CN110621445A

CN110621445A - Predictive testing of power hand tools

Info

Publication number: CN110621445A
Application number: CN201880033442.2A
Authority: CN
Inventors: A.乌尔里希
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-03-21
Filing date: 2018-03-09
Publication date: 2019-12-27
Also published as: WO2018172105A1; EP3600781A1; EP3600781B1; DE102017204646A1

Abstract

The invention relates to a method for testing an electric hand tool, comprising the following steps: detecting a load of the power hand tool; determining a probability of failure of the power hand tool based on the load; and outputting a prompt if the probability of failure exceeds a predetermined threshold.

Description

Predictive testing of power hand tools

Technical Field

The present invention relates to an electric hand tool. More particularly, the present invention relates to techniques for determining the operational performance of a power hand tool.

Background

A power hand tool, for example a power screwdriver or a drill, is provided for performing mechanical tasks using electrical energy. In this case, the hand tool is subjected to wear in relation to its load. Generally, the longer the load lasts and the stronger the load, the greater the wear. However, it is not possible in a simple manner to determine when the wear is so great that the hand-held tool is no longer effective. The average running time or the age of the hand tool has not proven to be a reliable parameter.

Prompters are used on some power tools to notify or report a failure or impending failure of a component. For example, the carbon brushes of the electric motor may have wear contacts that may illuminate the LEDs when the carbon brushes are worn.

DE 102013016068 a1 proposes that the status data of a tool be known and output on the tool.

Various further solutions relate to the prediction of the failure of an element.

Disclosure of Invention

The object on which the invention is based is to provide an improved technique for testing a power hand tool. The invention solves this object by means of the subject matter of the independent claims. The dependent claims reflect preferred embodiments.

The method for testing an electric hand tool comprises the following steps: detecting a load of the power hand tool; determining a probability of failure of the power hand tool based on the load; and if the probability of failure exceeds a predetermined threshold, a prompt is output.

A user of the hand held tool may be alerted ahead of time to an impending failure of the hand held tool. Maintenance or servicing measures can be started in advance, thereby improving the usability of the hand-held tool. Different thresholds may be preset for different purposes. The threshold value may be selected to be smaller if the hand-held tool is used in a rescue service, for example, than if the hand-held tool is determined for use by a repairman.

It is particularly preferred to determine the probability of failure with respect to a predetermined statistical availability. Usability may dictate what power the power hand tool generates. The availability may include, for example, mechanical power. When the probability of availability less than 80% exceeds 95%, a prompt may be output, for example. The usual wear processes of a hand tool can be depicted in an improved manner by taking into account the availability.

In particular, different availabilities can be predetermined and different prompts can be output when the availability of an attachment with the determined probability of failure is no longer satisfied. For example, advance notices, warnings and reminders may be issued in sequence that the handheld tool should be serviced.

In a further preferred embodiment, a fault probability of an element of the electric hand tool is determined, and the fault probability of the electric hand tool is determined on the basis of the determined fault probability. The element may in particular comprise a structural component or a structural element. In a further embodiment, the failure probabilities of a plurality of elements can also be seen and correlated.

In this way, an advice that maintenance or repair intervention is required may be provided to a user of the hand-held tool based on the probability of failure of one or more elements. The probability of unexpected failures can thus be significantly reduced. The maintenance cost can be reduced. In particular, collateral damage, which can lead to additional costs, can be prevented by using a hand-held tool that is already partially worn or damaged. In particular, damage on parts which are not directly visible or damage caused by invisible wear (e.g. crack formation) can therefore be taken into account.

It is particularly preferred to receive a plurality of load information. In this case, a probability of at least one specific damage of the hand-held tool can be determined and a probability of failure of the hand-held tool can be determined on the basis of this probability.

In various preferred embodiments, for example, irreversible demagnetization of the motor, breaking of obstacles, bending or breaking of the switching disk in the tool lock, wear of the pressed-in pinion, excessive clutch torques, wear of the contact holder, discharge of the battery in the communication module, failure of the sensor, failure of an aged or defective energy accumulator or failure in the overall system of the electric hand tool can be taken into account.

It is particularly preferred that the load and function information of the electric hand tool is transmitted to a central unit, wherein the probability of failure of the electric hand tool is determined on the basis of the load and function information of a plurality of similar electric tools.

In other words, as much as possible different load information should be received at the power hand tool and a malfunction of an element of the hand tool detected. This detection is performed by as large a number of similar hand-held tools as possible. This makes it possible to increase the statistical population on the basis of which the probability of failure of the individual power tools can be reliably determined. In particular, the relationship between a particular form of load and a fault in an element of the power hand tool can be modeled in an improved manner.

The computer program product comprises program code means for performing the above-mentioned method when the computer program product is run on a processing device or stored on a computer readable data carrier.

The control device for a power hand tool comprises a sampling means for detecting the load of the power hand tool; processing means for determining a probability of failure of the power hand tool based on the load; and output means for outputting a prompt in the event that the probability of failure exceeds a predetermined threshold.

The control device can be provided in particular for carrying out the above-described method partially or completely. The processing means may in particular comprise a programmable microcomputer, and the method described above may be in the form of a computer program product for implementation on the processing means. The features and advantages of the method may thus also be applied to the control device and vice versa.

It is particularly preferred that the control device has a communication device for coupling to a further instrument. The further instrument may in particular comprise a central mechanism as described above. Part of the determination of the failure probability may be performed at the central authority.

In another embodiment, the further apparatus comprises, for example, a mobile telephone, a portable or stationary computer. Additional instruments may be provided for connection to the central mechanism. In one embodiment, the prompt is output on another instrument. For this purpose, a part of the method described above, in particular the determination of the failure probability, can be carried out on the part of the further instrument.

The central facility is provided for receiving load and function information of a plurality of mutually similar electric hand tools and determining a fault probability of the electric hand tool based on the received information and load of the electric hand tool.

Drawings

The invention will now be described in more detail with reference to the accompanying drawings. Wherein:

FIG. 1 shows a schematic view of a power hand tool;

FIG. 2 illustrates a system having a power hand tool;

FIG. 3 shows a flow chart of a method for inspecting a power hand tool; and

fig. 4 shows a graph with probability of failure.

Detailed Description

Fig. 1 shows a schematic view of a power hand tool 100. The power hand tool 100 preferably comprises a hand-held tool and is electrically operable. In the embodiment shown, the power hand tool 100 comprises an electrical energy store 105, but in another embodiment a cable connection to an electrical supply network can also be provided. Purely exemplarily, the illustrated hand tool 100 is implemented as a hand-held power drill. Other possible power tools include, for example, electric screwdrivers, saws, lawn trimmer shears, hedge shears, flashlights or kitchen power tools such as electric blenders.

The hand tool 100 comprises in the embodiment shown an electric motor 110, which acts on a drill sleeve 120 via a transmission 115. A drill bit or chisel may be clamped into the bit housing 120. The transmission 115 may include a clutch or a hammering mechanism. In one embodiment, the invention relates to a manual transmission having a plurality of shiftable gear stages. The control device 125 is provided for controlling the functions of the hand tool 100, in particular the current through the electric motor 110, according to user controls.

It is proposed that the load information and the function information of the individual elements 105 to 125 of the hand-held tool 100 are sampled and further processed. A dedicated control device can be provided for this purpose, or the control device 125 can assume this task. To this end, the control device 125 preferably comprises a processing means 130, which may comprise, in particular, a programmable microcomputer or microcontroller. Furthermore, the processing device 130 is connected to at least one sensor 135, which is provided to provide load information of the hand tool 100. The sensor 135 may include, among other things, a temperature sensor, an acceleration sensor, or a current sensor. For example, the operating time, the load cycle, the charging cycle, the power consumption, the load curve, the temperature curve or other suitable load data in the hand tool 100 can be detected by one or more sensors 135. The control device 125 is preferably arranged to store and/or further process or interpret the detected information.

It is particularly proposed that the control device 125 is provided for determining a probability of failure of a component, a component or the entire handheld tool 100 on the basis of load information and predetermined availability information of individual components of the handheld tool 100. In particular, statistical methods can be used here, which relate the specific load of the hand tool 100 to an empirically or otherwise detected correlation between the load and a fault of similar hand tools 100. In other words, the probability of failure of an element or the entire handheld tool 100 may be determined based on the detected load information by comparing how many other power handheld tools 100 remain sufficiently effective under similar loads. It is variable here as to what should be understood correctly as "sufficient effectiveness". For example, a reduction in the mechanical power available at the bit sleeve 120 occurring in a predetermined portion may indicate a need for maintenance of the hand-held tool 100 with a further predetermined probability. Furthermore, the probability of failure of the power hand tool 100 can be determined on the basis of the known loads to be borne by the elements of the hand tool 100 or the entire hand tool 100, for example in the form of statistical failure probabilities B1, B10, in median numbers or the like. In particular, a continuous, increasingly urgent warning can be output when the probability of failure exceeds a successively higher threshold or falls below a decreasing statistical availability.

The output device 140 may be configured to: the user is notified optically, acoustically and/or tactilely when the determined probability of failure exceeds a predetermined threshold under the selected conditions.

In another embodiment, the communication module 145 is configured to couple with an external instrument.

Fig. 2 shows a system 200 with a power hand tool 100. A plurality of hand-held tools 100, here illustratively drills and power screwdrivers, are exemplarily shown. The power hand tool 100 is wirelessly coupled with another instrument by means of the communication module 145. Further instruments may include, inter alia, instruments that are controllable by a user of the handheld tool 100, such as a mobile phone ("smartphone"), a portable computer ("tablet", "laptop") or a stationary computer ("desktop"). The communication between the hand-held tool 100 and the user computer 205 can be realized, inter alia, by means of WLAN, bluetooth, WiMAX, NFC or similar technology. The user computer 205 may be communicatively coupled to a central facility 210. The central entity 210 is preferably provided for detecting a large number of loads and functional information of the hand-held tool 100 and storing them in the data memory 215.

Based on the stored data, it can be determined, for example, with a given load information and with what probability a malfunction of the hand-held tool 100 is highlighted given a predetermined availability of the hand-held tool 100. Furthermore, for example, a malfunction of an element of the hand tool 100 can be predicted on the basis of the mentioned information. In addition, specific damage to the hand-held tool 100 may be diagnosed or predicted based on the received information. The impact of damage on the probability of failure or usability of the hand-held tool 100 may be determined accordingly. This determination may be performed in various embodiments on the part of the central authority 210, on the part of the user computer 205, or on the part of the hand-held tool 100. In another embodiment, the handheld tool 100 is directly connected to the central facility 210 and the user computer 205 is eliminated. Regardless of the connection between the hand-held tool 100 and the central facility 210, the output of the determination result may also be implemented on the user computer 205. The output may include an optical, acoustic, or tactile cue.

Fig. 3 shows a flow chart of a method 300 for testing the power hand tool 100. The method 300 may be performed in various embodiments partially or entirely in connection with the hand-held tool 100, the user computer 205, or the central facility 210.

Information about the load of the hand tool 100 is detected in step 305. The detection may include sampling the information via the sensor 135 or storing operational parameters on the part of the control device 125. In step 310, a load versus time profile is optionally determined. In step 315, the probability of failure of the component or of the entire handheld tool 100 can be determined. Alternatively or additionally, a probability of the presence of a predetermined damage may be determined in step 320.

The damage may involve multiple elements of the hand held tool 100. For example, a predetermined degree of wear of the different elements may together produce a damaged image. Possible damage includes irreversible demagnetization of the electric motor 110. Here, the magnetic field strength of the permanent magnet of the electric motor 110 may be reduced. The available mechanical power at the bit housing 120 may thereby be reduced. Additional damage may include breaking of obstacles, bending or breaking of switch disks or other mechanical deformations or wear of components of the transmission 115 or bit holder 120. Such damage may be determined, for example, based on vibration information during use of the hand-held tool 100. Additional damage includes: wear of the pressed-in pinion, which can likewise be determined on the basis of the vibration information; or the clutch torque exceeds a predetermined threshold. To this end, the transmission 115 may comprise a clutch, and the torque transmitted by the clutch may be determined, for example, by means of a torque sensor 135.

Additional damage may occur when the battery of the communication module 145 is nearly discharged, or one of the sensors 135 fails. Aged or defective power storage 105 (whose capacity decreases based on aging or defect) may also be determined as a failure image. In further embodiments, it may be determined whether the overall system 100 has reached the end of the design useful life. The service life may be determined based on time or may take into account the load. If the hand-held tool 100 is subjected to frequent vibrations or accelerations, for example, when the user inaccurately or incorrectly operates the hand-held tool 100, the design service life may be reached more quickly than under a small load.

In step 325, a probability of failure of the handheld tool 100 may be determined. The probability of failure can be determined, in particular, on the basis of previously determined information and, further preferably, on the basis of statistical knowledge of a large number of similar hand-held tools 100.

If it is determined in step 330 that the probability of failure is above a predetermined threshold, then a corresponding prompt may be output in step 335. The prompts may be presented in different embodiments on the hand-held tool 100 or on the user computer 205.

As mentioned, it is particularly preferred to determine the fault probability on the basis of as much as possible statistical information of similar or structurally identical hand-held tools 100. The information detected in step 305 or 310 can thus be transmitted to the central authority 210 in step 340. In step 345, this information may be adjusted using information present at central facility 210. The adjustment result may be returned in step 350. In another embodiment, the selected information may also be transmitted from the central facility 210 to the handheld tool 100, and the handheld tool may use the received information itself to adjust the local information.

Fig. 4 shows a graph 400. The time until a mechanical failure occurs is provided in the horizontal direction and the failure probability is provided in the vertical direction. The information shown is considered exemplary for a given power hand tool 100. The time scale is divided anti-logarithmically and the probability scale is divided logarithmically. The two dimensions are exemplary respectively and are given for qualitative purposes only. Exemplary statistical characteristics include:

form (a): 5.18

Dimension: 86.58

The following aspect value: 79.66

Standard deviation: 17.67

Median: 80.67

IQR：24.15

And (4) failure: 5

Grading: 1

AD* ：9.19

Correlation: 0.94.

starting from the Weibull distribution of faults. At the first point 405, the B10 failure probability is within the 85% confidence interval for approximately 47 hours. The middle service life (median) is about 80 hours.

Claims

1. Method (300) for testing an electric hand tool (100), wherein the method (300) comprises the steps of:

-detecting (305) a load of the power hand tool (100);

-determining (325) a probability of failure of the power hand tool (100) based on the load; and is

-outputting (335) a prompt if the probability of failure exceeds a predetermined threshold.

2. The method (300) of claim 1, wherein a probability of failure is determined with respect to a predetermined statistical availability.

3. The method (300) according to claim 2, wherein the not-as-high availability is predetermined and different prompts are output when a failure probability of the respectively assigned availability is reached.

4. The method (300) according to any one of the preceding claims, wherein a probability of failure of an element of the power hand tool (100) is determined and the probability of failure of the power hand tool (100) is determined (325) based on the determined probability of failure.

5. The method (300) according to any of the preceding claims, wherein a plurality of load information is received, a failure probability of at least one specific damage of the hand-held tool (100) is determined (320), and a failure probability of the hand-held tool (100) is determined (325) based on the failure probability.

6. The method (300) according to any of the preceding claims, further comprising transmitting (340) load and function information of the power hand tool (100) to a central authority (210), wherein the probability of failure of the power hand tool (100) is determined based on load and function information of a large number of similar power tools (100).

7. Computer program product having program code means for performing the method (300) according to any one of the preceding claims, when the computer program product is run on a processing device (130) or stored on a computer-readable data carrier.

8. Control device (125) for an electric hand tool (100), comprising:

-a sampling device (135) for detecting a load of the power hand tool (100);

-processing means (130) arranged for determining a probability of failure of the power hand tool (100) based on the load; and

-output means (140) for outputting a prompt in case the probability of failure exceeds a predetermined threshold.

9. The control device (125) according to claim 8, further comprising wireless communication means (145) for coupling with a further instrument (205), wherein the prompt is output on the coupled instrument (205).

10. A central mechanism (210) arranged to receive load and functional information of a number of mutually similar power hand tools (100) and to determine a probability of failure of the power hand tool (100) based on the received information and load of the power hand tool.