WO2015087146A2

WO2015087146A2 - Liquid level sensor

Info

Publication number: WO2015087146A2
Application number: PCT/IB2014/002728
Authority: WO
Inventors: 宁营杰; 张倩
Original assignee: 大陆汽车有限公司
Priority date: 2013-12-10
Filing date: 2014-12-10
Publication date: 2015-06-18
Also published as: CN203798419U; WO2015087146A3

Abstract

The present utility model relates to a liquid level sensor comprising a circuit board having a resistive strip, a contact-point-producing component, and a float lever assembly. The contact-point-producing component is adapted for causing at least a part of the resistive strip to enter a state of electrical connection to a pre-set circuit on the circuit board. The float lever assembly is adapted for driving, on the basis of a change in the liquid level, the contact-point-producing component to shift, thereby enabling the circuit to output an electrical signal reflecting a change in the liquid level. The invention is characterized in that the contact-point-producing component is provided with a wheel that causes the resistive strip to enter a state of electrical connection. The electrical connection is created as a result of rolling movement produced as the edge of the wheel presses against the resistive strip.

Description

liquid level sensor

Technical field

The utility model relates to a liquid level sensor, in particular to a liquid level sensor for measuring the oil level in a fuel tank of a vehicle. Background technique

The existing liquid level sensor slides the sliding piece on the resistor piece by the float to sense the level of the liquid level. As shown in Fig. 5, the conventional level sensor 10 includes a housing 11 and a rotating body 12 mounted on the housing 11. The housing 11 is provided with a resistor 13, a signal circuit, an input interface and an output interface. The rotating body 12 is provided with a central shaft 14 and a spring 15 connected to a float, and the spring 15 is fixed to the central shaft 14. The liquid level sensor is placed in a container for accommodating the liquid. When the liquid level changes, the position of the float changes, and the sliding contact piece 16 fixed to the rotating body 12 is further driven to move on the resistive piece in the housing 11 to The liquid level change information is converted into resistance change information, and the liquid level signal is output to the corresponding electronic component such as a vehicle meter by the signal circuit and the output interface in the casing 11.

Since the sliding contact piece of the liquid level sensor is slid and rubbed with the resistor piece for a long time, it is extremely easy to wear, and the output resistance is inaccurate. In order to improve the wear resistance of the contacts, the contacts on the slider are mostly made of an expensive metal alloy such as a gold alloy, such as the slider described in the patent document CN202631060U. This makes the manufacturing cost increase.

Not only that, the resistors are immersed in oil for a long time, which is easy to corrode, and is also susceptible to impurities in the oil, resulting in inaccurate output resistance. In order to overcome this problem, the patent document CN203148528U discloses a technical means for avoiding direct contact between the resistor sheet and the oil in the oil tank by using a flexible circuit contact plate placed on the upper portion of the resistor sheet, but the touch of the flexible line contact plate and the rocker arm Long-term sliding friction of the head is still easy to cause damage to the flexible circuit contact plate and wear of the contacts, in addition, due to the contacts The contact with the flexible line contact plate is not stably achieved, and therefore, the output signal of the sensor is unstable.

Further, in the conventional liquid level sensor such as the sensor 10 shown in Fig. 5, the central shaft is subjected to a certain torque during the continuous rotation of the rotary body 12 around the central axis 14. Due to the long-term effect of this torque, the center shaft 14 has a risk of being released from its mounting hole. Therefore, the reliability of the existing liquid level sensor needs to be further enhanced.

The present invention is directed to overcoming one or more of the above problems. Utility model content

It is an object of the present invention to provide a liquid level sensor that enables longer life, higher reliability, less environmental impact, and more accurate output.

According to an aspect of the present invention, a liquid level sensor including a circuit board having a resistance band, a contact forming member, and a float lever assembly configured to bring at least a portion of the resistance band into the circuit board is provided a state in which the preset circuit is electrically connected, the float lever assembly is configured to drive the contact forming member to move based on a change in the liquid level, thereby causing the circuit to output an electrical signal reflecting a change in the liquid level, characterized in that The contact forming member has a roller for bringing the resistance band into an electrical connection state, and the electrical connection is formed by rolling of a rim of the roller against the resistance band.

The level sensor according to the present invention advantageously utilizes rolling friction between the roller and the resistive tape to greatly reduce wear of the sensor components.

In an advantageous embodiment, the circuit board has an electrically conductive and elastic film covering the side of the resistance strip facing the roller to seal the resistance band and to be spaced from the resistance band Settings. With this configuration, the resistor strip is sealed and assembled to avoid direct contact with the oil, avoiding corrosion of the resistor strip or board and the effects of impurities in the oil on the level sensor.

In an advantageous embodiment, the roller is made of plastic. Preferably, for example, the roller is made of a acetal plastic. With this configuration, the manufacturing cost of the liquid level sensor can be reduced, and the components of the sensor can be conveniently mass-produced.

In an advantageous embodiment, the liquid level sensor further includes a bracket having a tubular shape a first arm and a second arm extending from a peripheral wall of the tubular portion, the bracket being rotatable about a central axis of the tubular portion, the first arm being configured for connection with the float, and the second arm for constructing Connected to the contact forming member. With this configuration, the central axis design of the existing liquid level sensor can be omitted, the risk of the center shaft being prevented from coming out, and the assembly operation is simpler and the installation space is more compact.

In an advantageous embodiment, the contact forming member further has an elastic member for preloading the roller with a pressure toward the resistance band. With this configuration, the engagement of the roller with the film covered by the resistor tape or the resistor tape is prevented from being loosened, so that the output of the sensor is more accurate.

In an advantageous embodiment, the contact forming member further has an elastic member for supporting the roller. In combination with the action of the elastic member, the support seat can effectively support the roller to prevent the roller from loosely or too tightly engaging the film on the resistance belt to ensure the stability of the liquid level sensor output.

In an advantageous embodiment, the elastic member is injection molded together with the support by a double injection molding process on the side of the support which faces away from the roller.

In an advantageous embodiment, the second arm of the bracket and the resilient member of the contact forming member are joined together by heat pressing.

In an advantageous embodiment, the film is a CuNi film. The conductivity and elasticity of the CuNi film enable the sensor to operate normally and stably and accurately output a resistance signal.

In an advantageous embodiment, the film is sealingly attached to the circuit board by soldering. Most of the welding methods used are soldering. The resistance band can be tightly sealed with respect to the oil in the tank by welding.

Preferably, the elastic member is a SUS304 elastic piece.

The liquid level sensor according to the present invention has the advantages of: the rolling friction is used instead of the sliding friction in the existing sensor, so that the wear of the sensor component such as the contact forming member is small, and the oil in the oil tank is sealed due to the resistance tape being sealed by the film. Isolation makes it possible to protect the resistance band from the wear of the rollers and from the oil in the tank. The elastic member makes the roller always engage with the resistance band or the film covering the resistance tape with a suitable amount of force, and since the conductive elastic film exists, the contact forming member no longer has to be made of a conductive material such as gold, and therefore can be lowered manufacturing cost. In addition, the liquid level sensor according to the present invention has a compact structure, a small installation space, and is more convenient to be assembled in a fuel tank having a limited space available. DRAWINGS

Embodiments of the present invention are further described below in conjunction with the accompanying drawings. It is to be understood that the dimensions in the drawings do not indicate the true dimensions or proportions of the present invention, and the configuration of the various components does not represent the true configuration of the present invention. The drawings are merely schematic, and certain non-essential elements may be omitted for clarity and conciseness of the views.

1 is an exploded perspective view of a liquid level sensor according to the present invention;

2 is a schematic view showing a connection structure between a contact forming member and a bracket of a liquid level sensor according to the present invention;

3 is a schematic view showing the working principle of the liquid level sensor according to the present invention, wherein the roller is pressed against the resistance band via the film;

Figure 4 is a schematic view showing the installation of a liquid level sensor in a fuel tank according to the present invention, wherein the float and the bracket are connected by a lever member;

Figure 5 shows a general schematic of a prior art level sensor. detailed description

As shown in FIG. 1, an exemplary liquid level sensor 1 of the present invention includes a circuit board mounting frame 2, a circuit board 3, a contact forming member 4, and a bracket 5. The circuit board 3 is mounted on the circuit board mounting frame 2. Preferably, the circuit board 3 is assembled to the circuit board mounting frame 2 by means of a bayonet positioning. The circuit board 3 has a resistor sheet 30 on which a resistor tape 300 is printed. The resistance band 300 is designed to be capable of electrically connecting the resistance band of the corresponding portion into a state of being electrically connected to a predetermined circuit in the circuit board 3 when the contact forming member 4 is pressed against a certain position of the resistance band, and the circuit output of the circuit is turned on. The resistance value corresponding to the position. Further, the resistance value is converted by the conversion circuit into an electrical signal output indicating the liquid level. For convenience of explanation, herein, a position on the resistance band 300 that is pressed against the contact forming member 4 is referred to as a contact, and is configured to be in direct or indirect contact with the resistance band to allow at least a portion of the resistance band to enter the circuit board. A part of a state in which a predetermined circuit is electrically connected is called a touch The dots form a part. A part of the resistance band corresponding to the contact is connected to the preset circuit through the wire drawn from the contact, and the part of the resistance band is brought into an electrical connection state. As the contact forming member 4 moves, the formed contacts also move over the resistive strip 300, so that different sections of the resistive strip enter an electrical connection state, thereby outputting an electrical signal indicative of the corresponding liquid level.

Here, the movement of the contact forming member 4 is driven by the float lever assembly 6 (shown in Fig. 4) of the level sensor 1. The float lever assembly 6 includes a float 60 and a float lever member 61 coupled to the float. When the liquid level changes, the float 60 will rise or fall accordingly, thereby causing the float lever member 61 to move, and the movement is transmitted to the contact forming member 4, so that the contact forming member 4 moves according to a predetermined movement trajectory, that is, The contact forming member 4 is always kept moving within the usable area or effective range of the resistance band. In the case where the contact forming member is configured to be electrically conductive, the wire drawn from the contact and connected to the predetermined circuit loop may be configured to be drawn out from the contact forming member.

The contact forming member 4 shown in Fig. 1 has a scrollable rolling member such as a roller 40. The support base 41 is provided for supporting the roller 40. The stub shafts 401, 402 projecting from both sides of the roller 40 are fitted into the mounting holes 411, 412 of the support block 41 with a clearance fit. The roller 40 is rotatable about its axis in the recessed space of the support base 41 without interfering with the support. The roller configuration shown in Figure 1 is merely exemplary, and those skilled in the art will readily appreciate that the rolling members may be balls, rolling rings, etc., and the rollers may be designed to have more than one rim or roller for resisting resistance. With contact.

The level sensor 1 may also include an elastic member 42 for preloading the roller with a pressure toward the resistance band 300. In the illustrated embodiment, the resilient member 42 is a resilient piece, preferably a SUS 304 spring. The elastic piece is mounted on a side of the support base 41 facing away from the roller 40 for applying a biasing force to the support base and the roller, so that the roller 40 is pressed against the resistance band 300 with a suitable amount of force to engage the contact strip with the resistance band. And will not loose. This biasing force can be obtained by biasing the shrapnel when the shrapnel is mounted.

Although the support base 41 is shown in a "hood" configuration in FIG. 1, it will be readily apparent to those skilled in the art that the support base 41 can also be designed in a "bracket" configuration, as long as the roller rim can Extend and press against the resistance band. Although the shrapnel is shown as having a U-shaped general structure, However, those skilled in the art will readily appreciate that other shapes of shrapnel, such as annular, triangular shrapnel, are equally suitable for use in the present invention. The elastic member is of course not limited to the illustrated elastic configuration. For example, the elastic member 42 can also be designed as a coil spring, a coil spring, a reed or the like. The elastic member may also be disposed inside the cover-like support and act on the short shafts 401, 402 of the roller to apply a biasing force. By reasonably designing the structural properties of the elastic member, the mounting method, and the degree of bias, the biasing force applied to the roller can be controlled within an appropriate range.

The liquid level sensor shown in Fig. 1 further includes a bracket 5 having a cylindrical portion 50 and a first arm 51 and a second arm 52 projecting from the peripheral wall of the cylindrical portion. The bracket 5 is rotatable about a central axis of the cylindrical portion. The first arm 51 is configured for connection with the lever assembly 6 (shown in Figure 4) and the second arm 52 is configured for connection with the contact forming member 4 (shown in Figure 2). As can be seen from Fig. 1, the end of the first arm 51 is formed with a recess for accommodating the float lever member 61 (as shown in Fig. 4), whereby the movement of the float lever member 61 can be transmitted. The bracket 5 is rotated to rotate the bracket 5 about its central axis, causing the second arm 52 to rotate and move the contact forming member 4, thereby causing the roller 40 to be pressed against the resistance band 300, thereby outputting different resistance values and indicating different The electrical signal of the liquid level.

Specifically, in conjunction with Figs. 1 and 2, the end of the second arm 52 is provided with three pins 520, and the spring piece 42 is correspondingly provided with three pin holes 420. The second arm 52 and the elastic piece 42 are joined by pressing the pin 520 into the pin hole 420 by, for example, hot pressing. In this embodiment, the number and distribution of pin holes or pins are exemplary, and other arrangements are also readily apparent to those skilled in the art. Of course, the manner of connection between the elastic piece 42 and the second arm 52 is not limited to the manner shown, for example, it can be connected by other conventional connection means such as splicing. It will also be appreciated by those skilled in the art that the second arm and the shrapnel are integrally formed, for example, the second arm is constructed as an elastic member having a biasing force.

In the preferred embodiment shown in FIG. 1, the circuit board 3 has an electrically conductive and resilient film 31 which covers the side of the resistance strip 300 facing the roller 40 to seal the resistive strip and the resistive strip 300 interval setting, as shown in Figure 3. The roller 40 is pressed against the resistive tape 300 against the film 31 under the biasing force F from the shrapnel, so that the film is deformed until the film 31 abuts against the resistive tape 300, and a contact is formed on the resistive tape 300. With the scrolling of the roller 40, touch The dots are formed at different positions of the resistance band. Since the film is elastic, after the roller is removed, the film rebounds to the original contact position to be spaced apart from the resistance band, so that only the resistance band 300 is pressed against the roller 40 during the rolling process of the roller. The corresponding position produces a contact. In this embodiment, since the film 31 has electrical conductivity, the wires taken out from the contacts and connected to the respective circuits can be configured to be taken out from the film. In this configuration, the rollers do not have to be made of a conductive metal material, In particular, the rim of the roller does not have to be made of a wear-resistant and expensive gold alloy material. The film 31 is preferably a CuNi film. Preferably, the film 31 is soldered to the resistor sheet 3 by means of tin crucible. In this embodiment, the roller 40 can be made of a plastic such as acetal plastic (POM-C). Accordingly, both the support base 41 and the bracket 5 can be made of plastic such as acetal plastic. In the illustrated embodiment, the support block 41 can be injection molded together with the shrapnel 42 by overmolding. The connection between the shrapnel 42 and the second arm 52 of the bracket 5 can be achieved, for example, by hot pressing.

With continued reference to FIG. 4, it can be seen that the installed liquid level sensor 1 according to the present invention is compact in structure compared to the existing liquid level sensor, has a small installation space, and does not interact with the oil pipe in the oil supply system assembly. The wire line interferes. Industrial applicability

To facilitate understanding of the level sensor of the present invention, the assembly and installation process of the exemplary level sensor of the present invention is described below:

The film is covered on the resistor sheet and spaced apart from the resistor sheet, and the edge of the film is twisted onto the resistor sheet to seal the resistor sheet, thereby forming a circuit board, and the assembled circuit board is mounted to the board mounting skeleton Upper, secure the board with the bayonet positioning device. The bearing seat and the elastic piece are injection molded together by a double injection molding method, and then the roller is pressed into the groove of the support seat by means of a clearance fit, and then the pin hole on the elastic piece and the pin on the second arm of the bracket pass Hot pressing is connected together. Fixing the circuit board mounting frame and the bracket to the fuel tank casing in a predetermined relative positional relationship, so that the spring piece is in a rolling state, whereby the spring piece always applies a biasing force to the bearing seat, and the biasing force is transmitted to the roller and On the board that is in contact with the wheel rim. A float lever member is mounted on the groove of the first arm of the bracket, and a float is attached to one end of the float lever member away from the bracket. Thereby, the assembly and installation process of the liquid level sensor is completed. The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Those skilled in the art can make various kinds of devices of the present invention without departing from the scope of the present invention. Improvements and variants. Other embodiments may also be derived by those skilled in the art from consideration of the disclosure herein. The description and illustration are to be considered as illustrative only,

Claims

Claim

CLAIMS 1. A level sensor comprising a circuit board having a resistive strip, a contact forming member and a float lever assembly, the contact forming member configured to electrically connect at least a portion of the resistive strip into a predetermined circuit in the circuit board a state, the float lever assembly is configured to drive the contact forming member to move based on a change in the liquid level, thereby causing the circuit to output an electrical signal that changes a reaction level, wherein the contact forming member has a function The roller is brought into an electrically connected state, and the electrical connection is formed by rolling of a rim of the roller against the resistance band.

The liquid level sensor according to claim 1, wherein the circuit board has an electrically conductive and elastic film, and the film covers a side of the resistance band facing the roller to seal the A resistor strip is disposed spaced from the resistor strip.

The liquid level sensor according to claim 2, wherein the roller is made of plastic.

The liquid level sensor according to any one of claims 1 to 3, wherein the liquid level sensor further comprises a bracket having a cylindrical portion and a first arm extending from a peripheral wall of the cylindrical portion And the second arm, the bracket is rotatable about a central axis of the cylindrical portion, the first arm is configured to be coupled to the float, and the second arm is configured to be coupled to the contact forming member.

The liquid level sensor according to any one of claims 1 to 3, wherein the contact shape

The liquid level sensor according to claim 4, wherein the contact forming portion is loaded with an elastic member that faces the pressure of the resistance band.

The liquid level sensor according to claim 6, wherein the elastic member is injection molded with the support base by a double injection molding method on a side of the support seat facing away from the roller.

The liquid level sensor according to claim 6 or 7, wherein the second arm The elastic members of the contact forming member are joined together by heat pressing.

The liquid level sensor according to claim 2 or 3, wherein the film is CuNi

10. The liquid level sensor according to claim 2, wherein the film is sealingly connected to the circuit board by soldering.

The liquid level sensor according to claim 6 or 7, wherein the elastic member is a SUS304 elastic piece.

The liquid level sensor according to claim 3, wherein the roller is made of a paraformaldehyde plastic.