A dryer for recycling waste sawdust

Abstract

The present invention relates to the technical field of drying treatment, and in particular to a dryer for recycling and treating waste sawdust, which comprises a drying box and a fluidizing mechanism, wherein the drying box is in the shape of a ring, and its cross-sectional shape is formed by splicing two left and right ellipses, and the long axis of the ellipses is vertical; the drying box is composed of a first sub-box body and a second sub-box body, the first sub-box body is located on the top of the second sub-box body, and the first sub-box body and the second sub-box body form a complete chamber; by setting the shape of the drying box to a ring, and setting its cross-sectional shape to a shape composed of two ellipses, the waste sawdust can be continuously fluidized and dried in the drying box by means of the effect of hot air flow discharged from air holes, so that the waste sawdust is always in a dispersed state, which facilitates the hot air flow to fully and comprehensively contact with the waste sawdust, and effectively improves the drying speed and drying effect.

Description

Technical Field

[0001] The present invention relates to the technical field of drying treatment, and in particular to a dryer for recycling waste sawdust. Background Technology

[0002] Waste sawdust is the main waste product of various wood processing. Due to its fluffy structure, light weight and easy combustion, it can be used as fuel, which can not only prevent sawdust from damaging the environment, but also avoid harm to the human body when inhaling sawdust, and at the same time achieve the effect of resource recycling. When processing waste sawdust, it is necessary to remove the moisture in it first, that is, to dry the waste sawdust. Generally, the dryer uses the method of blowing hot air flow to the waste sawdust in the conveying state for heating and drying. However, this drying method is not thorough, and high-temperature air is not easy to enter the piled waste sawdust, resulting in the inability to fully dry the waste sawdust. At the same time, the waste sawdust blocks each other, which easily causes slow evaporation of moisture and affects the drying efficiency. SUMMARY OF THE INVENTION

[0003] In order to solve the above technical problems, the present invention provides a dryer for recycling and processing waste sawdust.

[0004] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0005] A dryer for recycling and processing waste sawdust, comprising a drying box and a fluidizing mechanism, wherein the drying box is annular in shape, and its cross-sectional shape is formed by splicing two left and right ellipses, and the long axis of the ellipses is vertical;

[0006] The drying box is composed of a first sub-box body and a second sub-box body, the first sub-box body is located on the top of the second sub-box body, and the first sub-box body and the second sub-box body form a complete chamber, and the bottom of the inner wall of the first sub-box body is provided with a plurality of vertical plates in a ring shape;

[0007] The fluidization mechanism comprises an annular channel arranged at the bottom of the second sub-box body, the annular channel penetrates into the second sub-box body, and a plurality of air holes are opened on the outer wall of the annular channel in the second sub-box body, and the direction of the air holes is inclined downward;

[0008] Wherein, a partition is vertically arranged in the second sub-box body, the partition separates the annular space in the second sub-box body, and the partition extends into the annular channel, the partition separates the annular space in the annular channel, and a feed hopper and a discharge pipe are connected and arranged on the outer wall of the second sub-box body, the feed hopper and the discharge pipe are respectively located on the front and rear sides of the partition, the feed hopper is connected to the side wall of the second sub-box body, and the discharge pipe is connected to the bottom of the second sub-box body.

[0009] Preferably, a flat plate is provided at the top of the partition plate. When the vertical plate moves to the position of the flat plate, the upper surface of the flat plate is in sliding contact with the bottom of the vertical plate, and the flat plate is in contact with at least one vertical plate of the first sub-chamber.

[0010] Preferably, an annular baffle is provided at the top of the annular channel, and the cross-section of the annular baffle is conical.

[0011] Preferably, a gas circulation mechanism is further included. The gas circulation mechanism is used to continuously supply hot air flow into the second sub-chamber. The gas circulation mechanism includes an air suction hopper, a first air pipe, an air delivery pump, an electric heating box and a second air pipe. The air suction hopper and the output end of the second air pipe are respectively located on the front and rear sides of the partition plate. The air suction hopper is communicated with the outer wall of the second sub-chamber. The input end of the air delivery pump is communicated with the air suction hopper through the first air pipe. The output end of the air delivery pump is communicated with the electric heating box. The bottom of the electric heating box is communicated with the input end of the second air pipe. Both the air delivery pump and the electric heating box are fixed on the outer wall of the second sub-chamber.

[0012] Preferably, the air suction hopper is inclined downward, and a filter screen for intercepting waste sawdust is provided in the air suction hopper.

[0013] Preferably, gaps are formed on the left and right sides of each vertical plate. Two retaining rings are provided on the inner wall of the second sub-chamber. The two retaining rings are respectively located at the two annular edge positions of the top opening of the second sub-chamber. The top of the retaining ring extends into the first sub-chamber, and the outer wall of the retaining ring is close to the inner wall of the first sub-chamber.

[0014] A sliding groove is formed on the circumferential outer wall of the first sub-chamber, and a plurality of sliders are slidably arranged in the sliding groove. The sliders are fixedly connected with the outer wall of the second sub-chamber through support plates.

[0015] Preferably, a fixing plate is provided on the outer wall at the middle position of the second sub-chamber, a first motor is fixed on the fixing plate, a gear is provided at the upper output end of the first motor, a toothed ring is provided on the outer wall at the middle position of the first sub-chamber, and the gear is meshed with the toothed ring.

[0016] Preferably, a crushing mechanism is provided in the feed hopper. The crushing mechanism is used to crush the agglomerated waste sawdust entering the feed hopper. The crushing mechanism includes a plurality of rotating shafts arranged side by side and rotatably installed on the inner wall of the feed hopper. Crushing rods are provided on the rotating shafts. The ends of the rotating shafts extend outside the feed hopper, and transmission wheels are provided at the ends of the rotating shafts. Adjacent two transmission wheels are meshed and driven with each other. A second motor is fixed on the feed hopper, and the output end of the second motor is drivingly connected with one transmission wheel.

[0017] The beneficial effects of the present invention compared with the prior art are as follows: By setting the shape of the drying box as annular and the cross-sectional shape as a shape composed of two ellipses, the waste sawdust can be continuously fluidized and dried in the drying box by means of the hot air flow discharged through the air holes, so that the waste sawdust is always in a dispersed state, which is convenient for the hot air flow to fully and comprehensively contact with the waste sawdust, effectively improving the drying speed and drying effect. At the same time, combined with the continuous rotation of the first sub-box and multiple vertical plates thereon, the rotary conveying of the waste sawdust in the fluidized state can be realized, so as to convey the waste sawdust from the feed hopper to the discharge pipeline and achieve the continuous drying of the waste sawdust. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 is the structural schematic diagram of the present invention;

[0020] Figure 2 is Figure 1 the top view structural schematic diagram in

[0021] Figure 3 is Figure 1 the bottom view structural schematic diagram in

[0022] Figure 4 is Figure 1 the partial enlarged structural schematic diagram of the drying box in

[0023] Figure 5 is Figure 1 the enlarged bottom view structural schematic diagram of the first sub-box in

[0024] Figure 6 is Figure 1 the enlarged top view structural schematic diagram of the second sub-box in

[0025] Figure 7 is Figure 1 the partial enlarged structural schematic diagram of the feed hopper in

[0026] Reference numerals in the drawings: 1, first sub-chamber body; 2, second sub-chamber body; 3, vertical plate; 4, annular channel; 5, air injection hole; 6, partition board; 7, feed hopper; 8, discharge pipeline; 9, flat plate; 10, annular baffle; 11, suction hopper; 12, first air pipe; 13, air delivery pump; 14, electric heating box; 15, second air pipe; 16, retaining ring; 17, slider; 18, support plate; 19, fixing plate; 20, first motor; 21, gear; 22, toothed ring; 23, rotating shaft; 24, crushing rod; 25, transmission wheel; 26, second motor. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0028] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0029] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. This embodiment is written in a progressive manner.

[0030] As Figures 1 to 7 shown, a dryer for waste sawdust recycling and treatment according to the present invention includes a drying box and a fluidization mechanism. The drying box is annular in shape, and its cross-sectional shape is composed of two left and right ellipses spliced together, and the long axis of the ellipse is vertical;

[0031] The drying box is composed of a first sub-chamber body 1 and a second sub-chamber body 2. The first sub-chamber body 1 is located on the top of the second sub-chamber body 2, and the first sub-chamber body 1 and the second sub-chamber body 2 form a complete chamber. A plurality of vertical plates 3 are arranged in a ring shape at the bottom of the inner wall of the first sub-chamber body 1;

[0032] The fluidization mechanism includes an annular channel 4 provided at the bottom of the second sub-chamber 2. The annular channel 4 penetrates into the second sub-chamber 2. A plurality of air-blowing holes 5 are formed on the outer wall of the annular channel 4 in the second sub-chamber 2, and the direction of the air-blowing holes 5 is inclined downward;

[0033] Wherein, a partition plate 6 is vertically arranged in the second sub-chamber 2. The partition plate 6 separates the annular space in the second sub-chamber 2, and the partition plate 6 extends into the annular channel 4 to separate the annular space in the annular channel 4. A feed hopper 7 and a discharge pipeline 8 are communicated and arranged on the outer wall of the second sub-chamber 2. The feed hopper 7 and the discharge pipeline 8 are respectively located on the front and rear sides of the partition plate 6. The feed hopper 7 is communicated with the side wall of the second sub-chamber 2, and the discharge pipeline 8 is communicated with the bottom of the second sub-chamber 2.

[0034] Specifically, a plurality of air holes 5 are arranged in two elliptical spaces on the drying box, and the direction of the air holes 5 is inclined toward the bottom of the elliptical inner wall of the drying box, so that when the hot air flow is discharged from the air holes 5, the hot air flow can flow upward along the elliptical inner wall of the drying box. In this way, when there is waste sawdust in the drying box, the hot air flow can push the waste sawdust to move upward along the two elliptical inner walls of the drying box. When the waste sawdust reaches the upper side of the drying box, due to the limitation of the shape of the drying box, the waste sawdust will gather toward the middle of the drying box and fall again to the vicinity of the annular channel 4. At this time, the waste sawdust discharged from the air holes 5 The hot air flow will blow the waste sawdust upward again, thereby achieving a continuous fluidization effect of the waste sawdust. At this time, the waste sawdust is in a flying and scattered state, so that the hot air flow can fully contact with the dispersed waste sawdust, which is convenient for comprehensive and rapid drying of the waste sawdust. Since the partition 6 separates the annular space inside the second sub-box 2 and the annular space inside the annular channel 4, the hot air flow discharged into the annular channel 4 can flow from one side wall of the partition 6 along the annular trajectory of the annular channel 4 to the other side wall of the partition 6, so that the hot air flow fully fills the annular channel 4, and the annular channel 4 The hot air flow can be discharged through the multiple air holes 5 thereon, thereby realizing the comprehensive fluidization drying working mode of the waste sawdust in the second sub-box body 2. At the same time, when the waste sawdust is discharged into the second sub-box body 2 through the feed hopper 7, the first sub-box body 1 is rotated, and the first sub-box body 1 can carry the multiple vertical plates 3 thereon to rotate. When the waste sawdust moves upward in fluidization to between two adjacent vertical plates 3 in the first sub-box body 1, the moving vertical plates 3 will carry the waste sawdust along the circular trajectory of the second sub-box body 2 for a certain distance, and the waste sawdust falls synchronously during the movement. With the continuous rotation of the first sub-box body 1 and the waste sawdust The waste sawdust is continuously fluidized, so that the waste sawdust moves from one side wall of the partition 6 to the other side wall of the partition 6 along the circular trajectory of the second sub-box 2, so that the waste sawdust can be transported in the second sub-box 2 in an annular manner, and the waste sawdust is continuously in a fluidized drying state during transportation. When the dry waste sawdust moves to the position of the discharge pipe 8, the waste sawdust will be naturally discharged through the discharge pipe 8, thereby realizing the continuous drying of the waste sawdust. At the same time, the rotation of the first sub-box 1 and the multiple vertical plates 3 can also promote the hot air flow in the drying box to rotate and flow along the circular trajectory of the second sub-box 2.

[0035] By setting the shape of the drying box to be annular and its cross-sectional shape to be a shape composed of two ellipses, the waste sawdust can be continuously fluidized and dried in the drying box by means of the hot air flow discharged from the air blast holes 5, so that the waste sawdust is always in a dispersed state, which facilitates the hot air flow to fully and comprehensively contact the waste sawdust, effectively improving the drying speed and drying effect. At the same time, combined with the continuous rotation of the first sub-box 1 and the multiple vertical plates 3 thereon, the waste sawdust can be rotated and transported in a fluidized state, thereby transporting the waste sawdust from the feed hopper 7 to the discharge pipe 8, and realizing the continuous drying of the waste sawdust.

[0036] Preferably, a flat plate 9 is provided on the top of the partition plate 6. When the vertical plate 3 moves to the position of the flat plate 9, the upper surface of the flat plate 9 is in sliding contact with the bottom of the vertical plate 3, and the flat plate 9 is in contact with at least one vertical plate 3 on the first sub-chamber 1.

[0037] Specifically, due to the large gap between two adjacent vertical plates 3, when two adjacent vertical plates 3 are respectively located on the front and back sides of the partition plate 6, the spaces on the front and back sides of the partition plate 6 will be connected through the space between the two adjacent vertical plates 3. At this time, waste sawdust or hot air flow will directly move from one side of the partition plate 6 to the other side through the space between the two adjacent vertical plates 3, so that the drying work of the waste sawdust cannot be realized. Therefore, it is necessary to set the flat plate 9 to block it. Since the flat plate 9 is in contact with at least one vertical plate 3 on the first sub-chamber 1, and the first sub-chamber 1 and the multiple vertical plates 3 rotate unidirectionally, the spaces on the front and back sides of the partition plate 6 cannot be connected through the space between the two adjacent vertical plates 3, so that the dynamic isolation of the spaces on the front and back sides of the partition plate 6 is realized.

[0038] Preferably, an annular baffle 10 is provided on the top of the annular channel 4, and the cross section of the annular baffle 10 is conical.

[0039] Specifically, by setting the annular baffle 10, it is convenient to guide the waste sawdust falling in the drying box, avoid the deposition of waste sawdust on the top of the annular channel 4, and avoid the waste sawdust from entering the air holes 5. At the same time, the conical surface of the annular baffle 10 can play a role in guiding the hot air flow discharged from the air holes 5.

[0040] Preferably, a gas circulation mechanism is further included. The gas circulation mechanism is used to continuously transport hot air flow into the second sub-chamber 2. The gas circulation mechanism includes an air suction hopper 11, a first air pipe 12, an air delivery pump 13, an electric heating box 14 and a second air pipe 15. The air suction hopper 11 and the output end of the second air pipe 15 are respectively located on the front and back sides of the partition plate 6. The air suction hopper 11 is communicated with the outer wall of the second sub-chamber 2. The input end of the air delivery pump 13 is communicated with the air suction hopper 11 through the first air pipe 12. The output end of the air delivery pump 13 is communicated with the electric heating box 14. The bottom of the electric heating box 14 is communicated with the input end of the second air pipe 15. The air delivery pump 13 and the electric heating box 14 are both fixed on the outer wall of the second sub-chamber 2.

[0041] Specifically, the air delivery pump 13 evacuates the air in the second sub-chamber 2 on one side of the partition plate 6 through the first air pipe 12 and the air suction hopper 11 and discharges the air into the electric heating box 14. The electric heating box 14 heats the air to form a hot air flow, and the hot air flow is discharged into the electric heating box 14 through the second air pipe 15, so that a circulating flow state of the hot air flow in the second sub-chamber 2 is formed.

[0042] Preferably, the air suction hopper 11 is inclined downward, and a filter screen for intercepting waste sawdust is arranged in the air suction hopper 11.

[0043] Specifically, the filter screen can prevent waste sawdust from entering the gas circulation mechanism.

[0044] More preferably, openings are formed on both the left and right sides of each vertical plate 3, and two retaining rings 16 are arranged on the inner wall of the second sub-chamber 2. The two retaining rings 16 are respectively located at the two annular edges of the top opening of the second sub-chamber 2. The top of the retaining ring 16 extends into the first sub-chamber 1, and the outer wall of the retaining ring 16 is close to the inner wall of the first sub-chamber 1.

[0045] A sliding groove is formed on the circumferential outer wall of the first sub-chamber 1, and a plurality of sliders 17 are slidably arranged in the sliding groove. The sliders 17 are fixedly connected to the outer wall of the second sub-chamber 2 through support plates 18.

[0046] Specifically, since the first sub-chamber 1 needs to rotate on the second sub-chamber 2, in order to prevent friction damage between the first sub-chamber 1 and the second sub-chamber 2, a small gap needs to be left between the first sub-chamber 1 and the second sub-chamber 2. The retaining ring 16 blocks this gap to reduce air circulation. At the same time, since the retaining ring 16 extends upward to block the gap, it will not affect the fluidized waste sawdust in the drying box. The sliders 17 and the support plates 18 support the first sub-chamber 1.

[0047] More preferably, a fixing plate 19 is arranged on the outer wall at the middle position of the second sub-chamber 2. A first motor 20 is fixed on the fixing plate 19. A gear 21 is arranged on the upper output end of the first motor 20. A toothed ring 22 is arranged on the outer wall at the middle position of the first sub-chamber 1. The gear 21 meshes with the toothed ring 22.

[0048] Specifically, the first motor 20 can drive the first sub-chamber 1 to rotate through the gear 21 and the toothed ring 22, thereby providing power for the first sub-chamber 1. The fixing plate 19 supports the first motor 20.

[0049] More preferably, a crushing mechanism is arranged in the feed hopper 7. The crushing mechanism is used for crushing the agglomerated waste sawdust entering the feed hopper 7. The crushing mechanism includes a plurality of rotating shafts 23 rotatably installed side by side on the inner wall of the feed hopper 7. A plurality of crushing rods 24 are arranged on the rotating shafts 23. The ends of the rotating shafts 23 extend outside the feed hopper 7, and transmission wheels 25 are arranged at the ends of the rotating shafts 23. Adjacent two transmission wheels 25 are meshed and driven with each other. A second motor 26 is fixed on the feed hopper 7. The output end of the second motor 26 is in transmission connection with one of the transmission wheels 25.

[0050] Specifically, the second motor 26 can drive multiple transmission wheels 25 to rotate synchronously, thereby driving multiple rotating shafts 23 and multiple crushing rods 24 to rotate synchronously. The crushing rods 24 can crush the waste sawdust entering the feed hopper 7, thereby preventing the waste sawdust from caking and affecting the drying effect in the second sub-case 2.

[0051] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A dryer for recycling waste sawdust, characterized in that: It includes a drying box and a fluidizing mechanism. The drying box is annular in shape, and its cross-section is formed by splicing two ellipses on the left and right, and the long axis of the ellipses is vertical. The drying box is composed of a first sub-box body (1) and a second sub-box body (2), the first sub-box body (1) is located on the top of the second sub-box body (2), and the first sub-box body (1) and the second sub-box body (2) form a complete chamber, and a plurality of vertical plates (3) are arranged in a ring shape at the bottom of the inner wall of the first sub-box body (1); The fluidizing mechanism comprises an annular channel (4) arranged at the bottom of the second sub-box (2), the annular channel (4) penetrates into the second sub-box (2), a plurality of air holes (5) are provided on the outer wall of the annular channel (4) in the second sub-box (2), and the air holes (5) are inclined downward; A partition (6) is vertically arranged in the second sub-box (2), the partition (6) partitions the annular space in the second sub-box (2), and the partition (6) extends into the annular channel (4), the partition (6) partitions the annular space in the annular channel (4), a feed hopper (7) and a discharge pipe (8) are arranged on the outer wall of the second sub-box (2), the feed hopper (7) and the discharge pipe (8) are respectively located on the front and rear sides of the partition (6), the feed hopper (7) is connected to the side wall of the second sub-box (2), and the discharge pipe (8) is connected to the bottom of the second sub-box (2); Each vertical plate (3) is provided with notches on both sides thereof. Two retaining rings (16) are provided on the inner wall of the second sub-box body (2). The two retaining rings (16) are respectively located at two annular edge positions of the top opening of the second sub-box body (2). The top of the retaining ring (16) extends into the first sub-box body (1), and the outer wall of the retaining ring (16) is close to the inner wall of the first sub-box body (1). A slide groove is provided on the circumferential outer wall of the first sub-box body (1), a plurality of sliding blocks (17) are slidably arranged in the slide groove, and the sliding blocks (17) are fixedly connected to the outer wall of the second sub-box body (2) via a support plate (18); A fixing plate (19) is arranged on the outer wall at the middle position of the second sub-box body (2), a first motor (20) is fixed on the fixing plate (19), a gear (21) is arranged at the upper output end of the first motor (20), and a gear ring (22) is arranged on the outer wall at the middle position of the first sub-box body (1), the gear (21) meshing with the gear ring (22).

2. A dryer for recycling waste sawdust as claimed in claim 1, characterized in that: A flat plate (9) is arranged on the top of the partition (6); when the vertical plate (3) moves to the position of the flat plate (9), the upper surface of the flat plate (9) slides in contact with the bottom of the vertical plate (3), and the flat plate (9) contacts at least one vertical plate (3) on the first sub-box (1).

3. A dryer for recycling waste sawdust as claimed in claim 2, characterized in that: An annular baffle (10) is provided at the top of the annular channel (4), and the cross section of the annular baffle (10) is conical.

4. A dryer for recycling waste sawdust as claimed in claim 3, characterized in that: The invention also comprises a gas circulation mechanism, the gas circulation mechanism being used for continuously conveying a hot gas flow into the second sub-box body (2), the gas circulation mechanism comprising an air suction hopper (11), a first air pipe (12), an air delivery pump (13), an electric heating box (14) and a second air pipe (15), the output ends of the air suction hopper (11) and the second air pipe (15) being respectively located at the front and rear sides of the partition (6), the air suction hopper (11) being connected to the outer wall of the second sub-box body (2), the input end of the air delivery pump (13) being connected to the air suction hopper (11) through the first air pipe (12), the output end of the air delivery pump (13) being connected to the electric heating box (14), the bottom of the electric heating box (14) being connected to the input end of the second air pipe (15), and the air delivery pump (13) and the electric heating box (14) being fixed to the outer wall of the second sub-box body (2).

5. The dryer for recycling waste sawdust as claimed in claim 4, characterized in that: The air suction hopper (11) is inclined downward, and a filter screen for intercepting waste sawdust is arranged inside the air suction hopper (11).

6. A dryer for recycling waste sawdust as claimed in claim 5, characterized in that: A crushing mechanism is provided in the feed hopper (7), and is used for crushing the agglomerated waste sawdust entering the feed hopper (7). The crushing mechanism comprises a plurality of rotating shafts (23) rotatably mounted side by side on the inner wall of the feed hopper (7), a plurality of crushing rods (24) are provided on the rotating shafts (23), the ends of the rotating shafts (23) extend outside the feed hopper (7), and a transmission wheel (25) is provided at the ends of the rotating shafts (23), two adjacent transmission wheels (25) are meshed with each other for transmission, a second motor (26) is fixed on the feed hopper (7), and an output end of the second motor (26) is transmission-connected to a transmission wheel (25).

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