and being elastically deformable,

characterized in that the knock sensor further comprises a wedge ring (6), the wedge ring (6) being clamped between the protrusion (121) and the counterweight ring (5).

2. The knock sensor according to claim 1,

the wedge-shaped ring (6) is a C-shaped ring with a circumferential notch (60).

3. The knock sensor according to claim 2,

the counterweight ring (5) is a C-shaped ring with a circumferential gap (50).

4. The knock sensor according to claim 3,

the circumferential notch (60) of the wedge ring (6) and the circumferential notch (50) of the counterweight ring (5) are arranged at substantially the same circumferential position.

5. The knock sensor according to any one of claims 1 to 4,

the inner circumferential wall of the counterweight ring (5) is spaced from the outer circumferential wall of the tubular part (12) by a second preset distance;

the wedge-shaped ring (6) is provided with a first end extending into the inner hole of the counterweight ring (5) and a second end positioned outside the inner hole of the counterweight ring (5);

the outer peripheral wall of the wedge-shaped ring (6) is provided with a first wedge surface (61), and the first wedge surface (61) is in pressing contact with the counterweight ring (5);

the second end face (63) of the wedge ring is in pressing contact with the end face of the convex portion (121) facing the base (11).

6. The knock sensor according to claim 5, wherein a rounded transition (51) is provided between the inner circumferential wall of the counterweight ring (5) and an end surface of the counterweight ring (5) remote from the base (11), the rounded transition (51) being in pressing contact with the first wedge surface (61) of the wedge ring (6).

7. The knock sensor according to claim 5, wherein an inner circumferential wall of the wedge ring (6) is provided with a second wedge surface (62), the second wedge surface (62) being in sliding fit with an outer circumferential wall of the protrusion (121) during installation of the wedge ring (6).

8. Knock sensor according to claim 7, where the protrusion (121) is provided with a wedge-shaped guide surface (122) at the end remote from the base (11).

9. Knock sensor according to claim 7, where the wedge ring (6) has a triangular cross-section, where three sides of the triangle are located in a plane corresponding to the first wedge surface (61), the second wedge surface (62) and the second end surface (63), respectively.

10. A knock sensor according to claim 3 or 4, wherein an annular cavity (100) is formed between the inner circumferential walls of the first insulating ring (21), the first conductive ring (31), the piezoelectric element (4), the second conductive ring (32) and the second insulating ring (22) and the outer circumferential wall of the tubular part (12), the annular cavity (100) communicating with the circumferential notch (50) of the counterweight ring (5) and/or the circumferential notch (60) of the wedge ring (6).

11. The knock sensor according to any one of claims 1 to 4, wherein an outer peripheral wall of the base (11) is provided with a first concavo-convex structure (112), an outer peripheral wall of the tubular portion (12) is provided with a second concavo-convex structure (123), and the convex portion (121) is located between the second concavo-convex structure (123) and the base (11) in the axial direction.

12. The knock sensor according to any one of claims 1 to 4, further comprising a plastic housing formed by injection molding and fixing the first insulating ring (21), the first conductive ring (31), the piezoelectric element (4), the second conductive ring (32), the second insulating ring (22), the weight ring (5), the wedge ring (6), and the carrier (1) together.