JP2004060505A - Hydraulic working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic working machine whose drive source is changed from an engine to an electric motor capable of suppressing the equipment cost of a power unit and accommodating easily in any existing machine room by suppressing its size likely to become large. <P>SOLUTION: The hydraulic working machine uses the electric motor 31 as the drive source in lieu of the engine, and relation of the maximum discharge capacity B2 of a hydraulic pump 39 driven by the motor 31 to the maximum discharge capacity B1 of the hydraulic pump on the engine drive system is set to B2=B1x(A1/A2), where A1 is the rated engine speed, and A2 is the rated motor speed, and thereby a maximum pump discharge amount approximately the same as on the engine drive system is secured. <P>COPYRIGHT: (C)2004,JPO

Description

【００４１】
このように、両パワーユニット１１，３２は全長において大差はなく、電動機駆動方式におけるパワーユニット３２の全長寸法を機械室１２の幅寸法Ｗ以下に抑えて、機械室１２内に容易に収めることが可能となる。
【００４２】
なお、標準的な電動機は、ストール時に定格トルクの５〜６倍のトルクが作用することから、出力軸もこのような大トルクに耐えうるように直径寸法が定められる。
【００４３】
一方、図２に示すように、電動機右側出力軸３４はカップリング３８に対してキー結合されるが、このキー結合部分４０にも大トルクが作用することを考慮して、標準ではこのキー結合部分４０の長さを長くとるために、その分、出力軸３４が長く設計される。
【００４４】
しかし、油圧ショベルの場合、リリーフ弁の作用によって油圧ポンプ３９には定格トルク以上のトルクは作用しないのが現実である。
【００４５】
そこで、この油圧ショベルにおいては、上記現実に基づき、キー結合のための出力軸３４の長さ寸法Ｌを、結合に必要な最小限の大きさとしている。
【００４６】
これにより、パワーユニット３２の全長がさらに短く抑えられるため、同ユニット３２を機械室１２内に一層容易に収容することができる。
【００４７】
ところで、上記実施形態では油圧ショベルを適用対象として例示したが、本発明は、油圧ショベルを母体として構成される他の作業機械、たとえば図３のアタッチメント７におけるバケット６に代えてクランプを装着した解体機や、アーム５に代えて伸縮腕を装着し、先端にクラムシェルバケットを取付けた深穴掘削機にも上記同様に適用することができる。
【００４８】
【発明の効果】
上記のように本発明によると、駆動源としてエンジンに代えて電動機を用い、この電動機によって駆動される油圧ポンプの最大吐出容量Ｂ２を、エンジン駆動方式における油圧ポンプの最大吐出容量Ｂ１に対して、
Ｂ２＝Ｂ１・（Ａ１／Ａ２）
Ａ１：エンジン定格回転数
Ａ２：電動機定格回転数
の関係に設定したから、駆動源をエンジンから電動機に転換しながら、エンジン駆動方式の場合とほぼ同じポンプ最大吐出量が得られ、機械本来の作業能力をそのまま確保することができる。
【００４９】
しかも、ポンプ最大吐出容量を大きくすることによるポンプの大形化及びコストアップは、インバータや増速機構という別設備を追加する場合よりも格段に小さくてすむ。
【００５０】
従って、パワーユニットの電動機駆動方式への転換に伴う設備コストの高騰を抑え、かつ、占有スペースの増加を最小限に抑えて、既存の機械室に容易に収めることが可能となる。
【図面の簡単な説明】
【図１】本発明の実施形態にかかる油圧ショベルにおけるパワーユニットの背面図である。
【図２】図１の一部拡大断面図である。
【図３】油圧ショベルの全体側面図である。
【図４】従来のエンジン駆動方式によるパワーユニットの背面図である。
【符号の説明】
１２　機械室
３２　パワーユニット
３１　駆動源としての電動機
３９　油圧ポンプ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic work machine such as a hydraulic shovel or a dismantling machine configured by partially changing an attachment with a hydraulic shovel as a base.
[0002]
[Prior art]
A conventional technique will be described using a hydraulic excavator as an example.
[0003]
As shown in FIG. 3, the hydraulic excavator has an upper revolving unit 3 having a cabin 2 mounted on a crawler-type lower traveling unit 1 so as to be pivotable about a vertical axis O. An excavation attachment 7 including a 4, an arm 5, and a bucket 6 is mounted.
[0004]
As the hydraulic actuator, hydraulic cylinders 8, 9, 10 for the boom, the arm, the bucket, and the like are provided in addition to the traveling and turning hydraulic motors (not shown).
[0005]
A hydraulic pump serving as a hydraulic source for supplying pressure oil to each of the actuators and a power unit 11 including an engine serving as a drive source for driving the hydraulic pump are provided in a machine room 12 provided at a rear portion of the upper swing body 2. Installed in the direction (machine width direction).
[0006]
FIG. 4 shows a device arrangement in the power unit 11.
[0007]
In the figure, reference numeral 13 denotes an engine. Output shafts 14 and 15 project from both sides of the engine 13 (left and right as viewed from the back, the same applies to the left and right directions described below), and a coupling 16 is connected to a right output shaft 15. The input shaft 17a of the variable displacement hydraulic pump 17 is connected via the input shaft 17a.
[0008]
On the left side of the engine 13, an oil cooler 18 for cooling hydraulic oil, a radiator 19 for cooling the engine, and a fan 20 for sending cooling air to these are arranged in order of distance from the engine 13, and a gear transmission mechanism 21 is attached to the left output shaft 14. The fan 20 is driven by a fan drive shaft 22 interlockingly connected via the fan.
[0009]
A pulley 23 is attached to the left output shaft 14, and the torque of the output shaft 14 is transmitted to a compressor or an alternator (not shown) for air conditioning via a belt transmission mechanism including the pulley 23.
[0010]
By the way, in the case of a hydraulic excavator used in a place with poor ventilation, such as in a tunnel or a building, or in a place where engine noise is a problem, an electric motor driven by a commercial power supply is used instead of the engine 13 as a drive source. And may be refurbished as a motor driven hydraulic excavator.
[0011]
In this electric motor drive system, a hydraulic pump is connected to one of the left and right output shafts of the electric motor, similarly to the engine drive system.
[0012]
[Problems to be solved by the invention]
In this case, the following problem has occurred due to the drive source being replaced with the electric motor from the engine 13.
[0013]
The engine 13 is usually used at a rotation speed of 2000 rpm or more. However, in the case of a motor, for example, in the case of a 4-pole motor, the output rotation speed is 1500 rpm in a 50 Hz region and 1800 rpm in a 60 Hz region in view of the relationship with the power supply frequency. It is much lower than the number.
[0014]
For this reason, the maximum discharge amount of the hydraulic pump 17 is significantly reduced, so that the original working capacity of the shovel cannot be obtained as it is.
[0015]
Therefore, conventionally, with the conversion to the motor drive system, an inverter system has been adopted in which the speed of the motor is increased to the same level as the engine speed by using an inverter (frequency converter).
[0016]
It is also conceivable to adopt a speed increasing mechanism system in which a speed increasing mechanism (for example, a planetary gear mechanism) is provided between the motor output shaft and the pump input shaft.
[0017]
However, all of these methods increase equipment costs (especially because the inverter itself is expensive in the inverter method, and the control panel for the inverter and noise countermeasures against harmonics are required). In addition to that, the power unit becomes larger by adding an inverter and its control panel or a speed increasing mechanism.
[0018]
For this reason, according to any of the methods, a machine of the same size lacks space particularly in the machine width direction, and it is difficult to fit the machine in the width W in the machine room 12.
[0019]
In this case, a layout change such as placing a part of the power unit (eg, an oil cooler) outside the machine room 12 or modifying the machine room 12 can be dealt with, but the cost is further increased.
[0020]
This problem arises when replacing the engine drive system with an electric motor drive system in a hydraulic work machine such as a dismantling machine or a deep hole excavator, which is constructed by changing the attachment of not only a hydraulic shovel but also a hydraulic shovel as a base. It has arisen in common, and a solution to this point has been desired.
[0021]
Therefore, the present invention provides a hydraulic working machine that can reduce the equipment cost of a power unit and can be easily housed in an existing machine room while reducing the size of the power unit while changing the drive source from an engine to an electric motor. Things.
[0022]
[Means for Solving the Problems]
According to a first aspect of the present invention, an electric motor is installed instead of the engine as a drive source in a machine room in which an engine as a drive source and a hydraulic pump driven by the engine and supplying hydraulic oil to a hydraulic actuator are installed. In addition, a hydraulic pump that satisfies the following conditions is installed instead of the hydraulic pump.
[0023]
Conditions The rated speed of the engine is A1, the maximum discharge capacity of the hydraulic pump using the engine as a drive source is B1, the rated speed of the electric motor is A2, and the maximum discharge capacity of the hydraulic pump using the electric motor as the drive source is B2. As
B1 / B2 ≒ A2 / A1
And
[0024]
As described above, the electric motor is used in place of the engine, and the maximum discharge capacity B2 of the hydraulic pump driven by the electric motor is set to the maximum discharge capacity B1 of the hydraulic pump in the engine drive system.
B2 = B1 · (A1 / A2)
In other words, the pump discharge capacity was increased by the amount corresponding to the decrease in the rated rotation speed of the pump drive source, so that the same pump maximum discharge rate as in the case of the engine drive system was obtained, and the original working capacity of the machine was maintained. Can be secured.
[0025]
Moreover, the increase in size and cost of the pump due to the increase in pump capacity can be significantly smaller than when additional equipment such as an inverter and a speed increasing mechanism is added.
[0026]
Accordingly, it is possible to easily accommodate the existing machine room while suppressing an increase in equipment costs due to the replacement of the power unit with the electric motor drive system and minimizing an increase in occupied space.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
[0028]
In this work machine (explained in the case of a hydraulic shovel), a power unit 32 using a motor 31 as a drive source instead of the engine 13 is installed in the machine room 12 of the shovel shown in FIGS.
[0029]
As shown in FIG. 1, the electric motor 31 is provided in the machine room 12 in a laterally long posture in the machine width direction like the engine 13, and the left output shaft of the output shafts 33 and 34 protruding to the left and right sides thereof. A fan 36 for cooling the oil cooler 35 is attached to 33.
[0030]
Reference numeral 37 denotes a pulley attached to the output shaft 33, and the rotational force of the electric motor 31 is transmitted to a compressor or an alternator (not shown) for air conditioning by a belt transmission mechanism including the pulley 37.
[0031]
In the case of the motor drive system, the output shafts 33 and 34 on both sides are aligned on the center line of the motor, so that the gear transmission mechanism 21 in the engine drive system of FIG. 4 becomes unnecessary. Further, the radiator 19 for cooling the engine becomes unnecessary.
[0032]
An input shaft 39 a of a variable displacement hydraulic pump 39 is connected to the right output shaft 34 via a coupling 38, and the hydraulic pump 39 is driven by the electric motor 31.
[0033]
Here, a hydraulic pump 39 having a larger discharge capacity than the hydraulic pump 17 in the engine drive system shown in FIG. 4 is used, and a decrease in the rated rotation speed of the drive source is compensated for by an increase in the pump discharge capacity. It is configured such that substantially the same pump maximum discharge amount can be obtained.
[0034]
That is, the rated rotation speed of the engine 13 in FIG. 4 is A1, the maximum discharge capacity of the hydraulic pump 17 using the engine 13 as a driving source is B1, the rated rotation speed of the electric motor 31 is A2, and the hydraulic pressure using the electric motor 31 as a driving source is shown in FIG. Assuming that the maximum discharge capacity of the pump 39 is B2,
B1 / B2 ≒ A2 / A1
Is set to
[0035]
Since the rated rotation speed of the electric motor 31 changes according to the power supply frequency (50 Hz, 60 Hz), the maximum inclination of the pump 39 according to the power supply frequency is obtained so that the same pump maximum discharge amount is obtained regardless of the change in the rated rotation speed. The shift position is adjusted.
[0036]
With this configuration, the maximum discharge rates of the two pumps 17 and 39 are substantially equal, and even in this shovel that employs the electric motor drive system, it is possible to secure substantially the same working capacity as the shovel that employs the engine drive system in FIG.
[0037]
Moreover, even if the pump maximum discharge capacity is increased in this way, the size and cost of the pump 39 due to this increase are significantly smaller than when additional equipment such as an inverter and a speed increasing mechanism is added.
[0038]
Therefore, it is possible to suppress an increase in equipment costs accompanying the conversion of the power unit to the electric motor drive system, and to minimize an increase in occupied space.
[0039]
The following table shows comparative examples of the power units 11 and 32 using the engine drive system and the electric motor drive system.
[0040]
[Table 1]

[0041]
As described above, there is no great difference in the total length between the power units 11 and 32, and the total length of the power unit 32 in the electric motor drive system can be suppressed to be equal to or less than the width W of the machine room 12 and easily housed in the machine room 12. Become.
[0042]
In a standard electric motor, a torque of 5 to 6 times the rated torque acts during a stall, so that the diameter of the output shaft is determined so as to withstand such a large torque.
[0043]
On the other hand, as shown in FIG. 2, the motor right output shaft 34 is key-coupled to the coupling 38. In consideration of the fact that a large torque also acts on the key coupling portion 40, this key coupling is standard. In order to increase the length of the portion 40, the output shaft 34 is designed to be longer accordingly.
[0044]
However, in the case of a hydraulic shovel, the torque of the rated torque or more does not actually act on the hydraulic pump 39 due to the action of the relief valve.
[0045]
Therefore, in this excavator, the length L of the output shaft 34 for key connection is set to the minimum size required for connection based on the above-described reality.
[0046]
As a result, the overall length of the power unit 32 can be further reduced, so that the power unit 32 can be more easily accommodated in the machine room 12.
[0047]
By the way, in the above embodiment, the excavator is exemplified as an application object. However, the present invention is applied to a disassembly in which a clamp is mounted instead of the bucket 6 in the attachment 7 in FIG. The present invention can be similarly applied to a deep hole excavator in which a telescopic arm is mounted in place of the drill or the arm 5 and a clamshell bucket is attached to the tip.
[0048]
【The invention's effect】
As described above, according to the present invention, an electric motor is used instead of the engine as a drive source, and the maximum discharge capacity B2 of the hydraulic pump driven by the electric motor is set to the maximum discharge capacity B1 of the hydraulic pump in the engine drive system.
B2 = B1 · (A1 / A2)
A1: Engine rated speed A2: Motor rated speed The relationship is set so that the pump source is switched from the engine to the motor, and the same pump maximum discharge rate as in the case of the engine drive system is obtained. The ability can be secured as it is.
[0049]
In addition, the increase in size and cost of the pump due to the increase in the maximum discharge capacity of the pump is much smaller than when additional equipment such as an inverter and a speed increasing mechanism is added.
[0050]
Accordingly, it is possible to easily accommodate the existing machine room while suppressing an increase in equipment costs due to the conversion of the power unit to the electric motor drive system and minimizing an increase in occupied space.
[Brief description of the drawings]
FIG. 1 is a rear view of a power unit in a hydraulic shovel according to an embodiment of the present invention.
FIG. 2 is a partially enlarged sectional view of FIG.
FIG. 3 is an overall side view of the hydraulic excavator.
FIG. 4 is a rear view of a power unit according to a conventional engine drive system.
[Explanation of symbols]
12 Machine room 32 Power unit 31 Electric motor 39 as drive source Hydraulic pump

Claims (1)

In a machine room where an engine as a drive source and a hydraulic pump driven by the engine to supply hydraulic oil to a hydraulic actuator are installed, an electric motor is installed instead of the engine as a drive source, and the hydraulic pump is Instead, a hydraulic working machine is provided with a hydraulic pump satisfying the following conditions.
Conditions The rated speed of the engine is A1, the maximum discharge capacity of the hydraulic pump using the engine as a drive source is B1, the rated speed of the electric motor is A2, and the maximum discharge capacity of the hydraulic pump using the electric motor as a drive source is B2. As
B1 / B2 ≒ A2 / A1
And

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