JP7629635B2 - Snowfall sensor and snow melting device - Google Patents

Description

The present invention relates to a snowfall sensor that detects snowfall information and a snow melting device.

In regions where snowfall is common, snow melting devices are used to protect roads and sidewalks essential to daily life from snow damage. There is a demand for technology that uses snowfall sensors to detect snowfall and automatically operates the snow melting device when snowfall that causes snowfall occurs (see, for example, Patent Document 1).

JP 2005-213755 A

The snowfall sensors used to control such equipment have the advantages of being inexpensive, having high detection accuracy, and being unlikely to go undetected, and are designed to detect the air temperature using a temperature sensor, and to detect the number of snowflakes per certain period of time using a photoelectric sensor that emits infrared light, which has a longer wavelength than visible light and is less likely to scatter, and receives the light reflected by the snowflakes.

In snowfall sensors, a photoelectric sensor, which is an electronic device, is installed inside a sealed casing with a window to prevent it from being affected by rain and wind, and a structure is used in which snowflakes are detected through the window. If snow accumulates on the window and blocks it, snowflakes cannot be detected, so a heat retention heater is installed inside the casing of the snowfall sensor, and electricity is applied to the heater when the air temperature detected by the temperature sensor falls below a certain temperature, and electricity is stopped when the air temperature rises above the certain temperature.

Since the heat retention heater generates a high heat temperature, if it is installed in direct contact with the window or the casing part around the window, the window or casing part is likely to be thermally deformed. Therefore, by installing the heat retention heater inside the casing without touching the window or the casing part around the window, the space inside the casing is heated by the heat retention heater and the heater heat is transferred to the window or casing, preventing snow from accumulating on the window. To assist in the transfer of heat, a heat dissipation member is sometimes placed between the window or cover and the heater. However, a configuration in which the heat dissipation member is placed inside the cover increases the number of parts, which reduces productivity, and the cover becomes larger by the space for the heat dissipation member. This results in issues such as an increase in the area where snow accumulates and the associated need to increase the heat output of the heat retention heater.

The present invention aims to provide a snow sensor and snow melting device that can ensure high thermal insulation performance.

A snowfall sensor according to one embodiment of the present invention comprises a body, a cover having a light-transmitting window, a casing having a sensor unit provided within the cover and a partition plate, and a first heater provided within the cover below the sensor unit, wherein the partition plate divides the space of the casing into an upper first chamber and a lower second chamber, a substrate is arranged in the first chamber and the partition plate holds the substrate, which divides the first chamber into front and rear chambers, the first heater is provided within the cover, in a lower region or below the window, on the same side as the sensor unit with respect to the substrate, in the first chamber divided into front and rear chambers by the substrate, and the sensor unit and the first heater are disposed in the region between the substrate and the window.

The present invention makes it possible to provide a snow sensor and snow melting device that can ensure a high heating effect.

FIG. 1 is an explanatory diagram showing a configuration of a snow melting device according to a first embodiment of the present invention. FIG. 4 is a cross-sectional view showing the configuration of a snowfall sensor of the snow melting device. FIG. FIG. FIG. 2 is an explanatory diagram showing the circuit configuration of the snowfall sensor. FIG. 11 is a cross-sectional view showing the configuration of a snowfall sensor according to another embodiment of the present invention. FIG. 11 is a cross-sectional view showing the configuration of a snowfall sensor according to another embodiment of the present invention.

The snow melting device 100 and snow sensor 1 according to one embodiment of the present invention will be described below with reference to Figs. 1 to 5. Fig. 1 is an explanatory diagram of the snow melting device 100 according to the first embodiment. Fig. 2 is a cross-sectional view of the internal configuration of the snow sensor 1 as seen from the side, and Fig. 3 is a cross-sectional view of the internal configuration of the snow sensor 1 as seen from the front. Fig. 4 is a cross-sectional view of the internal configuration of the snow sensor 1 as seen from above. Fig. 5 is an explanatory diagram showing the circuit configuration of the snow sensor.

As shown in FIG. 1, the snow melting device 100 includes a snowfall sensor 1, a snow melting device 2, and a control device 3. The snow melting device 100 is a device that melts snow in a location to be melted, such as a road.

The snowfall sensor 1 comprises a casing 10, a control board 11, a first temperature sensor 12, a distance measuring sensor 13 as a sensor unit, multiple heaters 14A, 14B, multiple cables 15a, 15b, and a second temperature sensor 16. The snowfall sensor 1 is installed, for example, outdoors, detects snowfall information in a target area As, and sends an operation signal for the snow melting equipment 2 to the control device 3. The snowfall sensor 1 also receives power from the control device 3 that operates the snow melting equipment 2. The snowfall sensor 1 may further comprise a remote control 4 for remote operation.

The casing 10 comprises a body 17, a cover 18, and partition plates 19a and 19b.

The body 17 is cylindrical with openings at the top and bottom. An antenna mast is inserted into the opening at the bottom of the body 17 and is connected to the antenna mast. The body 17 forms a base for supporting the snow sensor 1 at the installation location. A first partition plate 19a is disposed in a circular opening 17a formed at the top end of the body 17. A second partition plate 19b is disposed midway in the axial direction of the body 17.

Cable holes 17c are formed in the body 17 at two locations above the position where the partition plate 19b is located, penetrating the peripheral wall. The cable holes 17c are circular through-holes into which the connection cables 15a and 15b are inserted.

The cover 18 is made of, for example, a synthetic resin material, and has a roof portion 18a and a flange portion 18b as an integral part. The cover 18 opens downward, and the upper end of the body 17 is inserted into the flange portion 18b, and the periphery is joined by being watertightly glued.

The roof portion 18a is made of, for example, a light-transmitting synthetic resin material and is configured in a hemispherical dome shape that opens to the bottom. The roof portion 18a has a rectangular window portion 18c in the center of the front portion. The window portion 18c is configured in a flat plate shape and is configured to allow light from the distance measuring sensor 13 to pass through. The window portion 18c is made of a light-transmitting material and is thinner than the surrounding areas of the roof portion 18a, for example, with a thickness of about 1 mm. The outer surface of the roof portion 18a has a curved shape that allows snow that falls from above to easily fall off without accumulating.

The inner wall of the roof portion 18a is formed with a protrusion 18e that forms an engagement surface that engages with the periphery of the control board.

The partition plates 19a and 19b are formed of, for example, a synthetic resin material or a rubber material, and have a circular plate-like outer shape. The partition plates 19a and 19b are arranged along a plane perpendicular to the axis of the body 17. As shown in FIG. 3, the upper partition plate 19a is provided at the connection between the cover 18 and the body 17, and covers the opening 17a at the upper end of the body 17. The partition plate 19a is formed, for example, in a circular shape, and has a slit extending radially in the center and through which the control board 11 passes. The partition plate 19a divides the space inside the casing 10 into an upper first chamber 20a and a lower second chamber 20b, and holds the control board 11, preventing the sensor and the control board 11 from falling. That is, the partition plate 19a divides the interior of the storage space formed by the roof portion 18a and the body 17 and accommodating the control board 11 in the vertical direction, and the partition plate 19a and the roof portion 18a form a first chamber 20a that accommodates the distance measurement sensor 13 and part of the control board 11. The first chamber 20a is also divided into front and rear by the control board 11.

Partition plate 19b is provided midway in the axial direction in the internal space of body 17. Partition plate 19b is disposed below partition plate 19a and control board 11. Partition plate 19b divides the space within body 17 into second chamber 20b, which houses control board 11, and third chamber 20c, which is formed below second chamber 20b. Partition plate 19b prevents raindrops from entering through a hole at the bottom end of body 17.

The control board 11 is a circuit board and is erected inside the casing 10. The control board 11 is arranged from the space inside the cover 18 to the space inside the body 17. The control board 11 is a plate-like member having a rectangular first base portion arranged inside the body 17 and a second base portion having an arc-shaped edge that follows the shape of the cover 18, which are continuous and integral with each other. A notch is formed at the boundary between the first base portion and the second base portion, which engages with and is supported by the outer edge of the partition plate 19a.

The control board 11 is equipped with various control devices such as a memory unit 21, a sensor control unit 25, a first temperature sensor 12, and a second temperature sensor 16.

The memory unit 21 includes, for example, a RAM and a ROM, and stores various set values and calculation formulas. For example, the memory unit 21 stores information such as the distance sent from the distance sensor 13 and the temperature sent from the temperature sensor 12 as snowfall information.

The first temperature sensor 12 is equipped with, for example, a temperature detection element, detects temperature information, and sends the detected signal to the sensor control unit 25. For example, the first temperature sensor 12 is provided on the cable 15b and detects the air temperature. The first temperature sensor 12 may also be mounted on the control board 11.

The second temperature sensor 16 is disposed in the location to be melted, for example, a road, and detects the ground temperature. The second temperature sensor 16 includes, for example, a temperature detection element and a sensor case. The second temperature sensor 16 detects temperature information of the road and sends the detected signal to the sensor control unit 25.

The distance measurement sensor 13 is, for example, a triangulation type photoelectric sensor. The distance measurement sensor 13 includes a sensor case 22, a light projecting unit 23 mounted on the sensor case 22, and a light receiving unit 24. The sensor case 22 of the distance measurement sensor 13 is screwed onto the control board 11 and positioned opposite the window portion 18c. The distance measurement sensor 13 is connected to a sensor control unit 25 provided on the control board 11.

For example, the distance sensor 13 measures the distance to a target (object) placed in a detection area that includes a long distance of up to about 1 m. For example, the detection area is set to an area within a certain distance from a cone-shaped irradiation area that spreads forward from the light projecting unit 23 and the light receiving unit 24.

The light projecting unit 23 has an emitter that emits invisible light in a cone shape. For example, the light projecting unit 23 emits pulsed infrared light as invisible light at regular intervals. The invisible light is, for example, near-infrared light in the invisible light range with a wavelength of 800-1200 nm, specifically, a wavelength of about 940 nm.

The light receiving unit 24 includes a detection element that receives the light reflected by the target. For example, the light receiving unit 24 includes a plurality of detection elements arranged in an array.

The first heater 14A and the second heater 14B are provided in the first chamber 20a, for example, in the lower region of the first chamber 20a. For example, in the first chamber 20a, the first heater 14A is arranged below the distance measurement sensor 13 and the window portion 18c, and the second heater 14B is arranged above the distance measurement sensor 13 and the window portion 18c. The heaters 14A and 14B are provided in the region between the control board 11 and the window portion 18c. The heaters 14A and 14B have a heating element that generates heat when a voltage is applied, and are operated and generate heat under the control of the sensor control unit 25 fixed to the control board 11. The heaters 14A and 14B prevent snow from accumulating on the window portion 18c due to heat generation. For example, the heaters 14A and 14B are heater devices of the same model. For example, multiple heaters 14A and 14B are connected in parallel.

The heaters 14A and 14B are arranged such that the output of the first heater arranged below is greater than the output of the second heater arranged above. The heaters 14A and 14B are arranged in the front space of the first chamber 20a, which is divided into front and rear by the control board 11, i.e., on the same side of the control board 11 as the distance measurement sensor 13. In this embodiment, the heaters 14A and 14B are arranged one above and one below, and the output of the first heater 14A arranged below is set to be greater than the output of the second heater 14B arranged above. That is, for example, if the output of the first heater is R2 and the output of the second heater is R1, then R2>R1. Therefore, the amount of heat dissipated by the first heater 14A is greater than the amount of heat dissipated by the second heater 14B.

The connection cables 15a and 15b include, for example, a power supply line and a signal line. One of the connection cables 15a passes through a cable hole 17c in the body 17, one end of which is connected to the control board 11 inside the housing, and the other end of which is led out of the housing and connected to the control device 3. The other connection cable 15b passes through a cable hole 17c, one end of which is connected to the control board 11 inside the housing, and the other end of which is led out of the housing. The other end of the connection cable 15b is connected to the second temperature sensor 16. The ends of the connection cables 15a and 15b that are arranged in the cable hole 17c are provided with a pipe member 15d that covers the outer surface.

The sensor control unit 25 includes, for example, a CPU, various processing circuits, and a conversion circuit. The sensor control unit 25 controls the operation of the snowfall sensor 1 and the snow melting device 2 according to information sent from the light receiving unit 24 and the temperature sensor 12 and various programs previously stored in the memory unit 21.

The sensor control unit 25 is connected to the distance measurement sensor 13, and emits infrared light from the light projecting unit 23 under predetermined conditions, and measures the distance to a target present in the target area based on the signal detected by the light receiving unit 24, thereby detecting the measurement information.

For example, the sensor control unit 25 detects snowfall information based on the detection results of the first temperature sensor 12, the distance measurement sensor 13, and the second temperature sensor 16. For example, the sensor control unit 25 calculates the number of snowflakes (snowflake count number) based on the number of times the distance to the target is detected in the target area As and the distance information. As an example, the sensor control unit 25 calculates the number of snowflakes by counting the number of times the distance measurement sensor 13 detects the distance to the target within a specified area as the number of snowflakes. The sensor control unit 25 detects signals from the temperature sensors 12, 16 and the distance measurement sensor 13, and judges the snowfall condition based on the temperatures detected by the temperature sensors 12, 16 and the information on the number of snowflakes per hour obtained from the signal from the distance measurement sensor 13, and sends an operation signal to the control device 3.

Then, based on the number of snowflakes and temperature information, the sensor control unit 25 operates the snow melting device 2 when the operating conditions of the snow melting device 2 are met, or sends an operation signal to the control device 3 to stop the snow melting device 2 when the stop conditions of the snow melting device 2 are met. For example, the sensor control unit 25 operates the snow melting device 2 when the number of snowflakes per certain time in the target area As exceeds a predetermined value, and sends a signal to the output board 35 of the control device 3 to stop the snow melting device 2 when the number of snowflakes per certain time in the target area As falls below a predetermined stop reference number. In addition, the sensor control unit 25 may stop the power supply to the distance measurement sensor 13 and turn off the operation signal to the control device 3 when the air temperature detected by the temperature sensor 12 rises above the stop reference temperature T2 (e.g., T1 + 0.5 ° C., 3.0 ° C.). The sensor control unit 25 may also control the drive of the distance measurement sensor 13 based on the temperature detected by the temperature sensors 12 and 16. For example, if the detected temperature is below a certain temperature, the distance measurement sensor 13 is activated and the light projector 23 of the distance measurement sensor 13 emits pulsed infrared light, and when the air temperature rises to a certain value, the emission is stopped.

The sensor control unit 25 also controls the operation of the heaters 14A and 14B based on the temperatures detected by the various temperature sensors 12. For example, the sensor control unit 25 acquires a signal from the temperature sensor 12, and based on the temperature information from the temperature sensor 12, drives the heater 14 when the operating conditions of the heater 14 are met, or stops the heater 14 when the stopping conditions of the heater 14 are met. As an example, when the air temperature detected by the temperature sensor 12 falls below a predetermined heater operation first temperature T3 (e.g., 3.0°C), it energizes the heater 14, and when the air temperature rises to a predetermined heater stop temperature T4 (e.g., 4.0°C), it stops energizing the heater 14.

For example, the sensor control unit 25 may adjust the output based on the temperature conditions, and may control the operation with, for example, multiple stages of output. That is, for example, when the air temperature becomes equal to or lower than the preset heater operation temperature T3, the voltage is applied to the heaters 14A and 14B for a preset time with a preset first output, for example, a duty of 50%, and when the air temperature becomes equal to or lower than the heater operation second temperature T5 set lower than the heater operation temperature T3, the voltage is applied with a second output higher than the first output, for example, a duty of 100%. Then, when the detected temperature rises by a predetermined temperature from or lower than the heater operation second temperature T5 and rises to or higher than the reference temperature T6 higher than the heater operation second temperature T5, the output is reduced, and the voltage is applied with, for example, the preset first output. As an example, the reference temperature T6 for reducing the output is set to a temperature lower than the heater stop temperature T4 and higher than the heater operation temperature T3 and the heater operation second temperature T5. Furthermore, when the air temperature rises by a predetermined temperature and reaches a predetermined heater stop temperature T4, the sensor control unit 25 stops applying voltage to the heaters 14A and 14B.

As shown in FIG. 1, the snow melting equipment 2 is installed at a location where snow is to be melted, for example, on a road. For example, in the case of a sprinkler type structure in which groundwater is pumped up and used as water for melting snow, the snow melting equipment 2 is equipped with a snow melting pump. The snow melting equipment 2 performs a sprinkling operation to melt the snow at the location to be melted, for example, on the road, in response to a signal output from the control device 3. The signal is, for example, a signal (ON signal) that directly starts the snow melting pump. The snow melting device 100 operates the snow melting equipment 2 in response to the signal, sends snow melting water to the pipes, and sprinkles it on the road, melting the snow on the road.

As a specific example, the control device 3 outputs a signal to control the snow melting device 2, and performs a water sprinkling operation to melt snow in a location to be melted, for example, on a road. The signal is a signal (ON signal) that directly starts a snow melting pump. The snow melting device 2 is operated by a signal output from the control device 3, and sends snow melting water to a pipe and sprinkles water on the road, melting the snow on the road.
The control device 3 includes a display unit 33, an operation unit 34, and an output board 35. The control device 3 is connected to the snow sensor 1 via a connection cable 15a so as to be able to supply power and transmit and receive signals. The control device 3 supplies power (power supply) to the snow sensor 1 via the connection cable 15a, and controls the operation of the snow melting device 2 according to an operation signal sent from the snow sensor 1. For example, the control device 3 is connected with three wires via the connection cable 15a: a DC power supply, an operation signal, and 0V.

The display unit 33 is a display that displays information such as temperature information and the number of snowflakes.
The operation unit 34 includes input devices such as a power switch and various operation buttons.

The output board 35 is, for example, a circuit board, and is equipped with various control devices. The output board 35 has, for example, an operation circuit that switches ON/OFF an operation relay that operates the snow melting equipment according to an operation signal from the snow sensor, and an opening/closing relay that opens and closes a solenoid valve according to an operation signal from the snow sensor, and a DC power supply unit that rectifies AC power and supplies DC to the snow sensor. The control device 3 operates the snow melting equipment 2 according to the operation signal from the snow sensor 1.

The snowfall sensor 1 device according to the above embodiment provides the following effects. That is, by providing a heater located below the first chamber 20a, which is the space that houses the distance measurement sensor 13, convection can be utilized, resulting in energy savings. Also, by providing a heater 14B above the distance measurement sensor 13, the space can be effectively heated and snow can be prevented from accumulating on the cover 18. Also, by providing heaters 14A and 14B in the same space as the distance measurement sensor 13, which is located opposite the window portion 18c, within the first chamber 20a, which is divided into multiple compartments, the window portion 18c can be effectively heated.

Furthermore, by increasing the output of the lower heater 14A, convection can be generated more effectively, resulting in significant energy savings.

In addition, by using the same model for multiple heaters 14A and 14B, it is possible to reduce the number of component types and prevent installation errors during production. Furthermore, if a heater breaks down or breaks, in the case of a series connection, the voltage application to all heaters may stop in the event of a break, but in the above embodiment, by connecting heaters in parallel, a constant voltage application can be assumed at all times, ensuring a constant heat retention effect.

The present invention is not limited to the above embodiment. For example, various setting values and calculation reference values can be changed as appropriate.

For example, in the above embodiment, one heater 14A and one heater 14B are provided at the bottom and the top, respectively, but this is not limited to this. For example, as another embodiment, as shown in FIG. 6, a snowfall sensor 1A may be used in which no heater is provided at the top, and only the first heater 14A is provided at the bottom. In this case, the heat of the heater 14A at the bottom rises, and effective heating of the space can be achieved. In addition, there may be multiple heaters 14A and/or 14B. For example, as another embodiment, a snowfall sensor 1B shown in FIG. 7 is configured to have two first heaters 14A and one second heater 14B. In these cases, the heat of the heater 14A at the bottom rises, and convection occurs in the first chamber 20a in the cover 18, and the window portion 18c can be effectively heated.

For example, as shown in FIG. 7, when the number of heaters 14A is greater than the number of heaters 14B, heaters 14A and 14B can be connected in parallel and driven with the same output, resulting in the output of the lower heater 14A being greater than the output of the upper heater 14B, making it possible to effectively utilize convection.

In the above embodiment, an example was shown in which the output of the lower heater was increased, but this is not limited to this. For example, when a first heater 14A and a second heater 14B are provided above and below, the output of the first heater 14A and the second heater 14B may be the same, i.e., the same amount of heat dissipation. In this case as well, the heat of the lower heater 14A rises, generating convection and effectively heating the space.

The snowfall sensor 1 may be configured to be capable of wireless communication using low power consumption communication with a system such as Bluetooth (registered trademark).

In the above embodiment, the snow melting device 100 is configured to pump up groundwater using a pump, but this is not limited to the above. For example, a sprinkler system that supplies snow melting water from a general water supply pipe, or a non-sprinkler snow melting device such as a heater or other heating device may be used.

The present invention is not limited to the above-mentioned embodiment, and can be modified in various ways without departing from the gist of the present invention. The embodiments may be combined as appropriate, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention.
The following is a description equivalent to the invention described in the claims of the original application.
(1)
Cover and
A sensor unit provided within the cover;
A snowfall sensor comprising: a first heater provided within the cover below the sensor portion.
(2)
The cover has a window portion that transmits light,
the first heater is provided in the cover in a lower region of the first chamber in which the sensor unit is provided or below the window portion;
A snowfall sensor as described in (1).
(3)
The snow sensor according to (2), wherein a substrate is disposed in the first chamber, and the sensor portion and the first heater are disposed in the area between the substrate and the window portion.
(4)
A snowfall sensor as described in any one of (1) to (3), comprising a second heater arranged above the sensor portion.
(5)
A snowfall sensor according to any one of (1) to (4), comprising a plurality of the first heaters.
(6)
The snow sensor according to (4), wherein the output of the first heater disposed below is greater than the output of the second heater disposed above.
(7)
The snow sensor according to claim 4, wherein the heaters are connected in parallel.
(8)
(2) The snowfall sensor according to the present invention;
A snow melting device comprising: a snow melting device connected to the snowfall sensor.

1...snowfall sensor, 2...snow melting equipment, 3...control device, 4...remote control, 10...casing, 11...control board, 12...temperature sensor, 13...distance measurement sensor, 14A, 14B...heater, 15a...connection cable, 15b...connection cable, 15d...pipe member, 16...temperature sensor, 17...body, 17a...opening, 17c...cable hole, 18...cover, 18a...roof portion, 18b...flange portion, 18c...window portion, 18e...protrusion portion, 19a, 19b...partition plate, 19c...slit, 20a...first chamber, 20b...second chamber, 21...memory portion, 22...sensor case, 23...light-emitting portion, 24...light-receiving portion, 25...sensor control unit, 33...display portion, 34...operation portion, 35...output board, 100...snow melting device.

Claims (7)

a casing including a body, a cover having a window portion through which light passes, a sensor portion provided within the cover, and a partition plate;
a first heater provided within the cover below the sensor unit;
Equipped with
The partition plate divides the space of the casing into an upper first chamber and a lower second chamber,
A substrate is disposed in the first chamber;
The partition plate holds the substrate,
the substrate divides the first chamber into front and rear portions,
the first heater is provided in the cover, in the first chamber which is divided into front and rear by the substrate, on the same side as the sensor unit with respect to the substrate, in a lower region or below the window portion;
the sensor portion and the first heater are disposed in a region between the substrate and the window portion ;
Snowfall sensor. The snow sensor according to claim 1 , wherein an inner wall of the roof portion of the cover is formed with an engagement surface that engages with a peripheral edge of the base plate. The snow sensor of claim 1 , wherein the substrate is disposed through the partition plate. a second heater disposed above the sensor portion ;
The heaters are connected in parallel,
4. The snow sensor according to claim 1 , wherein an output of the first heater disposed below is greater than an output of the second heater disposed above . The snow sensor according to any one of claims 1 to 4, comprising a plurality of the first heaters. Equipped with a temperature sensor to detect the air temperature,
The snowfall sensor of claim 4, further comprising a control unit that starts switching current for the first heater and the second heater for a time period of a preset first duty ratio when the air temperature detected by the temperature sensor drops below a predetermined heater operation first temperature, changes switching current to a time period of a second duty ratio greater than the first duty ratio when the air temperature drops below a heater operation second temperature set lower than the heater operation first temperature, changes switching current to a time period of the first duty ratio when the air temperature rises above a reference temperature set higher than the heater operation first temperature, and stops switching current when the air temperature rises above a heater stop temperature set higher than the reference temperature. A snow sensor according to any one of claims 1 to 6 ,
A snow melting device comprising: a snow melting device connected to the snowfall sensor.