JP2009243100A - Screed plate heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of a conventional hot air screed plate heating device wherein if a blower for blowing hot air into a duct fails, flame is reversely blown from a burner, or when the ignition of the burner is failed, unburned LP gas remains in the duct and a risk of explosion of the gas is generated if the gas is flash ignited. <P>SOLUTION: An electric energy is converted into a heat energy by a heater 51L, and the air in a heating part 39L is heated to generate hot air. The hot air generated by the heater 51L is fed, as hot air, to a forward passage A in the duct on a screen plate 31L by a fan 38L, flows while heating, by heat transfer, the half of the upper surface of the screed plate 31L, and flows into a return passage B in the duct after returning at the end of a partition plate 34L. The hot air flowing into the return passage B is reheated by a reheating heater 52L, flows while heating the remaining half of the upper surface of the screed plate 31L, and is sucked to the fan 38L. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a screed plate heating apparatus for heating a screed plate that spreads a heating mixture and smoothes a paved surface.

  Conventionally, as this type of screed plate heating device, for example, as shown in FIG. 1A provided in a pavement machine such as an asphalt finisher using a burner (combustor) using LP (liquefied petroleum) gas as fuel. There is something.

  This figure is a view of the screed as seen from the back. A duct 2 is provided on the top of the screed plate 1, and a burner 3 is provided above the right end of the duct 2. In the burner 3, LP gas supplied from the LP gas cylinder 4 is burned. The hot air 5 generated by this combustion is guided into the duct 2 together with the combustion gas by a blower (blower) 7 for taking in the outside air 6 provided at the upper part of the burner 3, and screed from a plurality of holes 8 provided in the lower surface of the duct 2. Sprayed onto the plate 1. The screed plate 1 is heated by blowing hot air 5. The exhaust 9 after heating the screed plate 1 is discharged to the outside through the exhaust duct 10.

  As such a hot air type heating device, for example, there is one disclosed in Patent Document 1. Patent Document 1 discloses a heating device that guides hot air generated by combustion of a burner to a hollow portion in a deflector plate and heats the deflector plate.

  Conventionally, as an electric heating type screed plate heating apparatus that does not use a burner as described above, for example, there is one shown in FIG.

This figure is a view of the screed as seen from above, and this screed plate heating device supplies a current from a power source 13 to a sheath heater 12 provided on the screed plate 11 to cause the sheath heater 12 to generate heat. The sheath heater 12 is pressed against the screed plate 11 by the holding plate 14, and the screed plate 11 is heated by heat conduction from the sheath heater 12.
Japanese Patent Laid-Open No. 11-124812 (see paragraph [0016] and FIG. 3)

  However, the conventional hot air type screed plate heating apparatus as shown in FIG. 1A is very hot because the hot air 5 for heating the screed plate 1 is generated by the combustion of LP gas. Accordingly, when the entire amount of the hot air 5 is blown directly onto the screed plate 1, only a part of the screed plate 1 to which the hot air 5 is directly blown becomes abnormally high, and that part is damaged. As a countermeasure, the position where the holes 8 are provided in the duct 2 is adjusted so as to obtain a uniform temperature distribution. However, the portion heated by the hot air 5 ejected from the holes 8 in the vicinity of the holes 8 and the holes 8 A temperature difference inevitably occurs in the portion heated at a position away from the center. For this reason, the temperature distribution of the screed plate 1 was not sufficiently uniform.

  In addition, in the conventional hot air type screed plate heating device as shown in FIG. 1A, the flame burns back from the burner 3 when the blower 7 for blowing the hot air 5 into the duct 2 fails. If ignition of the burner 3 fails, there is a risk that unburned LP gas will accumulate in the duct 2 and cause an explosion when ignited. The exhaust 9 discharged from the exhaust duct 10 is still at a high temperature, although the screed plate 1 is heated and the temperature is lowered. For this reason, when a person touches the exhaust duct 10, there is a risk of burns.

  Further, in the conventional electric heating type screed plate heating apparatus as shown in FIG. 1B, the sheath heater 12 as a heat source has a linear shape, and heat is generated by heat conduction from the linear heat source. The entire screed plate 11 having a large area is heated. For this reason, it takes time to raise the temperature of the screed plate 11 as compared with the configuration in which hot air is blown onto the screed plate to heat it. The screed plate 11 vibrates due to the influence of a tamper device that compacts the pavement surface during construction of the pavement surface. For this reason, the heating element such as the sheath heater 12 provided in contact with the screed plate 11 is exposed to the same vibration as the screed plate 11 and has a high probability of failure.

  The present invention has been made to solve such a problem, and in a screed plate heating apparatus for heating a screed plate that spreads a heating mixture and smoothes a paved surface to convert electric energy into heat energy. And hot air generating means for generating hot air, and hot air sending means for sending the hot air generated by the hot air generating means onto the screed plate as hot air.

  According to this configuration, the hot air generating means converts electric energy into heat energy and heats the air to generate hot air. Therefore, the generated hot air is as hot as the hot air generated by the combustion of LP gas. Don't be. Accordingly, only a part of the screed plate to which the hot air is directly blown becomes abnormally high temperature, and the part does not break. In addition, since only a part of the screed plate to which hot air is directly blown does not become abnormally hot, there is not much difference in temperature between the part to which hot air is blown directly and the part that is heated away from that part. The temperature distribution of the screed plate becomes almost uniform.

  Moreover, since the hot air generating means converts electric energy into heat energy and heats the air to generate hot air, it is not necessary to use LP gas that burns the burner. For this reason, as in the conventional case, when the blower breaks down, there is a risk that the flame will backfire from the burner, or when the burner fails to ignite, unburned LP gas accumulates on the screed plate and ignites. There is no risk of explosion.

  Further, since the hot air generated by the hot air generating means is sent as hot air onto the screed plate by the hot air sending means, it is heated as compared with the conventional configuration in which the screed plate is heated by heat conduction using a linear sheath heater. The entire screed plate having a large area can be heated in a short time. Further, unlike a conventional heating element such as a sheathed heater, it is not configured to provide hot air generating means and hot air sending means in contact with the screed plate, so that the hot air generating means and hot air sending means are not exposed to the vibration of the screed plate. In fact, it is possible to reduce the probability that the hot air generating means and the hot air sending means will fail.

  Further, the present invention is characterized in that a hot air circulation path is provided for returning the hot air sent onto the screed plate by the hot air sending means to circulate on the screed plate.

  According to this configuration, the exhaust air that is sent as hot air on the screed plate by the hot air sending means and heats the screed plate flows through the hot air circulation path and circulates on the screed plate without being discharged outside. For this reason, even if the screed plate is heated, the heat remaining in the exhaust is reused without being discharged outside the hot air circulation path, so that the heat efficiency is good and the amount of electrical energy consumed by the hot air generating means can be kept small. it can. Further, since the hot air is not discharged outside the hot air circulation path, an exhaust port is not required, and it is possible to eliminate the risk of a human being touching the exhaust port and being burned as in the prior art.

  In addition, the present invention is characterized by comprising reheating means for reheating the hot air sent out from the hot air sending means.

  According to this configuration, when the screed plate having a large size is heated, the reheating unit reheats the hot air even if the temperature of the hot air sent from the hot air sending unit is lowered while moving on the screed plate. Therefore, the temperature of the entire screed plate can be kept uniform.

  In the screed plate heating apparatus according to the present invention, as described above, only a part of the screed plate to which hot air is directly blown becomes abnormally high temperature, and the part does not break. Further, the temperature difference between the portion where the hot air is directly blown and the portion heated away from the portion does not occur so much, and the temperature distribution of the screed plate becomes almost uniform. In addition, there is no risk of the flame from flashing back from the burner, or the risk of explosion when the unburned LP gas accumulated on the screed plate is ignited. Further, the entire screed plate can be heated in a short time, and the probability that the hot air generating means and the hot air sending means will fail due to the vibration of the screed plate can be reduced.

  Next, the best mode for carrying out the present invention will be described.

  FIG. 2 is a partially broken side view schematically showing the configuration of the asphalt finisher 21 provided with the screed plate heating device according to the best mode.

  The asphalt finisher 21 is provided with a hopper 22 on which the asphalt heating mixture k is loaded at the front of the vehicle body. A conveyor 23 for conveying the asphalt heating mixture k loaded on the hopper 22 is provided at the lower part of the vehicle body behind the hopper 22, and a screw spreader 24 is provided at the lower part of the vehicle body further behind the conveyor 23. The screw spreader 24 has screw blades formed on the outer periphery of the screw shaft. As the screw shaft rotates at a constant speed, the screw blades swirl and are supplied from the conveyor 23 and fall on the road surface R. Is spread in the width direction of the road surface R. A screed device 25 is provided at the rear of the vehicle body to spread the spread asphalt heating mixture k and smooth the paved surface. The screed device 25 is provided with a screed plate heating device described later. The asphalt finisher 21 travels to the left in the figure, which is the traveling direction, by the pair of front drive wheels 26L and 26R and the pair of rear drive wheels 27L and 27R, and pulls the screed device 25. An operation unit 28 is provided in the driver's seat at the upper part of the vehicle body. The operation unit 28 is provided with an operation lever, an operation switch, and the like for operating the screed device 25.

  3A is a plan view of the screed device 25 shown in FIG. 2, and FIG. 3B is a rear front view thereof.

In the screed plate heating device according to the present embodiment, the left half screed plate heating device and the right half screed plate heating device are formed symmetrically about the machine center C of the asphalt finisher 21. The left half screed plate 31L is supported on the vehicle body of the asphalt finisher 21 by the frame 32L ₁ and the frame 32L ₂ , and the right half screed plate 31R is supported by the frame 32R ₁ and the frame 32R ₂ .

In the center of the screed unit 25 sandwiched between the frame 32L ₁ and frame 32R ₁ is heated portion mount 41L, 41R are provided in the side wall of each frame _32L 1, 32R _1. The heating units 39L and 39R are installed on the heating unit mounting bases 41L and 41R via the anti-vibration rubbers 40L and 40R. The anti-vibration rubbers 40L and 40R absorb vibrations caused by the tamper device that compacts the pavement surface during construction of the pavement and prevents it from being transmitted to the heating units 39L and 39R. Fans 38L and 38R are installed above the heating units 39L and 39R. These fans 38L and 38R are connected to ducts to be described later by flexible pipes 36L and 36R penetrating the frames 32L ₁ and 32R ₁ . The heating units 39L and 39R are also connected to ducts described later by flexible pipes 37L and 37R penetrating the frames 32L ₁ and 32R ₁ .

  4A is a front perspective view of the left half from the machine center C of the screed device 25 shown in FIG. 3, and FIG. 4B is broken along the line IIIb-IIIb in FIG. It is arrow sectional drawing. In this figure, the same parts as those in FIG.

Screed plate heating apparatus, the left half of the duct is provided between the frame 32L ₁ and frame 32L _2. This duct is formed with left and right side surfaces surrounded by frames 32L ₁ and 32L ₂ , front and rear side surfaces surrounded by duct walls 33L and 33L, an upper surface surrounded by a heat insulating material 35L, and a lower surface surrounded by a screed plate 31L. In addition, the duct is provided with a partition plate 34L that forms a U-shaped path therein. The U-shaped path in the duct includes an outward path A and a return path B. The forward path A is connected to the flexible pipe 37L, and the return path B is connected to the flexible pipe 36L.

  FIG. 5A is a plan view schematically showing the left half screed plate heating apparatus according to the present embodiment, and FIG. 5B is a rear front view thereof. In the figure, the same parts as those in FIG.

  A heater 51L is provided in the internal space of the heating unit 39L. The heater 51L is made of a nichrome wire or the like that generates Joule heat when an electric current is passed, and is connected to a built-in power source 53 obtained by an AC generator built in the asphalt finisher 21. The heater 51L constitutes hot air generating means for converting electric energy into heat energy to heat the air inside the heating unit 39L and generate hot air. The hot air generated by the heating unit 39L is blown from the heating unit 39L to the forward path A in the duct by the fan 38L provided at the upper part of the heating unit 39L via the flexible pipe 37L. The fan 38L constitutes hot air sending means for sending hot air inside the heating unit 39L generated by the hot air generating means as hot air on the screed plate 31L.

  The hot air sent out on the screed plate 31L first flows in the forward path A in the duct, then turns back at the end of the partition plate 34 and flows into the return path B in the duct, and the screed plate 31L transfers heat from its upper surface. To heat. The hot air after heating the screed plate 31L is sucked into the fan 38L from the return path B in the duct via the flexible pipe 36L. In the forward path A and the return path B of the duct formed in the screed plate heating device, the hot air sent to the screed plate 31L by the hot air sending means is returned to the fan 38L as the hot air sending means to circulate on the screed plate 31L. It constitutes a circulation path.

  In addition, a reheat heater 52L is provided near the start point of the return path B in the duct. Similar to the heater provided in the heating section 39L, the reheating heater 52L is made of nichrome wire or the like that generates Joule heat when an electric current is passed, and is folded back from the end of the partition plate 34 to the return path B in the duct. Reheat hot air flowing in. The reheat heater 52L constitutes a reheat means for reheating the hot air sent out from the fan 38L.

  The right half screed plate heating device (not shown) has the same structure as the left half screed plate heating device described above, and a description thereof will be omitted.

  In the above configuration, electric energy is converted into thermal energy by the heater 51L connected to the built-in power supply 53, and the air inside the heating unit 39L is heated to generate hot air. The hot air generated by the heater 51L is sent out as hot air to the forward path A in the duct on the screed plate 31L by the fan 38L. The hot air sent to the forward path A in the duct flows through the forward path A in the duct while heating the upper surface of the half of the screed plate 31L by heat transfer, and then turns back at the end of the partition plate 34L to return to the return path B in the duct. Flow into. The hot air flowing into the return path B in the duct is heated again by the reheat heater 52L connected to the built-in power supply 53, flows while heating the upper surface of the remaining half of the screed plate 31L, and is sucked into the fan 38L. The absorbed hot air is heated again by the heating unit 39L, sent out into the duct by the fan 38L, and circulates in the forward path A and the return path B.

  In addition, the right half screed plate heating device (not shown) causes the right half screed plate 31R to circulate through the forward and return paths in the duct in the same manner as the left half screed plate 31L. Heated.

  According to the screed plate heating device according to the present embodiment described above, the heater 51L and the heaters constituting the right half screed plate heating device (not shown) convert the electrical energy into heat energy and the air inside the heating units 39L and 39R. In order to generate hot air, the generated hot air is not as hot as the conventional hot air generated by the combustion of LP gas. Therefore, only a part of the screed plates 31L and 31R to which the hot air is directly blown becomes abnormally high in temperature, and the part is not damaged. Moreover, since only a part of the screed plates 31L and 31R to which the hot air is directly blown does not become abnormally high temperature, there is a temperature difference between the part to which the hot air is blown directly and the part to be heated away from the part. The temperature distribution of the screed plates 31L and 31R becomes almost uniform.

  Also, the heater 51L and the heater constituting the right half screed plate heating device (not shown) convert electric energy into heat energy to heat the air inside the heating portions 39L and 39R and generate hot air. No need to use LP gas to burn. For this reason, as in the prior art, when the fans 38L and 38R fail, there is a risk that the flame will backfire from the burner, or when the burner fails to ignite, unburned LP gas is removed from the screed plates 31L and 31R. The danger of exploding when it catches up and ignites is eliminated.

  Further, the hot air generated by the heaters 51L and the heater constituting the right half screed plate heating device (not shown) is sent out as hot air onto the screed plates 31L and 31R by the fans 38L and 38R, and the screed plates 31L and 31R are formed on the surface. Since the heating is performed, the entire screed plates 31L and 31R having a large heating area can be heated in a short time as compared with the conventional configuration in which the screed plate is heated by heat conduction using a linear sheath heater. Further, since the heater and fans 38L and 38R are not provided in contact with the screed plates 31L and 31R like a conventional heating element such as a sheathed heater, the heaters and fans 38L and 38R are caused to vibrate the screed plates 31L and 31R. The probability of failure of the heater and the fans 38L and 38R can be reduced without being exposed. Furthermore, since the heating parts 39L, 39R and the fans 38L, 38R provided with heaters are installed on the heating part mounting bases 41L, 41R via the anti-vibration rubbers 40L, 40R, the screed plates 31L, 31R The probability of failure of the heaters and fans 38L and 38R due to vibration can be further reduced.

  Further, in the present embodiment, the exhaust that has been sent to the screed plates 31L and 31R as hot air by the fans 38L and 38R and heated the screed plates 31L and 31R flows through the hot air circulation path formed by the forward path A and the return path B. It circulates on the screed plates 31L and 31R without being discharged to the outside. For this reason, even if the screed plates 31L and 31R are heated, the heat remaining in the exhaust is reused without being discharged outside the hot air circulation path, so that the heat efficiency is good and the heater 51L and the screed plate heating of the right half (not shown) are heated. The amount of electrical energy consumed by the heater constituting the apparatus can be reduced. Further, since the hot air is not discharged outside the hot air circulation path, an exhaust port is not required, and it is possible to eliminate the risk of a human being touching the exhaust port and being burned as in the prior art.

  In the present embodiment, the upper surface of the hot air circulation path formed by the forward path A and the return path B is covered with the heat insulating materials 35L and 35R. For this reason, the heat dissipation to the upper surface of the screed plates 31L and 31R can be suppressed.

  In the present embodiment, when the screed plates 31L and 31R having a large size are heated, even if the temperature of the hot air sent from the fans 38L and 38R moves on the screed plates 31L and 31R, Since the heater 52L and the reheat heater constituting the right half screed plate heating device (not shown) reheat the hot air, the temperature of the screed plates 31L, 31R as a whole can be kept uniform. Therefore, the temperature difference between hot air between the inlet of hot air blown from the flexible pipes 37L and 37R to the forward path A inside the duct and the outlet of hot air exhausted from the return path B inside the duct to the flexible pipes 36L and 36R becomes small.

  In the present embodiment, one reheating heater that constitutes the reheat heater 52L and the screed plate heating device (not shown) on the right half is provided in the middle of the hot air circulation path formed by the forward path A and the return path B. However, the present invention is not limited to this. For example, a configuration in which a plurality of reheat heaters constituting a reheat heater 52L and a right half screed plate heating device (not shown) may be provided in the middle of the hot air circulation path formed by the forward path A and the return path B is possible. According to this configuration, the temperature of the entire screed plates 31L and 31R can be kept more uniform.

  In the above-described embodiment, the case where the heating units 39L and 39R are installed on the heating unit mounting bases 41L and 41R via the anti-vibration rubbers 40L and 40R has been described, but the present invention is limited to this. is not. For example, a configuration using an elastic member such as a spring instead of the anti-vibration rubbers 40L and 40R may be used. Even in this configuration, the same effects as those of the above-described embodiment can be obtained.

  In the above embodiment, the screed plate heating apparatus according to the present invention is applied to the screed plate heating apparatus in the asphalt finisher, but the present invention is not limited to this. For example, the present invention can also be applied to a screed plate heating device for a road surface layer regenerator such as a remixer or a re-paver.

(A) is the conceptual diagram which looked at the conventional hot-air type screed plate heating apparatus using a burner from the back, (b) looked at the conventional electric heating type screed plate heating apparatus using a sheath heater from the top. It is a conceptual diagram. It is a partially broken side view which shows the outline of a structure of the asphalt finisher provided with the screed plate heating apparatus by this embodiment. (A) is the top view of the screed apparatus shown in FIG. 2, The same figure (b) is the back front view. (A) is a front perspective view of the left half of the screed device shown in FIG. 3, and (b) is a cross-sectional view taken along the line IIIb-IIIb in FIG. (A) is a top view which shows the outline of the screed plate heating apparatus of the left half by this embodiment, The same figure (b) is the back front view.

Explanation of symbols

25 ... screed apparatus 31L, 31R ... screed plates _{32L 1, 32L 2, 32R 1} , 32R 2 ... frame 33L, 33R ... duct wall 34L ... partition plate 35L, 35R ... heat insulating material 36L, 37L, 36R, 37R ... Flexible pipe 38L , 38R ... Fan 39L, 39R ... Heating part 51 ... Heater 52 ... Reheat heater

Claims (3)

In a screed plate heating device that heats a screed plate that spreads a heating mixture and smoothes the paved surface,
It comprises hot air generating means for converting electric energy into heat energy to heat air to generate hot air, and hot air sending means for sending hot air generated by the hot air generating means as hot air on the screed plate. A screed plate heating device.   The screed plate heating according to claim 1, further comprising a hot air circulation path for returning the hot air sent out on the screed plate by the hot air sending means to the hot air sending means and circulating the hot air on the screed plate. apparatus.   The screed plate heating apparatus according to claim 1 or 2, further comprising reheating means for reheating hot air sent from the hot air sending means.

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