Power unit and work vehicle

Abstract

In a power unit in which the engine and motor generator are connected by a transmission belt, wear on the tension pulley is suppressed. [Solution] The system includes a first pulley 21 attached to the output shaft 14 of the engine 2 and a second pulley 22 attached to the input / output shaft 15 of the motor generator 3. The transmission belt 6 is attached to the first pulley 21 and the second pulley 22 such that its inner surface contacts the first pulley 21 and the second pulley 22. Tension pulleys 25, 31, and 32 are provided to contact the outer surface of the transmission belt 6 and press the outer surface toward the inner surface. The transmission belt 6 is made of an elastic material and has a smooth outer surface.

Description

Technical Field

[0001] The present invention relates to a hybrid type power unit and a work vehicle equipped with the power unit.

Background Art

[0002] In a work vehicle equipped with an engine, it is conceivable to mount a hybrid type power unit including the engine and a motor generator by adding a motor generator. In this case, a transmission belt is attached across the pulley of the engine and the pulley of the motor generator, and a tension pulley is configured to contact the outer surface of the transmission belt and press the outer surface toward the inner surface. The power of the engine is transmitted to the motor generator via the transmission belt, and the power of the motor generator is transmitted to the engine via the transmission belt.

[0003] As a transmission belt attached across the pulley of the engine and the pulley of the motor generator, there is a transmission belt disclosed in Patent Document 1. In Patent Document 1, a transmission belt is formed by a rubber body having a V-shaped cross section in which a core wire is embedded and a cover canvas attached to the surface of the rubber body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a work vehicle, an opening for ventilation to assist in heat dissipation of the engine is provided in a bonnet that covers the engine. Since the work vehicle travels and operates in a work area with a lot of dust and the like, dust may enter the inside of the bonnet from the opening of the bonnet.

[0006] If sand and dust get inside the hood, for example, if sand particles adhere to the outer surface of the transmission belt, and the portion of the transmission belt's outer surface with the sand particles attached reaches the tension pulley and is pressed by the tension pulley, the sand particles may get into the weave of the transmission belt's outer surface (cover canvas). If sand particles become lodged in the weave of the outer surface (cover canvas) of the transmission belt and the transmission belt continues to rotate, it is possible that the tension pulley will be damaged by the sand particles on the outer surface (cover canvas) of the transmission belt, raising concerns that this could lead to wear of the tension pulley.

[0007] The present invention aims to suppress wear on the tension pulley in a power unit in which an engine and a motor generator are connected by a transmission belt, and to provide a work vehicle equipped with a power unit that suppresses wear on the tension pulley. [Means for solving the problem]

[0008] The power unit of the present invention comprises an engine, a motor generator, a first pulley mounted on the output shaft of the engine, a second pulley mounted on the input / output shaft of the motor generator, and a transmission belt. The transmission belt is mounted across the first and second pulleys such that its inner surface contacts the first and second pulleys. A tension pulley is provided that contacts the outer surface of the transmission belt and presses the outer surface toward the inner surface. The power of the engine can be transmitted to the motor generator via the transmission belt, and the power of the motor generator can be transmitted to the engine via the transmission belt. The transmission belt is made of an elastic material, and its outer surface is smooth.

[0009] According to the present invention, when the motor-generator functions as a generator, power from the engine is transmitted to the motor-generator via a transmission belt. When the motor-generator functions as a motor, power from the motor-generator is transmitted to the engine via a transmission belt. According to the present invention, a tension pulley is provided that contacts the outer surface of the transmission belt and presses the outer surface toward the inner surface. The transmission belt is formed of an elastic material, the outer surface of the transmission belt is a smooth surface, and there are no joints on the outer surface of the transmission belt.

[0010] As a result, even if, for example, sand particles adhere to the outer surface of the transmission belt, and the portion of the transmission belt's outer surface with the sand particles attached reaches the tension pulley and is pressed by the tension pulley, there are no joints on the outer surface of the transmission belt, so the sand particles will not get stuck in any joints on the outer surface of the transmission belt. If the sand particles do not get stuck in any joints on the outer surface of the transmission belt, they will detach from the outer surface of the transmission belt as the belt rotates.

[0011] Since the transmission belt is mounted across the first pulley of the engine and the second pulley of the motor generator and rotates, the outer surface of the transmission belt repeatedly expands and contracts along the direction of rotation. This promotes the removal of sand particles that have adhered to the outer surface of the transmission belt.

[0012] As described above, according to the present invention, in a power unit in which an engine and a motor generator are connected by a transmission belt, it is possible to avoid the condition in which sand grains continue to adhere to the outer surface of the transmission belt, and wear of the tension pulley can be suppressed, thereby improving the durability of the power unit.

[0013] In the present invention, it is preferable that at least the outer surface of the transmission belt is made of rubber or a similar material.

[0014] According to the present invention, since at least the outer surface of the transmission belt is formed of rubber, it is easy to make the outer surface of the transmission belt a smooth surface, thereby reducing the production costs of the power unit and the transmission belt.

[0015] In the present invention, the tension pulley can be made of metal.

[0016] According to the present invention, even if the detachment of sand grains from the outer surface of the transmission belt is delayed and the tension pulley repeatedly presses against the sand grains on the outer surface of the transmission belt, wear of the tension pulley can be avoided, which is advantageous in terms of improving the durability of the power unit.

[0017] In the present invention, the tension pulley can be formed from a synthetic resin.

[0018] According to the present invention, the tension pulley can be made lighter, and the overall weight of the power unit can be reduced.

[0019] In the present invention, the tension pulley comprises a first tension pulley that presses the outer surface of the portion of the transmission belt that extends to one side from the second pulley, and a second tension pulley that presses the outer surface of the portion of the transmission belt that extends to the other side from the second pulley, and is provided with a biasing member that biases the first tension pulley and the second tension pulley in a direction that brings them closer to each other, and preferably the first tension pulley and the second tension pulley are movable in a first direction in which the first tension pulley presses the outer surface of the transmission belt toward the inner surface, and in a second direction in which the second tension pulley presses the outer surface of the transmission belt toward the inner surface, in accordance with the tension generated in the transmission belt.

[0020] According to the present invention, the first tension pulley and the second tension pulley move in a first direction in which the first tension pulley presses the outer surface of the transmission belt toward the inner surface, and in a second direction in which the second tension pulley presses the outer surface of the transmission belt toward the inner surface. In this case, a biasing member for biasing the first tension pulley and the second tension pulley in a direction in which they approach each other is provided.

[0021] When the power of the engine is transmitted to the motor generator via the transmission belt, if a large tension is generated in the portion of the transmission belt extending from the second pulley to one side, the tension in the portion of the transmission belt extending from the second pulley to the other side becomes small.

[0022] In such a state, the first tension pulley moves in a direction away from the outer surface of the transmission belt due to the large tension. The second tension pulley moves in the second direction along with the movement of the first tension pulley due to the biasing force of the biasing member, and presses the portion of the transmission belt extending from the second pulley to the other side. Thereby, the tension of the transmission belt is maintained in a state suitable for the state in which the power of the engine is transmitted to the motor generator via the transmission belt.

[0023] When the power of the motor generator is transmitted to the engine via the transmission belt, if a large tension is generated in the portion of the transmission belt extending from the second pulley to the other side, the tension in the portion of the transmission belt extending from the second pulley to one side becomes small.

[0024] In such a state, the second tension pulley moves in a direction away from the outer surface of the transmission belt due to the large tension. The first tension pulley moves in the first direction along with the movement of the second tension pulley due to the biasing force of the biasing member, and presses the portion of the transmission belt extending from the second pulley to one side. Thereby, the tension of the transmission belt is maintained in a state suitable for the state in which the power of the motor generator is transmitted to the engine via the transmission belt.

[0025] As described above, according to the present invention, in both the state where the motor generator functions as a generator and the state where the motor generator functions as a motor, the tension of the transmission belt is maintained in an appropriate state, so that the operating stability of the engine and the motor generator can be improved.

[0026] The work vehicle of the present invention is equipped with the power unit according to any one of claims 1 to 4.

[0027] According to the present invention, in a power unit in which an engine and a motor generator are connected by a transmission belt, a work vehicle equipped with a highly durable power unit in which wear of a tension pulley is suppressed can be obtained.

Brief Description of the Drawings

[0028] [Figure 1] It is a plan view of the power unit. [Figure 2] It is a left side view of the power unit. [Figure 3] It is a front view of the power unit. [Figure 4] It is a front view of the vicinity of the input / output shaft, support member, and tension pulley of the motor generator. [Figure 5] It is a cross-sectional view of the pulley, tension pulley, and transmission belt. [Figure 6] It is a front view of the vicinity of the transmission belt in the state where the motor generator functions as a generator. [Figure 7] It is a front view of the vicinity of the transmission belt in the state where the motor generator functions as a motor. [Figure 8] It is a right side view of the tractor.

Mode for Carrying Out the Invention

[0029] Power unit 1 is shown in Figures 1 to 7, and an example of a work vehicle equipped with power unit 1 shown in Figures 1 to 7, a tractor, is shown in Figure 8. In Figures 1 to 8, F indicates the forward direction, B indicates the rear direction, U indicates the upward direction, D indicates the downward direction, R indicates the right direction, and L indicates the left direction.

[0030] (Overall configuration of the power unit) As shown in Figures 1, 2, and 3, the power unit 1 includes an engine 2, a motor generator 3, a turbocharger 4, a DPF 5 (Diesel-particulate-filter), and a transmission belt 6.

[0031] Engine 2 is a four-cylinder inline diesel engine comprising a crankcase 10, cylinders 11, cylinder head 12, cooling fan 13, coolant pump (not shown), etc. A turbocharger 4 is located on the upper left side of the cylinder head 12. A DPF 5 is located on the upper rear side of the cylinder head 12.

[0032] The motor generator 3 is located on the upper right side of the front of the cylinder 11. In the engine 2, the position where the motor generator 3 is mounted is the same position where the alternator (not shown) is mounted.

[0033] (Configuration of the transmission belt 6) As shown in Figures 1, 2, and 3, the output shaft 14 is provided in the crankcase 10, and a pulley 21 is attached to the end of the output shaft 14 that extends forward from the front of the crankcase 10.

[0034] A pulley 22 is attached to the input / output shaft 15 of the motor generator 3. A pulley 23 is mounted on the upper front of the cylinder 11 so as to be rotatable around an axis along the front-rear direction. A cooling fan 13 is attached to the pulley 23, and the pulley 23 drives a cooling water pump.

[0035] A pulley 24 is provided on the lower right side of the front of the crankcase 10 so as to be rotatable around an axis along the front-rear direction. A tension pulley 25 is provided on the right side of the front of the cylinder 11 so as to be rotatable around an axis along the front-rear direction.

[0036] Pulleys 21-24 are made of metal. As shown in Figure 5, multiple protrusions 26 and multiple recesses 27 are formed on the outer surface of pulleys 21-24 around their entire circumference. The tension pulley 25 is made of metal. The outer surface 34 of the tension pulley 25 is formed as a smooth surface around its entire circumference.

[0037] As shown in Figures 1, 2, and 3, a transmission belt 6 is provided. The transmission belt 6 is mounted across pulley 21, pulley 23, pulley 22, pulley 24, tension pulley 25, and tension pulleys 31 and 32, which will be described later. The transmission belt 6 is rotated clockwise in Figure 3 by pulley 21 or pulley 22.

[0038] (Configuration of tension pulleys 31 and 32 attached to the input / output shafts 15 of the motor generator 3) As shown in Figure 4, the first arm 28 is mounted on the input / output shaft 15 of the motor generator 3 so as to be freely swingable. The second arm 29 is mounted on the input / output shaft 15 of the motor generator 3 so as to be freely swingable. The first arm 28 and the second arm 29 can swing independently of each other.

[0039] A tension pulley 31 is rotatably mounted on the first arm 28. A tension pulley 32 is rotatably mounted on the second arm 29. The tension pulleys 31 and 32 are made of synthetic resin. As shown in Figure 5, the outer surface 34 of the tension pulleys 31 and 32 is formed as a smooth surface around its entire circumference.

[0040] As shown in Figure 4, a biasing member 33 is provided, which is a long, slender, flat plate spring formed in an arc shape, and the biasing member 33 is attached across the first arm 28 and the second arm 29. The biasing member 33 biases the first arm 28 (tension pulley 31) and the second arm 29 (tension pulley 32) in a direction that brings the tension pulleys 31 and 32 closer together.

[0041] The tension pulleys 31, 32 and the biasing member 33 swing in a first direction A1 and a second direction A2 around the input / output shaft 15 of the motor generator 3, depending on the tension of the transmission belt 6.

[0042] As the tension of the transmission belt 6 causes the first arm 28 (tension pulley 31) and the second arm 29 (tension pulley 32) to separate, and the distance W1 between the tension pulleys 31 and 32 increases, the biasing force of the biasing member 33 attempts to return the distance W1 between the tension pulleys 31 and 32 to its original position. The distance W1 between the tension pulleys 31 and 32 is maintained within a predetermined range by the biasing member 33.

[0043] As shown in Figures 6 and 7, the first direction A1 is the direction in which the tension pulley 31 presses the outer surface 7c of the transmission belt 6 toward the inner surface (convex portion 7a and concave portion 7b). The second direction A2 is the direction in which the tension pulley 32 presses the outer surface 7c of the transmission belt 6 toward the inner surface (convex portion 7a and concave portion 7b).

[0044] (Configuration of transmission belt 6) As shown in Figure 5, the transmission belt 6 has a main body 7 and a core wire 8 and is formed as a V-ribbed belt.

[0045] The main body 7 is integrally formed from a rubber material such as rubber or polyurethane. Multiple flexible core wires 8, such as wires, are embedded inside the main body 7 and are evenly arranged along the width direction of the main body 7.

[0046] Multiple protrusions 7a and multiple recesses 7b are formed on the inner surface of the main body 7, extending around the entire circumference in the longitudinal direction of the main body 7. No covering material is adhered to the protrusions 7a and recesses 7b of the main body 7, and the material of the main body 7 is exposed at the protrusions 7a and recesses 7b of the main body 7.

[0047] The outer surface 7c of the main body 7 is formed as a smooth surface along its entire length. No covering material is adhered to the outer surface 7c of the main body 7, and the material of the main body 7 is exposed.

[0048] (Contact state between pulleys 21-24 and tension pulleys 25, 31, 32 and transmission belt 6) As shown in Figures 3 and 5, the convex portion 7a and concave portion 7b of the transmission belt 6 (main body portion 7) each fit into the convex portion 26 and concave portion 27 of the pulleys 21 to 24, respectively, so that the transmission belt 6 (main body portion 7) is in contact with the pulleys 21 to 24.

[0049] The contact length of the transmission belt 6 at pulley 21 is ensured by pulley 23 and tension pulley 25. The contact length of the transmission belt 6 at pulley 22 is ensured by tension pulleys 31 and 32.

[0050] The contact length of the transmission belt 6 at pulley 23 is ensured by pulley 21 and tension pulley 31. The contact length of the transmission belt 6 at pulley 24 is ensured by tension pulleys 25 and 32.

[0051] The outer surface 7c of the transmission belt 6 (main body 7) is in contact with the outer surfaces 34 of the tension pulleys 25, 31, and 32. The tension pulleys 25, 31, and 32 are in contact with the outer surface 7c of the transmission belt 6 (main body 7) and press the outer surface 7c of the transmission belt 6 (main body 7) toward the convex portion 7a and the concave portion 7b.

[0052] (State of the convex portion 7a, concave portion 7b, and outer surface 7c when the transmission belt 6 (main body portion 7) is rotated) As shown in Figures 3 and 5, when the transmission belt 6 is driven to rotate in the clockwise direction in Figure 3, the convex portion 7a and concave portion 7b and the outer surface 7c of the transmission belt 6 (main body portion 7) are in the state described below.

[0053] In the convex portion 7a and concave portion 7b of the transmission belt 6 (main body portion 7), the portion of the transmission belt 6 (main body portion 7) that contacts the pulleys 21-24 is compressed in the longitudinal direction of the transmission belt 6 (main body portion 7) compared to the portion of the transmission belt 6 (main body portion 7) that does not contact the pulleys 21-24 and the tension pulleys 25, 31, 32.

[0054] In the convex portion 7a and concave portion 7b of the transmission belt 6 (main body portion 7), the portion of the transmission belt 6 (main body portion 7) that contacts the tension pulleys 25, 31, and 32 is stretched in the longitudinal direction of the transmission belt 6 (main body portion 7) compared to the portion of the transmission belt 6 (main body portion 7) that does not contact the pulleys 21-24 and the tension pulleys 25, 31, and 32.

[0055] As a result, the convex portion 7a and concave portion 7b of the transmission belt 6 (main body portion 7) repeatedly extend (the portion where the transmission belt 6 (main body portion 7) contacts the tension pulleys 25, 31, and 32) and compress (the portion where the transmission belt 6 (main body portion 7) contacts the pulleys 21 to 24) as the transmission belt 6 (main body portion 7) is rotated.

[0056] As shown in Figures 3 and 5, on the outer surface 7c of the transmission belt 6 (main body 7), the portion of the transmission belt 6 (main body 7) that contacts the tension pulleys 25, 31, and 32 is compressed in the longitudinal direction of the transmission belt 6 (main body 7) compared to the portion of the transmission belt 6 (main body 7) that does not contact the pulleys 21-24 and the tension pulleys 25, 31, and 32.

[0057] On the outer surface 7c of the transmission belt 6 (main body 7), the portion of the transmission belt 6 (main body 7) that contacts the pulleys 21-24 is stretched in the longitudinal direction of the transmission belt 6 (main body 7) compared to the portion of the transmission belt 6 (main body 7) that does not contact the pulleys 21-24 and the tension pulleys 25, 31, 32.

[0058] As a result, the outer surface 7c of the transmission belt 6 (main body 7) repeatedly stretches (the part where the transmission belt 6 (main body 7) contacts the pulleys 21-24) and compresses (the part where the transmission belt 6 (main body 7) contacts the tension pulleys 25, 31, 32) as the transmission belt 6 (main body 7) is rotated.

[0059] (Motor generator 3 is functioning as a generator) As shown in Figure 6, when the motor generator 3 functions as a generator, power from the engine 2 is transmitted from the output shaft 14 and pulley 21 to pulleys 22, 23, and 24 via the transmission belt 6, driving the motor generator 3, cooling fan 13, and cooling water pump. The AC power generated by the motor generator 3 is converted to DC power by an inverter device (not shown) and charged to a battery (not shown).

[0060] Focusing on the portion 6a of the transmission belt 6 extending from pulley 22 toward tension pulley 31 and the portion 6b of the transmission belt 6 extending from pulley 22 toward tension pulley 32, the following conditions are observed.

[0061] When the motor generator 3 functions as a generator, a large tension is generated in section 6a of the transmission belt 6, and the tension in section 6b of the transmission belt 6 becomes smaller than the tension in section 6a of the transmission belt 6.

[0062] When the above state is reached, the tension pulley 31 moves in a direction away from the outer surface 7c (see Figure 5) of the transmission belt 6 (main body 7) (second direction A2) due to the large tension in portion 6a of the transmission belt 6. The tension pulley 32 moves in the second direction A2 via the biasing member 33 as the tension pulley 31 moves, and presses the outer surface 7c of portion 6b of the transmission belt 6 (main body 7) toward its inner surface (see convex portion 7a and concave portion 7b in Figure 5). This maintains the tension of the transmission belt 6 in a state suitable for the power of the engine 2 being transmitted to the motor generator 3 via the transmission belt 6.

[0063] (The motor generator 3 is functioning as a motor.) As shown in Figure 7, when the motor generator 3 functions as a motor, the DC power from the battery is converted into AC power by the inverter device and supplied to the motor generator 3, causing the motor generator 3 to operate as a motor.

[0064] The power from the motor-generator 3 is transmitted from the input / output shaft 15 and pulley 22 to pulleys 23 and 24 via the transmission belt 6, driving the cooling fan 13 and the cooling water pump. The power from the motor-generator 3 is transmitted to the output shaft 14 via pulley 21, and the power from the engine 2 and the power from the motor-generator 3 are combined and output from the output shaft 14 of the engine 2.

[0065] When the motor generator 3 functions as a motor, a large tension is generated in section 6b of the transmission belt 6, and the tension in section 6a of the transmission belt 6 becomes smaller than the tension in section 6b of the transmission belt 6.

[0066] When the above state is reached, the tension pulley 32 moves in a direction away from the outer surface 7c (see Figure 5) of the transmission belt 6 (main body 7) (first direction A1) due to the large tension in portion 6b of the transmission belt 6. The tension pulley 31 moves in the first direction A1 via the biasing member 33 as the tension pulley 32 moves, pressing the outer surface 7c (see Figure 5) of portion 6a of the transmission belt 6 (main body 7) toward its inner surface (see convex portion 7a and concave portion 7b in Figure 5). This maintains the tension of the transmission belt 6 in a state suitable for the power of the motor generator 3 to be transmitted to the engine 2 via the transmission belt 6.

[0067] (Tractor configuration) Figure 8 shows a tractor equipped with power unit 1. The front frame 43 is connected to the engine 2 and extends forward. The transmission case 44 is connected to the rear of the engine 2, and the transmission case 45 is connected to the rear of the transmission case 44. The engine 2, front frame 43, transmission case 44, and transmission case 45, etc., constitute the airframe 40.

[0068] The front axle case 46 is attached to the front frame 43, and the right and left front wheels 41 are attached to the front axle case 46. The right and left rear wheels 42 are attached to the rear of the transmission case 45. The front wheels 41 and rear wheels 42 support the body 40.

[0069] Power from the power unit 1 is transmitted from the output shaft 14 (see Figure 3) of the engine 2 to the transmission unit (not shown) inside the transmission case 45 via the transmission shaft (not shown) inside the transmission case 44, and then transmitted from the transmission unit to the rear wheels 42, driving the rear wheels 42. Power branched from the transmission unit is transmitted via the transmission shaft 47 to the differential unit (not shown) inside the front axle case 46, and then transmitted from the differential unit to the front wheels 41, driving the front wheels 41.

[0070] A radiator 48 is mounted on the front frame 43, and a bonnet 49 is provided to cover the power unit 1 and the radiator 48. A front grille 50 is provided on the front of the bonnet 49, and side grilles 51 are provided on the right and left sides of the bonnet 49.

[0071] Coolant is circulated between the engine 2 and the radiator 48 by a coolant pump, cooling the engine 2. A cooling fan 13 (see Figures 1, 2, and 3) brings outside air into the bonnet 49 through the front grille 50 and side grilles 51, and supplies it to the radiator 48 and the engine 2.

[0072] The lower part of the bonnet 49 (the lower part of the power unit 1) is open downwards. In addition to the front grille 50 and side grilles 51, several small ventilation openings (not shown) are provided in the bonnet 49.

[0073] A steering wheel 53 for steering the driver's seat 52 and the front wheel 41 is provided on the aircraft body 40. The lops frame 54 is connected to the mission case 45 and extends upward beyond the driver's seat 52.

[0074] A top link 55 is mounted on the upper rear of the transmission case 45 so as to be able to swing up and down. Right and left lower links 56 are mounted on the lower rear of the transmission case 45 so as to be able to swing up and down. Right and left lift arms 57 are provided on the lower rear of the transmission case 45, and a rod 58 is connected to the lift arms 57 and the lower links 56.

[0075] Working devices such as a rotary tiller (not shown) and a plow (not shown) are attached to the top link 55 and the lower link 56. The working devices are raised and lowered via the top link 55 and the lower link 56 by the up-and-down swinging drive of the lift arm 57.

[0076] The PTO shaft 59 is located at the rear of the transmission case 45, and power from the power unit 1 is transmitted to the PTO shaft 59 via the transmission case 44 and a transmission shaft (not shown) inside the transmission case 45. A transmission shaft (not shown) is connected between the working device attached to the top link 55 and the lower link 56 and the PTO shaft 59, thereby transmitting power from the PTO shaft 59 to the working device and driving the working device.

[0077] (First alternative embodiment of the invention) The transmission belt 6 may be formed as a V-belt instead of a V-ribbed belt, or it may be configured as a toothed belt (timing belt). In the above-described configuration, multiple transmission belts 6 may be provided. Cover canvas (not shown) may be attached to the inner surface of the transmission belts 6, and the configuration may be such that cover canvas is not attached to the outer surface 7c of the transmission belts 6.

[0078] (Second alternative embodiment of the invention) The cylinder 11 of engine 2 may be configured as an inline 3-cylinder type, an inline 6-cylinder type, a V6 type, a V8 type, etc. Engine 2 does not have to be a diesel engine; it may be a gasoline engine or a hydrogen engine that uses hydrogen as fuel. Engine 2 may also be one that does not have a turbocharger 4.

[0079] (Third alternative embodiment of the invention) The motor generator 3 may not be directly attached to the engine 2, but rather a support frame (not shown) may be connected to the engine 2 and extend outward, with the motor generator 3 being attached to the support frame. Multiple motor generators 3 may be provided in the power unit 1.

[0080] (Fourth alternative embodiment of the invention) If the motor generator 3 is mounted in the same location where the alternator would normally be mounted, a dedicated mounting base (not shown) for mounting the motor generator 3 may be provided on the engine 2. Alternatively, the motor generator 3 may be mounted on a mounting base (not shown) intended for mounting the alternator.

[0081] (Fifth alternative embodiment of the invention) The tension pulleys 31 and 32 may be made of metal. Instead of the leaf spring biasing member 33, a coil spring (not shown) may be provided as the biasing member 33.

[0082] In the above configuration, a biasing member 33 is attached across the end of the first arm 28 and the end of the second arm 29, and the first arm 28 (tension pulley 31) and the second arm 29 (tension pulley 32) are biased in a direction that brings the tension pulley 31 and tension pulley 32 closer to each other by the contraction of the biasing member 33.

[0083] (Sixth alternative embodiment of the invention) The tension pulley 25 may be made of synthetic resin. All of the tension pulleys 25, 31, and 32 may be made of metal, or they may all be made of synthetic resin. The tension pulley 25 may be made of synthetic resin, while the tension pulleys 31 and 32 may be made of metal.

[0084] The combination of tension pulleys 25, 31, and 32, in which some are made of metal and the remaining ones are made of synthetic resin, can be changed according to the characteristics of the power unit 1.

[0085] (Seventh alternative embodiment of the invention) The power unit 1 may be mounted not only on tractors, but also on agricultural work vehicles such as combine harvesters, or construction work vehicles such as backhoes and wheel loaders. The power unit 1 may be used not as a mobile work vehicle, but as a power source to drive work equipment installed inside the building, such as a generator, pump, or compressor.

[0086] (Correspondence between parts) - 1 Pulley 21 corresponds to the first pulley. Pulley 22 corresponds to the second pulley. The protrusions 7a and recesses 7b of the main body 7 of the transmission belt 6 correspond to the inner surface of the transmission belt 6. Part 6a of the transmission belt 6 corresponds to the portion of the transmission belt 6 that extends from the second pulley (pulley 22) to one side. Part 6b of the transmission belt 6 corresponds to the portion of the transmission belt 6 that extends from the second pulley (pulley 22) to the other side. Tension pulley 31 corresponds to the first tension pulley. Tension pulley 32 corresponds to the second tension pulley.

[0087] (Correspondence between parts) - 2 It is equipped with engine 2 and motor generator 3. The motor generator 3 is equipped with a first pulley (pulley 21) attached to the output shaft 14 of the engine 2, and a second pulley (pulley 22) attached to the input / output shaft 15 of the motor generator 3.

[0088] A transmission belt 6 is provided, and the transmission belt 6 is mounted across the first pulley (pulley 21) and the second pulley (pulley 22) such that the inner surface of the transmission belt 6 (convex portion 7a, concave portion 7b) contacts the first pulley (pulley 21) and the second pulley (pulley 22).

[0089] The transmission belt 6 is equipped with tension pulleys 25, 31, and 32 that contact the outer surface 7c and press the outer surface 7c toward the inner surface (convex portion 7a, concave portion 7b). The power of engine 2 can be transmitted to motor generator 3 via transmission belt 6, and the power of motor generator 3 can be transmitted to engine 2 via transmission belt 6. The transmission belt 6 is formed from an elastic material, and the outer surface 7c of the transmission belt 6 is a smooth surface.

[0090] (Correspondence between parts) - 3 At least the outer surface 7c of the transmission belt 6 is made of rubber or a similar material.

[0091] (Correspondence between parts) - 4 The tension pulleys 31 and 32 each include a first tension pulley that presses against the outer surface 7c of the portion of the transmission belt 6 that extends from the second pulley (pulley 22) to one side, and a second tension pulley that presses against the outer surface 7c of the portion of the transmission belt 6 that extends from the second pulley (pulley 22) to the other side.

[0092] A biasing member 33 is provided that biases the first tension pulley (tension pulley 31) and the second tension pulley (tension pulley 32) in a direction that brings them closer together.

[0093] In accordance with the tension generated in the transmission belt 6, the first tension pulley (tension pulley 31) and the second tension pulley (tension pulley 32) are movable in a first direction A1 in which the first tension pulley (tension pulley 31) presses the outer surface 7c of the transmission belt 6 toward the inner surface (convex portion 7a, concave portion 7b), and in a second direction A2 in which the second tension pulley (tension pulley 32) presses the outer surface 7c of the transmission belt 6 toward the inner surface (convex portion 7a, concave portion 7b).

[0094] The work vehicle is equipped with the aforementioned power unit 1. [Industrial applicability]

[0095] The present invention can be applied not only to power units 1 mounted on work vehicles, but also to stationary power units 1 that drive generators, pumps, etc. This invention can be applied not only to tractors but also to agricultural work vehicles such as combine harvesters, and to construction work vehicles such as backhoes and wheel loaders. [Explanation of Symbols]

[0096] 2 engines 3 Motor Generator 6. Transmission belt 6a part 6b part 7a Convex part (inner surface) 7c recess (inner surface) 7c Exterior 14 Output shaft 15 Input / Output Axes 21 Pulley (1st pulley) 22 Pulley (2nd pulley) 25 Tension Pulley 30 Support member 31. Tension pulley (first tension pulley) 32. Tension pulley (2nd tension pulley) 33. Biasing member A1 1st direction A2 2nd direction

Claims

1. The engine and Motor generator and, A first pulley attached to the output shaft of the aforementioned engine, A second pulley attached to the input / output shaft of the motor generator, It is equipped with a transmission belt, The transmission belt is mounted across the first pulley and the second pulley such that its inner surface contacts the first pulley and the second pulley. A tension pulley is provided that contacts the outer surface of the transmission belt and presses the outer surface toward the inner surface, The power of the engine can be transmitted to the motor generator via the transmission belt, and the power of the motor generator can be transmitted to the engine via the transmission belt. A power unit in which the transmission belt is formed of an elastic member and the outer surface of the transmission belt is a smooth surface.

2. The power unit according to claim 1, wherein at least the outer surface of the transmission belt is formed of rubber or rubber.

3. The power unit according to claim 1, wherein the tension pulley is formed of metal.

4. The power unit according to claim 1, wherein the tension pulley is formed of synthetic resin.

5. The tension pulley comprises a first tension pulley that presses against the outer surface of the portion of the transmission belt that extends from the second pulley to one side, and a second tension pulley that presses against the outer surface of the portion of the transmission belt that extends from the second pulley to the other side. A biasing member is provided to bias the first tension pulley and the second tension pulley in a direction that brings them closer together. The power unit according to claim 1, wherein the first tension pulley and the second tension pulley are movable in a first direction in which the first tension pulley presses the outer surface of the transmission belt toward the inner surface, and in a second direction in which the second tension pulley presses the outer surface of the transmission belt toward the inner surface, in accordance with the tension generated in the transmission belt.

6. A work vehicle equipped with the power unit described in any one of claims 1 to 5.

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