Power transmission systems and construction machinery

Abstract

To provide a power transmission system and a construction machine capable of being improved in impact resistance.SOLUTION: A power transmission system 10 includes: at least one set (for example, three sets) of dynamo-electric machines 21, a speed reducer 23, and a damper 25. An input portion of the speed reducer 23 is connected to an output portion of the dynamo-electric machine 21, The speed reducer 23 is a gear mechanism having a plurality of gears meshed with each other and having a backlash. The damper 25 is connected between a fixing portion of the speed reducer 23 or a member connected to the fixing portion, and an output portion of the speed reducer 23 or a member connected to the output portion. The damper 25 reduces a load acting in the backlash disposed between the output portion outputting power in the speed reducer 23 and the fixing portion supporting the output portion. The damper 25 generates reduction force changed with increasing tendency in accompany with increase in speed of a movable portion caused by the load acting in the backlash.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power transmission system and a construction machine. [Background technology]

[0002] BACKGROUND ART Conventionally, there is known a reducer that includes a damper made of an elastic material between a power transmission part and an output part (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-7555 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a reducer and an electric motor as in the above-mentioned conventional technology are mounted as a drive device on the arm or boom of a construction machine, there is a possibility that the reducer will not be able to properly absorb impacts input from outside due to insufficient material strength of the damper.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a power transmission system and a construction machine that are capable of improving impact resistance. [Means for solving the problem]

[0006] A power transmission system according to one aspect of the present invention includes a gear mechanism having a plurality of gears that mesh with each other and have backlash, and a load that reduces a load acting within the backlash.

[0007] With this configuration, the load acting on the gear mechanism during backlash can be reduced by the load, which improves the shock resistance of the gear mechanism compared to a case where no load is provided.

[0008] In the above configuration, the load may be a damper that generates a reducing force that changes with an increasing tendency as the speed of the movable part due to the load in the backlash increases.

[0009] In the above configuration, the load may reduce the load acting in the backlash provided between an output part that outputs power by the gear mechanism and a fixed part that supports the output part.

[0010] A power transmission system according to another aspect of the present invention includes a reducer having a plurality of gears that mesh with each other and have backlash, and a damper that generates a reduction force that increases as the speed of a moving part increases due to a load acting within the backlash.

[0011] With this configuration, the load acting in the backlash of the reducer can be reduced by the damper, which can improve the impact resistance of the reducer compared to a case where no damper is provided.

[0012] A construction machine according to another aspect of the present invention comprises a main body, a boom connected to the main body, an arm connected to the boom, an attachment connected to the arm, a power transmission system provided at at least one of the connection parts between the main body and the boom, the connection part between the boom and the arm, and the connection part between the arm and the attachment, and a rotating electric machine that outputs power to the power transmission system, wherein the power transmission system comprises a reducer having a plurality of gears that mesh with each other and have backlash, and a damper that generates a reduction force that increases as the speed of the moving part increases due to the load acting within the backlash.

[0013] With this configuration, each part of the construction machine can be driven by the power output from the rotating electric machine. Furthermore, even if an impact load is applied to each part, the impact load acting in the backlash can be reduced, thereby improving impact resistance. [Effects of the Invention]

[0014] According to the present invention, by providing a load that reduces the load acting in the backlash of the gear mechanism, it is possible to improve the shock resistance of the gear mechanism. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram showing a construction machine equipped with a power transmission system according to an embodiment of the present invention. [Figure 2] 2 is a perspective view showing a part of a reducer of the power transmission system shown in FIG. 1 in a cutaway view. [Figure 3] FIG. 2 is an enlarged view of a portion of the power transmission system shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a power transmission system and a construction machine according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0017] <Construction machinery> FIG. 1 is a diagram showing a construction machine 1 equipped with a power transmission system 10 according to an embodiment. As shown in FIG. 1, the construction machine 1 is, for example, a type of excavator, known as a power shovel. The construction machine 1 comprises a main body 3 having a swivel section 3a and a traveling section 3b, a boom 5 connected to the main body 3, an arm 7 connected to the boom 5, a bucket (an example of an attachment in the claims) 9 connected to the arm 7, and a power transmission system 10.

[0018] <Power transmission system> The power transmission system 10 includes at least one set (for example, three sets) of rotating electric machines 21, reducers 23, and dampers 25. For example, the three sets of rotating electric machines 21, reducers 23, and dampers 25 are a first rotating electric machine 21a, a first reducer 23a, and a first damper 25a, a second rotating electric machine 21b, a second reducer 23b, and a second damper 25b, and a third rotating electric machine 21c, a third reducer 23c, and a third damper 25c.

[0019] <Reducer> The reducer 23 is a gear mechanism having a plurality of gears that mesh with each other and have backlash, and is, for example, an eccentric oscillating gear transmission. The input portion of the reducer 23 is connected to the output portion of the rotating electric machine 21. The reducer 23, for example, reduces the rotational speed of the power input to the input portion from the rotating electric machine 21, and outputs the reduced power from the output portion. Backlash of the reducer 23 is provided at least between the fixed portion and the output portion of the reducer 23. The fixed portion of the reducer 23 is, for example, a case that houses multiple gears of the reducer 23, and is fixed to the case of the rotating electric machine 21.

[0020] FIG. 2 is a perspective view showing a part of the reducer 23 of the power transmission system 10 shown in FIG. 1 in a cutaway manner. As shown in Figure 2, the reducer 23 includes, for example, a case 31 which is a fixed part, a carrier 33 which is an output part, an input gear 35 which is an input part, a plurality of transmission gears 37, a plurality of crankshafts 39, a first oscillating gear 41 and a second oscillating gear 43. The case 31 is fixed to, for example, the case of the rotating electrical machine 21. The inner circumferential surface of the case 31 is provided with an internal tooth portion in which a plurality of pin grooves are formed to hold a plurality of internal tooth pins 31a. The carrier 33 is connected to a driven part (not shown). The carrier 33 supports a crankshaft 39, a first oscillating gear 41, and a second oscillating gear 43. The input gear 35 is connected to the output portion of the rotating electrical machine 21 .

[0021] A plurality of (for example, three) transmission gears 37 mesh with the input gear 35. The plurality of transmission gears 37 are connected to a crankshaft 39 by spline coupling or the like. The plurality of (e.g., three) crankshafts 39 include a shaft portion 39a supported by the carrier 33 and two eccentric portions 39b provided on the shaft portion 39a. The two eccentric portions 39b of each crankshaft 39 are inserted into through holes formed in the first oscillating gear 41 and the second oscillating gear 43.

[0022] The outer circumferential surfaces of the first oscillating gear 41 and the second oscillating gear 43 are provided with external teeth that mesh with a plurality of internally toothed pins 31a of the internally toothed portion of the case 31. The first oscillating gear 41 and the second oscillating gear 43 move eccentrically together with the eccentric portion 39b in accordance with the rotation of each crankshaft 39 that receives the rotational driving force of the input gear 35. As a result, the first oscillating gear 41 and the second oscillating gear 43 oscillate and rotate while their external teeth mesh with some of the multiple internally toothed pins 31a of the case 31, and rotate together with the carrier 33 around the axis O relative to the case 31.

[0023] The backlash of the reducer 23 is, for example, the angular range (hereinafter simply referred to as the angular range) of the gap within which the carrier 33 can rotate about the axis O when rotation is applied to the carrier 33 with the input gear 35 fixed. The backlash of the reducer 23 is, for example, the sum of the backlashes of the spline couplings between the input gear 35 and the multiple transmission gears 37, between the external teeth of each of the oscillating gears 41, 42 and the internal teeth of the case 31, and between the transmission gear 37 and the crankshaft 39. The backlash includes the above-mentioned angular range that has changed from the above-mentioned angular range in the state at the time of product shipment, including the backlash becoming larger than the value at the time of product shipment due to changes over time.

[0024] <Damper> The damper 25 is a load that reduces the load acting in the backlash of the reducer 23. The load acting in the backlash is a load that acts between a fixed portion of the reducer 23 or a member connected to the fixed portion and an output portion of the reducer or a member connected to the output portion while each gear (e.g., the input gear 35, the multiple transmission gears 37, the oscillating gears 41 and 42, the transmission gear 37, and the crankshaft 39) that forms backlash in the above-mentioned angular range is rotating. Specific examples of the fixed portion of the reducer 23, the member connected to the fixed portion, the output portion of the reducer, and the member connected to the output portion will be described later.

[0025] The damper 25 generates a reduction force that increases as the speed of the moving part caused by the load increases. The damper may be, for example, a rotary damper or an expandable cylinder damper, and generates the reduction force by the fluid resistance of a gas such as air or a liquid such as oil. The damper 25 generates a reduction force that is proportional to, for example, the speed of the moving part (for example, a cylinder or rotor) caused by the load or the square of the speed. The damper 25 is connected between the fixed part of the reducer 23 or a member connected to the fixed part, and the output part of the reducer 23 or a member connected to the output part. The damper 25 reduces the load acting in the backlash provided between the fixed part and the output part of the reducer 23.

[0026] For example, if a larger load in the opposite direction is input to the output section while the reducer 23 is outputting power from the output section after reducing the speed according to the power input from the rotating electric machine 21, this load will cause the movable member to be displaced in the opposite direction in the backlash of the reducer 23. The displacement of the movable member in the opposite direction is, for example, the reverse rotation of the gear on the output section side of two gears that mesh with each other. The speed of the movable member displaced in the opposite direction in the backlash (i.e., the side where a gap or play is provided by the backlash) will increase rapidly. Damper 25 restricts the increase in speed when the speed of the movable member increases in backlash due to the load input from the output side of reducer 23, causing an impact. As a result, damper 25 increases the duration of the force and reduces the magnitude of the force without changing the total amount of impulse.

[0027] The damper 25 transmits a portion of the power of the rotating electric machine 21 input from the input portion of the reducer 23 in the backlash, thereby reducing the total amount of impulse and alleviating the load of the power acting on the reducer 23.

[0028] As shown in FIG. 1, the first rotating electric machine 21a, the first reducer 23a, and the first damper 25a are disposed at the connection between the main body 3 and the boom 5. For example, a case accommodating the first rotating electric machine 21a and the first reducer 23a is fixed to a support portion 3c provided on the main body 3. An output portion of the first reducer 23a is connected to the boom 5. The first reducer 23a rotates the boom 5 using power generated from the first rotating electric machine 21a.

[0029] The first damper 25a is connected between the support part 3c of the main body 3 and the boom 5. The first damper 25a reduces a load (such as an impact load input to the boom 5) acting in a backlash provided between the fixed part and the output part of the first reducer 23a.

[0030] The second rotating electric machine 21b, the second reducer 23b, and the second damper 25b are disposed at the connection between the boom 5 and the arm 7. For example, a case accommodating the second rotating electric machine 21b and the second reducer 23b is fixed to the boom 5. The output portion of the second reducer 23b is connected to the arm 7. The second reducer 23b rotationally drives the arm 7 by power generated from the second rotating electric machine 21b.

[0031] The second damper 25b is connected between the boom 5 and the arm 7. The second damper 25b reduces a load (such as an impact load input to the arm 7) acting in a backlash provided between the fixed portion and the output portion of the second reducer 23b.

[0032] The third rotating electric machine 21c, the third reducer 23c, and the third damper 25c are disposed at a connection between the arm 7 and the bucket 9. For example, a case that houses the third rotating electric machine 21c and the third reducer 23c is fixed to the arm 7. The output portion of the third reducer 23c is connected to the bucket 9. The third reducer 23c rotates and drives the bucket 9 by power generated from the third rotating electric machine 21c.

[0033] The third damper 25c is connected between the arm 7 and the bucket 9. The third damper 25c reduces a load (such as an impact load input to the bucket 9) acting in a backlash provided between the fixed portion and the output portion of the third reducer 23c.

[0034] FIG. 3 is an enlarged view of a portion of the power transmission system 10 shown in FIG. As shown in Figure 3, the backlash B provided in the second reducer 23b is, for example, the angle range in which the arm 7 can rotate in the reverse direction when a load acts on the arm 7, which rotates by the power of the second rotating electric machine 21b, in the direction opposite to the rotation direction, or the angle range in which the arm 7 can rotate when a load acts on the arm 7 with zero input from the second rotating electric machine 21b.

[0035] The second damper 25b connected between the boom 5 and the arm 7 generates a reduction force that tends to increase as the speed of the movable part 27 of the second damper 25b increases due to the load acting between the backlash B of the second reducer 23b. Here, the backlash of the reducer 23 at the time of product shipment is, for example, a value within a certain range defined by a certain lower limit value and an upper limit value. The certain lower limit value is, for example, a value required to ensure the desired impact reduction by the damper 25. The certain lower limit value is, for example, about 10 to 15 [arc·min]. The certain upper limit value is, for example, a value required to ensure the desired operability of the reducer 23. The certain upper limit value is, for example, about 20 to 30 [arc·min].

[0036] As described above, the power transmission system 10 of the embodiment includes the damper 25 that reduces the load acting in the backlash of the reducer 23. Therefore, the impact resistance of the reducer 23 can be improved compared to, for example, a case where the damper 25 is not provided. In particular, since the damper 25 is connected between the fixed portion of the reducer 23 or a member connected to the fixed portion and the output portion of the reducer 23 or a member connected to the output portion, it can efficiently absorb external impacts by utilizing the backlash of the reducer 23. This makes it possible to further improve the impact resistance of the reducer 23.

[0037] As described above, the construction machine 1 of the embodiment can drive each part of the construction machine 1 using the power output from the rotating electric motor 21, and even if an impact load is input to each part, for example, the impact load acting in the backlash can be reduced, thereby improving impact resistance.

[0038] [Variations] Modifications of the embodiment will be described below. Note that the same parts as those in the above-described embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified.

[0039] In the power transmission system 10 mounted on the construction machine 1 of the above-described embodiment, the damper 25 is arranged outside the reducer 23, but this is not limited to this, and the damper 25 may also be arranged inside the reducer 23.

[0040] In the above-described embodiment, the power transmission system 10 is mounted on the construction machine 1, but this is not limiting. The power transmission system 10 may be mounted on equipment other than the construction machine 1. In this case, the rotating electric machine 21 of the power transmission system 10 may be omitted, or an appropriate gear mechanism may be provided instead of the reducer 23.

[0041] In the above embodiment, the reducer 23 is a so-called eccentric oscillating type reducer 23, and is described as including a case 31 as a fixed part, a carrier 33 as an output part, an input gear 35 as an input part, a plurality of transmission gears 37, a plurality of crankshafts 39, a first oscillating gear 41, and a second oscillating gear 43. However, the eccentric oscillating type reducer is not limited to the above configuration, and it is sufficient if it includes at least one crankshaft 39 and an oscillating gear that is oscillated and rotated by this crankshaft 39.

[0042] For example, a more specific description will be given of an eccentric oscillating type reducer having one crankshaft 39. In this case, the reducer has a so-called center crankshaft as the crankshaft 39, which is coaxial with the axis O. As this center crankshaft rotates, the oscillating gears 41, 42 are oscillated and rotated.

[0043] In the construction machine 1 described above, the bucket 9 is connected to the arm 7 as an example of an attachment, but this is not limiting. Various attachments such as a fork can be used as the attachment.

[0044] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims.

[0045] Among the embodiments disclosed in this specification, those that are comprised of multiple objects may be integrated, and conversely, those that are comprised of a single object may be separated into multiple objects. Regardless of whether they are integrated, it is sufficient that they are configured to achieve the object of the invention. [Explanation of symbols]

[0046] 1. Construction machinery 3...Main unit 5... Boom 7...Arm 9...Bucket (attachment) 10...Power transmission system 21...Rotating electric machine 23...Reduction gear (gear mechanism) 25...Damper (load) 27...Movable part 31...Case (fixed part) 33...Carrier (output section) 35...Input gear (gear, input part) 37...Transmission gear (gear) 39...Crankshaft 41...First oscillating gear (gear) 43...Second oscillating gear (gear)

Claims

1. a gear mechanism having a plurality of gears that mesh with each other and have backlash; a load that reduces the load acting in the backlash, The load is The load acting in the backlash provided between an output part that outputs power by the gear mechanism and a fixed part that supports the output part is reduced. Power transmission system.

2. The load is The damper generates a reducing force that increases as the speed of the movable part increases due to the load in the backlash. The power transmission system of claim 1 .

3. The main body and a boom connected to the main body; an arm connected to the boom; an attachment connected to the arm; a power transmission system provided at at least one of a connection portion between the main body and the boom, a connection portion between the boom and the arm, and a connection portion between the arm and the attachment; a rotating electric machine that outputs power to the power transmission system; Equipped with The power transmission system includes: a reducer having a plurality of gears that mesh with each other and have backlash; a damper that generates a reducing force that increases as the speed of the movable part increases due to a load acting in the backlash; Equipped with Construction machinery.

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