GB2492886A

GB2492886A - Control system for blade teeth of a cutting tool

Info

Publication number: GB2492886A
Application number: GB201212230A
Authority: GB
Inventors: Fangjie Nie; Zheng Geng
Original assignee: Chevron HK Ltd
Current assignee: Chevron HK Ltd
Priority date: 2011-07-14
Filing date: 2012-07-10
Publication date: 2013-01-16
Anticipated expiration: 2032-07-10
Also published as: GB201212230D0; DE202012102594U1; GB2492886B; FR2977760A3; FR2977760B3; CN102388753B; CN102388753A

Abstract

The present invention discloses a control system for the blade teeth superposition of a cutting tool, which comprises a housing 1 and double blades 6, 7, and at least one switch. A motor control circuit and a blade position detecting device are arranged in the housing, the motor control circuit detecting the position of the blades and controlling the blades to stop when the teeth are superimposed when the at least one switch is switched off. The blade position detecting device may comprise a Hall element 3 arranged in the housing and a magnet 4 provided on the blade. The control system and method for the blade teeth superposition of the cutting tool allows for an object to be cut to be disengaged from the tool. The superimposition of the blades also acts as a safety feature.

Description

A CONTROL SYSTEM FOR THE BLADE TEETH SUPERPOSITION OF A CUTTING

TOOL

Technical Field of the Invention

This invention relates to a control system for the blade teeth superposition of a cutting tool having two blades, which belongs to the technical field of the electric tool.

Background of the Invention

Cutting tools having two blades, such as a hedge trimmer, often stop rotation because the object to be cut is hard to cut in the cutting process. At that moment,the branch is blocked between a fixed blade and a movable blade so that the machine can not get out, thereby affecting a further cutting. If a user removes the branch by hand, he/she is likely to touch the blades and may get hurt. Furthermore, many cutting tools have two switches, that is, a major switch and a subsidiary switch. When the two switches arc both closed, the cutting tool may rotate and cut; when either switch is released, most products may be set to he braked immediately. The cutting tool is then stopped immediately, and the fixed blade often crosses the movable blade, as shown in Fig.2.

Since the sharp movable blade may be exposed outside of the blunt fixed blade, people, especially children, may be hurt when they touch the blade.

Summary of the Invention

One technical problem to be solved by the present invention is to provide a cutting tool, which is easy to be disengaged from the object to be cut once it locks the object in the cutting proccss.

Another technical problem to be solved by the present invention is to avoid a potential safety hazard to the surrounding people or objects when thc sharp blade tecth are exposed outside of the blunt blade in the storage of the tool.

If the teeth of the fixed blade and the movable blade are superposed automatically when either switch is released, the above problems will be solved.

In order to solve the above problems, the present invention provides a control system for the blade teeth superposition of a cutting tool, which comprises a housing and double blades, and at least one switch, wherein a motor control circuit and a blade position detecting device are arranged in the housing, the motor control circuit detecting the position of the blades by the blade position detecting device and controlling the double blades to stop on a superposed position when the at least one switch is off According to the preceding control system for the blade teeth superposition of the cutting tool, wherein the blade position detecting device comprises a Hall element arranged in the housing of thetooLand-a-magneLprovidedomthe-blades.

According to the preceding control system for the blade teeth superposition of the cutting tool, wherein the motor control circuit comprises a MCU which thc Hall element is connected to, the MCU bcing connected to the motor by each drive module.

According to the preceding control system for the blade teeth superposition of the cutting tool, wherein each drive module is connected to the motor by a transistor.

According to thefl preceding control system for the blade teeth superposition of the cutting tool, wherein the MCU is connected to a battery voltage detecting circuit, a battery current detecting circuit, and a current detecting circuit simultaneously.

A control method for the control system for the blade teeth superposition of the cuffing tool, wherein it comprises the following steps: 1) the MCU in the motor control circuit detecting whether a major switch or a subsidiary switch is released at any moment in the process of the cutting tool rotating in the positive direction; 2) the MCII controlling the cutting tool to stop from a positive rotation status immediately and enter into a reverse rotation, status if it is detected that either of the major switch and the subsidiary switch is released; 3) the MCU (microprocessor control unit) detecting the position of a first blade by the Hall element and the magnet on the first blade in the period of the reverse rotation status, and controlling the cutting tool to stop from the reverse rotation status if the blade teeth of the two blades are superposed so that a blade teeth superposition is achieved.

According to the preceding control method for the control system for the blade teeth superposition of the cutting tool, wherein in the step 3), a low level is outputted by the Hall elementavhen_theMlade_teeth_otthe_two_Madesare: supcrposed_anda_high1evel_i&outputted_by the Hall element when the blade teeth of the Iwo blades are not superposed.

According to the preceding control method for the control system for the blade teeth superposition of the cutting tool, wherein it further comprises before the step 1) the step of detecting whether the current, the voltage and the temperature of the battery exceed the limit, entering the step 1) if the current, the voltage and the temperature of the battery do not exceed the limit; and sending an alarm message, stopping the output of the positive rotation of the motor, entering the reverse rotation status, and repeating the step 3) if one or more of the current, the voltage and the temperature of the battery exceed the limit.

According to the preceding control method for the control system for the blade teeth superposition of the cutting tool, wherein the cutting tool is controlled in accordance with the step 2) and the step 3) if either of the major switch and the subsidiary switch is releascd in the step of detecting whether the current, the voltage and the temperature of the battery exceed the limit.

In the control system and the control method for the blade teeth superposition of the cutting tool according to the present invention, the position of the movable blades can be detected by the Hall element, hence, once the cutting tool does not work when cutting, the trigger will be released and the motor will rotate in the reverse direction so that the object to be cut which is blocked can be disengaged from the blade teeth and the tool can be removed easily; meanwhile, thc motor is controlled to stop when the blade teeth of the movable blade and the fixed blade are superposed; and whenever the trigger is released, the blade teeth of the movable blade will hide inside of the blade teeth of the fixed blade (that is to say, the blade teeth are superposed), thereby avoiding the hurt resulting from the hands of people touching the sharp movable blade when leaving during the work or in the storage of the tool.

Brief Description of the Drawings

Fig. 1 is a schematic view showing the whole structure of a hedge trinmwr according to one emhcidimcntsiLthepresentinvention; Fig.2 is a schematic view showing a position in which the teeth of a movable blade and a fixed blade are superposed with each other according to the present invention; * Fig.3 is a schematic view showing a position in which the teeth of the movable blade and the fixed blade are not superposed with each other according to the present invention; Fig.4 is a schematic view of a Hall PCB board according to the present invention; Fig.5 is a schematic view of the induction position of the Hall element and a magnet; Fig.6 is a schematic view of the output level of the Hall element according to the present invention; Fig.7 is a circuit diagram of a motor control circuit according to the present invention; and Fig.8 is a flow diagram showing a control process of a control system for the blade teeth superposition of the cutting tool according to the present invention.

Detailed Description of the Preferred Embodiments

Next, the present invention will be further explained with reference to the drawings, taking a hedge trimmer for example.

The hedge trimmer of the present invention comprises a housing 1 having a motor 2 therein. The motor 2 controls the motion of a movable blade 7 by a transmission mechanism so that the movable blade 7 can move relative to a fixed blade 6 to cut the branches. The specific structures of the transmission mechanism, the movable blade 7 and the fixed blade 6 are not the significant contents of the present invention, and they may be configured as the prior structure forms and are not depicted in details here.

The present invention provides a control system for the blade teeth superposition of the hedge trimmer, wherein a Hall PCB board S is arranged adjacent to the movable blade 7 in the housing.

The Hall PCB board 5 is provided with a Hall element 3. A magnet 4 is provided at the head end of the movable blade 7, namely, at thc end adjacent to the motor. At one point of the motion track of the magnet 4, the projection of the magnet 4 on the Hall PCB coincides with the Hall element, thaUs_to-sa-yr-when-themovableblade-7-bHngsthemagnet-to-rotateracertain_po sition-of-the magnet 4 coincides with the position of the Hall element so that the Hall element and the magnet 4 are mutually-induced, and an induced leveL is outputted. When the projection of the magnet on the Hall PCB coincides with the Hall element, the teeth of the movable blade and the fixed blade are superposed with each other, and the Hall element is connected to the motor control circuit.

Preferably, one or more Hall elements are provided.

The motor control circuit comprises a MCU to which the Hall element is connected. The MCU is connected to the motor by a first drive module, a second drive module, a third drive module and a fourth drive module respectively. The first drive module, the second drive module, the third drive module and the fourth drive are connected to the motor by a transistor QI, a transistor Q2, a transistor Q3 and a transistor Q4 respectively. The transistor Ql and the transistor Q2 are connected to the positive pole of the power supply simultaneously, and the transistor Q3 and the transistor Q4 are connected to a RC circuit simultaneously and then connected to the ground. The MCU is connected to a battery voltage detecting circuit, a battery current detecting circuit, and a current detecting circuit simultancously.

In the circuit control system, the transistors Ql, Q2, Q3 and Q4 constitute an H bridge. The motor is connected between the H bridge. The four transistors equal to electrical switches without a contact in the system, and the MCU controls the drive circuits 1-4 to achieve the working status (on or oft) of the transistors.

Rc is a power resistance for detecting the discharging cuirent. A voltage can be generated when the discharging current flows through the resistance. The voltage will be detected by the current detecting circuit and a voltage signal will be transferred to the MCU to be processed.

The control method for the control system for the blade teeth superposition of the cutting tool according to the present invention comprises the following steps: Step-ldetecting-whether-the-current-the-voitage-and-the-temperature-exceed -the-linrit3-entering-------------Step 2 if the current, the voltage and the temperature of the battery do not exceed the limit; and sending an alarm message, stopping the output of the positive rotation of the motor, entering the reverse rotation status, and entering Step 3 if one or more of the current, the voltage and the temperature of the battery exceed the limit.

Step 2: the MCU in the motor control circuit detecting whether a major switch or a subsidiary switch is released at any moment in the process of the cutting tool rotating in the positive direction; Step 3: the MCTJ controlling the cutting tool to stop from the positive rotation status-immediately and enter into the reverse rotation status if it is detected that either of the major switch and the subsidiary switch is released; Step 4: in the period of the reverse rotation status, the MCU (microprocessor control unit) detecting the position of the blades by the Hall element and the magnet on the movable blade, as a low level is outputted by the Hall element when the blade teeth of the two blades are superposed and a high level is outputted by the Hall element when the blade teeth of the two blades are not superposed, and if the blade teeth of the two blades are superposed, the MCU will control the cutting tool to stop from the reverse rotation status, thereby performing a thnction of blade teeth superposition.

If either of the major switch and the subsidiary switch is released in the step of detecting whether the current, the voltage and the temperature of the battery exceed the limit, control the tool in accordance with Step 3) and Step 4).

With the control system for the blade teeth of the hedge trimmer according to the present invention, when the blade is blocked, it needs to release either or both trigger switches to allow the motor to rotate in the reverse direction, and the reverse rotation of the motor needs the release otthe4rigger-as-an-input4ignaLAt-themomentrthe4woi, lacles-in-the-forimof1he4ouble-motion blade or the movable blade in the form of the single motion blade move in the direction opposite to the original direction, so that the branch blocked in the blade teeth may released automatically, thus the object to be cut may be removed easily. Meanwhile, release the trigger at any moment, the blade teeth of the movable blade can mate with the blade teeth of the fixed blade, thereby avoiding the hurt resulting from the hands of people touching the sharp movable blade when leaving during the work or in the storage of the tool.

The above preferred embodiments disclose the present invention, but are not intended to restrict the present invention. The technical solutions obtained by equivalent replacement or transformation are considered as falling within the protection scope of the present invention.

Claims

<claim-text>WHAT IS CLAIMED IS: 1. A control system for the blade teeth superposition of a cutting tool, comprising: a housing and double blades, and at least one switch, wherein a motor control circuit and a blade position detecting device are arranged in the housing, the motor control circuit detecting the position of the blades by the blade position detecting device and control the double blades to stop on a teeth superposed position when the at least one switch is off
2. The control system for the blade teeth superposition of a cutting tool according to cairn 1,</claim-text> <claim-text>-the tool and a magnet provided on the blade.</claim-text> <claim-text>3. The control system for the blade teeth superposition of a cutting tool according to Claim I or 2, wherein the motor control circuit comprises a MCU which the Hall element is connected to, the MCTJ being connected to the motor by each drive module.</claim-text> <claim-text>4. The control system for the blade teeth superposition of a cutting tool according to Claim 1 or 2, wherein each drive module is connected to the motor by a transistor.</claim-text> <claim-text>5. The control system for the blade teeth superposition of a cutting tool according to Claim I or 2, wherein the MCIJ is connected to a battery voltage detecting circuit, a battery current detecting circuit, and a current detecting circuit simultaneously.</claim-text> <claim-text>6. A control method for thc control system for the blade teeth superposition of a cutting tool according to Claim 1, wherein it comprises the following steps: I) the MCU in the motor control circuit detecting whether a major switch or a subsidiary switch is released at any moment in the process of the cuffing tool rotating in the positive direction; 2) the MCU controlling the cutting tool to stop from a positive rotation status immediately and enter into a reverse rotation status if it is detected that either of the major switch and the subsidiary switch is released; 3) the MCU detecting the position of a first blade by the Hall element and the magnet on the first blade in the period of the reverse rotation status, and controlling the cutting tool to stop from the reverse rotation status if the blade teeth of the two blades are superposed so that a blade teeth superposition is achieved.</claim-text> <claim-text>7. The control method for the control system for the blade teeth superposition of a cutting tool according to Claim 6, wherein in Step 3), a low level is outputted by the Hall element when the -biade-teeth-of-the-two-blades-are-superposed--and-a-high-level-is-outputt ed-by-the-fiaii--element when the blade teeth of the two blades are not superposed.</claim-text> <claim-text>8. The control method for the control system for the blade teeth superposition of a cutting tool according to Claim 6, wherein it further comprises, before Step 1), the step of detecting whether the current, the voltage and the temperature of the battery exceed the limit, and entering Step 1) if the current, the voltage and the temperature of the battery do not exceed the limit, or sending an alarm message, stopping the output of the positive rotation of the motor, entering the reverse rotation status, and repeating Step 3) if one or more of the current, the voltage and the temperature of the battery exceed the limit.</claim-text> <claim-text>9. The control method for the control system for the blade teeth superposition of a cutting tool according to Claim 8, wherein the cutting tool is controlled in accordance with the step 2) and the step 3) if either of the major switch and the subsidiary switch is released in the step of detecting whether the current, the voltage and the temperature of the battery exceed the limit.</claim-text>