Snow blower

Abstract

To provide a snow blower for solving the problem that a deadman control, which is a standard safety device for the small walking-type snow blower, is intentionally disabled (deadman invalidation) by a user when the user becomes an obstacle to work from the beginning.SOLUTION: Load or pressure-sensitive detection means is provided between a handle and a deadman lever, and a control unit detects a fluctuation state of a grip load between the handle and the deadman lever during maneuvering, and the control unit determines if a deadman safety device has been disabled, issues a warning alarm, cuts off power, and makes an emergency stop.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention mainly relates to an improvement in the working safety of a rotary small snow blower, which is used mainly in small walk-behind snow blowers for personal use, farmers, stores, offices, small and medium-sized enterprises, etc. It shovels and collects the snow piled up by the auger, discharges it by a blower, and throws the snow to the place intended by the operator by a shooter.

Background Art

[0002] Small walk-behind snow blowers are widely used today for the above-mentioned individual retail use in snowy regions, separate from the large snow blowers used on public roads and public facilities managed by the state and prefectures. The snow removal work by this snow blower was conventionally the job of adult men, but with the passage of time and the declining birthrate and aging population, there has been a shortage of workers, and even the elderly and women are starting to do it. Currently, with various people using it, various safety devices for accident prevention are installed. Among them, the latest safety device is the dead man clutch. It is a technology that stops the power to the drive device when the operator leaves the snow blower during operation (forgetting to stop and leaving, temporarily leaving, falling, etc.), preventing the snow blower from running wild and preventing accidents. It was established as a safety standard in 2015 after the technological development efforts of each manufacturing company. This application is a new technology that further develops this safety device, prevents accidents beforehand, and enables anyone to perform snow removal work more safely.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The dead man clutch was devised due to the danger of the operator leaving the operating position. In small machines that do not require complex and advanced operations for driving, it has been put into practical use as a traveling clutch handle lever and a snow removal operation clutch handle lever, and has already been standardized in ISO8437 and ANSI-B71. On the other hand, even in medium and large-sized machines that require a more complex operating mechanism than that of small machines, there was a technical breakthrough, and it was formulated as the "Safety Standards for Walk-behind Snow Blowers" later than small machines (Non-Patent Document 1). Currently, as dead man (clutch) control by a dead man switch, the control mechanism is almost mature (Patent Document 1). Various methods other than switches have been tried (Patent Document 2), but they lack the certainty of safety control and have not yet been put into practical use. However, there has been a problem with this dead man control, which is supposed to be a safety device, that has made the manufacturing side and the safety management side think "unbelievable" from the beginning. That is, the user deliberately invalidates this safety device (i.e., dead man invalidation tampering). The most common is to tie the handle lever (the loop lever for medium and large-sized machines) to the handle with a string or the like, or clamp it with a vice or the like (Figs. 4, 6, 7) to keep the dead man switch in the ON state at all times, and use it in a dangerous state where continuous operation is possible even when the operator leaves. Accidents caused by this factor have not stopped, and it has become a social problem recently (Non-Patent Document 2). As a manufacturer that has been dealing with snow removal machines for many years, in order to address this situation, the present invention reexamined the completed dead man control to prevent users from disabling it. It reads the operation pattern from the on-off pattern of the dead man switch, determines whether the user has disabled the dead man function through tampering, and completed an AI dead man (Patent Document 3) to prevent such tampering. This application further evolves this technology.

Means for Solving the Problem

[0006] The means adopted in the present invention to solve the above problems is a small walk-behind snow removal machine composed of an auger that is a snow removal working part for mounting a prime mover, removing and collecting snow, a blower for discharging snow, and a shooter for determining the snow throwing direction. It is equipped with a dead man safety device for detecting the presence of the operator, and in a snow removal machine that operates by gripping the dead man lever together with the handle from above the handle, a load or pressure sensing means is provided between the handle and the dead man lever. The control unit detects the variation in the gripping load between the handle and the dead man lever during operation, and the control unit determines whether the dead man lever is tied to the handle or fixed with a vise, and whether there is any tampering to disable the dead man safety device. If so, it issues a warning alarm, cuts off the power, or performs an emergency stop.

Advantages of the Invention

[0007] By implementing the above means, the present invention has the following effects.

[0008] Regarding the tampering of the dead man lever, which accounts for most of the dead man disabling tampering, it can be almost perfectly discriminated, so accidents caused by disabling can be almost completely prevented.

[0009] False alarms and power cut-offs due to misjudgment can be almost completely eliminated, which can reduce the likelihood of users attempting to disable the dead man function through tampering, thereby enhancing safety.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Best Mode for Carrying Out the Invention

[0011] The basis of the detection and determination method of the dead man disabling modification of the present application is not to measure the numerical values of the gripping loads of the dead man lever and the handle, but to capture the state of the variation of the gripping loads. The linearity and reproducibility, which are the basic performances of the sensor, are not necessary, and a method with the highest possible sensitivity (for example, a piezo element) is suitable.

Example 1

[0012] Embodiments of the present invention will be described with reference to the accompanying drawings. Fig. 1 shows a front view of the snow remover of the present application, and Fig. 2 shows a view seen from the operator's side and the power transmission mechanism. The snow remover usually scrapes or cuts the accumulated snow with the auger 11, which is a rotating blade of the snow removal unit 1, collects it in the central part, takes it in, and discharges it at the peripheral speed of the blower with the blower 12 at the back of the central part of the auger 11, and throws the snow to the place intended by the operator by the shooter 2. The shooter 2 is operated by the shooter lever 45 on the operation panel 4 to control the left and right directions of snow throwing and the distance of snow throwing, respectively. Similarly, the snow removal unit 1 is also operated by the snow removal unit auger lever 44 to control the lift position and the left and right rolling positions. Since it is necessary to travel on snow, a configuration using crawlers 3 is generally adopted.

[0013] In the power transmission mechanism diagram, the running tension pulley 1TP controls the power input and cut-off of the crawler 3, and the blower-auger tension pulley 2TP controls the power input and cut-off of the blower 12 and the auger 11, performing normal operation control and dead man control. Each tension pulley is operated by a motor-driven wire (not shown in the figure) in the case of medium and large-sized machines. This series of controls is performed by the control unit 5 (Fig. 1) installed inside the operation panel 4. It is no exaggeration to say that this is a replacement for the previous manual clutch with a rod lever for medium and large-sized machines, and has been developed for dead man control and electrified in the industry. There are also some that use electromagnetic clutches, but they are extremely few.

[0014] Figure 3 shows the implementation status of the dead man's switch in the figure above and shows the relationship with the operation in Figure 2. As the snow removal operation procedure, first, when the steering wheel 41 and the steering lever 42 are held together, the dead man's handle switch DSW1 turns on, and the control unit 5 receives the signal, the travel clutch engages, and the auger switch OSW becomes ready to be turned on. The switch is also a travel clutch switch. After pressing this switch to engage the snow removal clutch and drive the snow removal unit 1, in order to operate the travel speed with the HST lever 43, the up and down and rolling posture of the snow removal unit 1 with the auger lever 44, and the snow throwing position with the shooter lever 45 almost in parallel, a certain degree of proficiency through practice is required. Among these, the dead man HST switch DSW2 is incorporated in the grip part of the HST lever 43, and the dead man auger switch DSW3 is incorporated in the grip part of the auger lever 44. During operation, since it is operated by pressing down from above with snow gloves or snow mittens, etc., the switch turns on during operation.

[0015] These switches also double as a travel clutch switch like the dead man's handle switch DSW1. Since it is necessary to constantly control the snow removal load during snow removal work, the posture of gripping the HST lever 43 for adjusting the travel speed and the up and down of the snow removal unit 1 and the auger lever 44 for adjusting the rolling posture increases. Beginners, the elderly, women, etc. often hold the steering wheel for stable operation, but some experienced users skip the steering lever and immediately grip these switches, turn on the travel clutch, and start snow removal work.

[0016] When any of the above three dead man switches is in the ON state, the operating snow remover is considered to be under the operation of the operator and continues to operate. However, when all of them are turned OFF, it is considered that the operator has left the stationed position due to some abnormality (such as falling or losing consciousness), and the power supply to the traveling and snow removal parts is cut off. This is a safety device named dead man control. In current medium and large-sized snow removers, this three-switch configuration has become the standard. However, considering the interruption time of the lever replacement during the operation, it does not immediately cut off the power when the switch is turned OFF. Instead, a normal slight delay time (about 1 second) is set. At the initial stage of development, there were also some designs that incorporated a dead man switch into the shooter lever 45. However, since the operation frequency is extremely low compared to the other two levers, it is rarely seen now. Besides the method of incorporating a switch into this operation lever, various methods of detecting the presence of the operator have been tried, but none of them have reached practical use.

[0017] The safety standard for snow removers started with the power cut-off method by disengaging this clutch. However, as it became more popular, there were cases where users disabled the dead man control of the snow remover because they thought it was in the way of their work, and it gradually spread. This was a very big shock to the industry because it was completely unexpected. Looking back, it is quite natural because it was a simple switch method, and it was easy to disable. Most of the disabling work was done with the dead man lever, which is easy to disable (Figs. 4, 6, and 7). Then, as snow remover accidents in snowy regions became a social problem (Non-Patent Document 2), the applicant of this application decided to work on measures to prevent the dead man from being disabled and completed the first method (Patent Document 3). However, at that time, as a concept, "execute when in doubt" was considered somewhat inevitable. That is, even if it was detected that the disabling work was done, an alarm was issued, and the safety control of disengaging the clutch was performed, but it turned out to be a mistake (even if it was a false alarm), it was considered somewhat inevitable.

[0018] In the middle part of FIG. 3, a deadman handle sensor DS1 for detecting the disabling trick of the present application is mounted between the loop handle 41 and the deadman loop handle lever 42, showing a state of detecting the grip operation loads of the lever and the handle of the operator. The piezoresistive elements are assembled into a flat sheet shape and are resistively connected by a control unit 5 in the control panel 4 at the wiring destination and converted into a bridge voltage. In the lower part of FIG. 3, the load (pressure)-resistance value characteristics and the bridge voltage characteristics of the piezoresistive elements are shown. Although the input-output characteristics are hardly describable as a sensor, only the sensitivity is high, being about two digits higher than that of conventional strain gauge type load sensors for measurement. This focuses on the piezo-type pressure sensor that has been growing rapidly in recent years due to the visualization of human senses, the tactile sensation of hands and fingertips, the texture feeling of clothes, robot operations (robot hands), etc., and the evolution of VR devices (VR gloves, VR suits, etc.). It can detect even a load of several grams and can be said to be in a different field from conventional load sensors.

[0019] FIG. 4 shows the state of the sensor output when snow removal work is performed with the deadman handle sensor DS1 mounted. The upper figure shows the sensor output for 28 seconds when operating without the deadman disabling trick, and the lower figure shows the sensor output for 28 seconds when operating with the deadman disabling trick. The disabling trick at this time was easily performed with large scissors, and a distinct difference appeared. In the middle graph, the pulsating waveform is the output waveform without the disabling trick, and the waveform close to a straight line including noise is the output waveform with the disabling trick. This can clearly distinguish the presence or absence of the disabling trick. Moreover, in the case of absence, although not intended, it seems that the state of the operator's operation can be imaginarily grasped as if in hand (→VR).

[0020] As described above, the operation of the operator's deadman lever 42 is observed by the control unit 5, and it is clearly determined whether there is no deadman disabling trick or there is a trick. If there is a deadman disabling trick, first an alarm is issued, and if the disabling trick is still not released, the power is cut off. The discrimination is made by observing the sensor output continuously three times every about 7 seconds, and using the network (parameters) of the handle operation dynamic patterns with and without the disabling trick that has been learned in advance in the control unit 5 to perform an AI determination on whether it is a control operation without the disabling trick. An adaptive Kalman filter is used for observing the output voltage waveform, and several dynamic patterns with and without the disabling trick of the handle operation are made into a network that has been learned in advance.

[0021] Looking at the sensor output voltage waveform in the first method confirmation test, it was initially thought that the initial AI determination development could be stopped and the determination could be made by simple threshold detection of the variation width. However, in subsequent various situation tests, it was found that there are more sensor output variation factors than expected, such as differences in the methods of disabling tricks (tying, fixing with a vice or pliers, etc.), differences among people, differences in the sizes of snow blowers (small, medium, large), and differences in the snow removal work environment. From the output waveform data of the deadman handle sensor DS1 with and without the disabling trick for several typical ones due to differences in control conditions as before, after Kalman filter processing, a network of the learned control dynamic patterns was created, and based on this, an AI determination method that can make a more reliable determination was developed.

[0022] It is determined whether the dead man safety device is disabled approximately 20 seconds (7 seconds × 3) after the start of the snow removal operation as described above, and a protection operation is performed. In the previous application (Patent Document 3), the operation pattern of the operator was learned from the ON-OFF pattern of the dead man switch during operation, and then it entered the AI determination, so the determination took more than 5 minutes. However, with this method, detection and determination can be performed almost simultaneously with the start of operation. Also, in the recognition of the operation pattern from the ON-OFF of the switch, doubts due to expectations cannot be completely eliminated. However, with this method, since the hand load of the operator is directly observed, the reliability is extremely high. It can be said that with this method, the probability of the determination of dead man disabling tampering being a false alarm can be made almost zero. The safety control for preventing dead man disabling tampering is different from other safety controls and is preventive safety. Just because tampering has occurred does not necessarily mean an accident will occur immediately. Since it is originally a control that disengages the clutch and shuts off the power against the will of the operator, even though it is called a safety device, it is a function that impairs usability, and it is desirable to avoid false alarms as much as possible.

[0023] Fig. 6 shows an embodiment for a small-sized machine. The dead man device of the small-sized machine is shown in the upper figure. After key start, the dead man travel lever 42ma is rotated and tilted to engage the travel clutch, and the vehicle can continue to travel with the crawler 3 by continuously holding the steering wheel 41m. When the hand is released from the steering wheel, the dead man travel lever 42ma returns to its original rotation position by springback, the travel clutch is disengaged, and the vehicle stops. The snow removal unit 1 also has a similar clutch mechanism with the dead man snow removal lever 42mb and the steering wheel 41m. In the case of a small-sized machine, dead man disabling tampering is performed by tying or clamping this lever (middle figure).

[0024] The lower part of Fig. 6 shows an embodiment. Similar to the case of the loop handle and loop handle lever of medium and large-sized machines, a dead man handle sensor DS1 is installed on the handle side between the handle 41m and the dead man driving lever 42ma. When detected and judged by a control unit (not shown) inside the wiring destination machine body, an alarm is issued and the engine is stopped several seconds later. Since the clutch of small-sized machines is manual rather than electric, the engine is finally stopped. In Europe and the United States, which are ahead in dead man safety standards, almost all small-sized machines are for small lots, and medium and large-sized machines are almost non-existent. By installing this device in export machines, Japan will now lead in safety measures.

[0025] The above is the new dead man disabling fraud prevention technology of the present invention. Doubts about the predictive control of the prior application (Patent Document 3) have been dispelled, and it has become a safety device that fully considers the usability of users. Based on the awareness that safety devices and workability are always in a trade-off relationship, in order to minimize malfunctions (idle operation) as much as possible, the control pattern has been thoroughly investigated from all angles. As a result, it has become a safety device that causes no discomfort to new users and can be recognized by old-generation users before the dead man in a relatively short time. As the applicant who has been engaged in snow removal machines since early on to contribute to the snowy regions, it is heartbreaking to see the news of snow removal machine accidents every winter despite the installation of safety devices in recent years. It is hoped that snow removal machine accidents will finally disappear with the market introduction of the present invention.

Industrial Applicability

[0026] It can be used in all walking work machines equipped with lever-type dead man safety control, such as agricultural machines and construction machines.

Explanation of Signs

[0027] 1 Snow removal part 2 Shooter 3 Crawler 4 Control panel 5 Control unit 11 Auger 12 Blower 31 HST 32 Travel mission 41 Loop handle (handle for medium and large models) 42 Dead man loop handle lever (dead man handle lever for medium and large models) 43 HST lever (travel speed operation lever) 44 Auger lever (snow removal unit attitude adjustment lever) 45 Shooter lever (snow throwing position adjustment lever) 46 Side clutch lever (travel left - right turning adjustment lever) 41m Handle (handle for small models) 42ma Dead man travel lever (also serves as travel clutch lever) 42mb Dead man snow removal lever (also serves as snow removal clutch lever) DS1 Dead man handle sensor (also serves as travel clutch switch) DSW1 Dead man handle switch (also serves as travel clutch switch) DSW2 Dead man HST switch (also serves as travel clutch switch) DSW3 Dead man auger switch (also serves as travel clutch switch) OSW Snow removal clutch switch (auger switch) 1TP Travel tension pulley 2TP Blower - auger tension pulley

Claims

Claim 1 A small walk-behind snow remover comprising an auger that is equipped with a prime mover and removes and collects snow, a blower that discharges snow, and a shooter that determines the snow-throwing direction, and having a dead man safety device for detecting the presence of an operator. In a snow remover of a type in which the dead man lever is grasped together with the handle from above the handle for operation, a load or pressure detection means is provided between the handle and the dead man lever, and the control unit detects the variation in the gripping load between the handle and the dead man lever during operation, and the control unit determines whether the dead man safety device has been disabled by tying the dead man lever to the handle or fixing it with pliers or scissors, and issues a warning alarm, or shuts off the power, or makes an emergency stop, and is equipped with a function for preventing tampering with the dead man disabling mechanism of a small walk-behind snow remover. Claim 2 The snow remover according to claim 1, wherein the load or pressure detection means is a sheet-shaped piezo-resistive "load-resistance value" conversion element mounted between the handle and the dead man lever and voltage-signal-converted by a control unit at the wiring destination, and is a sheet-shaped load sensor or pressure sensor.

Images