JP2008019680A - Mechanism for assisting operation of boom for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for preventing a useless energy loss to further improve fuel productivity. <P>SOLUTION: One end of an elastic body 3 is directly or indirectly fixed to a vehicle body 2, and the other end is directly or indirectly fixed to a boom 1 so that the reaction of the boom in rising operation can be utilized as energizing force. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mechanism for assisting the vertical movement of a boom of a work machine.

  The operation of a work machine such as a hydraulic excavator is a combined operation of a vertical operation of a front work device (for example, a boom, an arm, etc.) and a swing operation of an upper swing body. For example, excavation and sediment loading work of a hydraulic excavator includes the steps of (1) excavation and filling of buckets of earth and sand, (2) the step of moving the earth and sand filled in the buckets to a position where it is loaded onto a truck, and (3) sediment of the buckets It consists of four steps: a process of dropping onto a truck (hereinafter referred to as a soil removal process) and (4) a process of returning the bucket from the truck to the excavation position (hereinafter referred to as a return process). In (1), the boom, arm and bucket Up and down movement, (2) boom raising and turning actions, (3) arm and bucket up and down movements, and (4) boom lowering and turning actions.

By the way, when lowering the boom once lifted during these operations, the return pressure oil on the boom cylinder head side is throttled by the control valve in order to avoid a sudden lowering operation.
JP 2006-9888 (0002 stages)

  From the viewpoint of energy transfer, the potential energy at the height of the front work device was converted to heat energy in the oil passage of the throttle spool of the control valve and lost. In other words, there is an inherent problem that energy is wasted when the front work apparatus is lowered.

  In addition, there is a problem that the load factor of the engine cannot be made uniform and the fuel productivity is deteriorated because the load of the work machine process is too large. For example, in the work of the hydraulic excavator, a high load (engine load factor) is applied to each operating part during the operations of (1) and (2). In the return process of (), only the operation of lowering the empty bucket and turning makes the load low. The engine of the work machine is designed so that the fuel efficiency (the ratio of the work rate to the unit fuel) is maximized at the maximum load (maximum horsepower), so the fuel efficiency is good at the high load of (1) and (2). On the other hand, when the load is extremely low as in the return process (4), the fuel efficiency is also extremely lowered. The operation in which the low load is maintained deteriorates the fuel productivity.

  The present invention was devised in view of the above-described problems of the prior art, and seeks to provide a technique capable of preventing wasteful energy loss and further improving fuel productivity.

  For this reason, the operation assisting mechanism for a boom for a work machine according to the present invention has one end of the elastic body directly on the vehicle body and the other end directly on the boom so that the reaction force can be used as a biasing force when the boom is raised. Or it is characterized by being indirectly fixed.

  Here, indirect fixing means fixing via another member. As shown in an exemplary embodiment to be described later, an existing member (for example, a boom cylinder) may be interposed, or a new member (for example, a link member that performs a movable operation) may be disposed and the member may be interposed.

  In the present invention, the boom raising operation is urged using the reaction force of the elastic body. The elastic body is arranged so as to generate a reaction force in the boom raising operation direction. In other words, this means that the elastic body is deflected during the boom lowering operation. The energy that causes deflection during the boom lowering operation is at least the potential energy due to the boom's own weight (strictly speaking, the amount of displacement between the potential energy of the boom that was generated at a certain height and the potential energy of the lowered position) This is preserved as the deflection of the elastic body. That is, in the present invention, the potential energy of the boom is used as a source of reaction force. As described above, this potential energy is conventionally lost as thermal energy due to the restriction of the hydraulic circuit. As described above, the present invention is a mechanism that effectively utilizes energy that has conventionally been wasted.

  Also, during boom lowering operation, the rod side pressure of the boom cylinder increases by the amount of deflection of the elastic body, so that the load required for lowering the boom increases compared to the conventional case, and compared with other work that becomes high load. Load bias is corrected. As a result, the uneven load factor of the engine is corrected and fuel productivity is improved.

  As described above, in the mechanism according to the present invention, the reaction force of the elastic body is used as an assist for the raising operation during the boom raising operation, but further assistance may be added to this configuration. Conventionally, a so-called regeneration circuit that returns pressure oil from the head side of the boom cylinder to the rod side has been used to improve the actuator speed and reduce the pump flow rate when the boom is lowered (see, for example, Patent Document 1). . In this regeneration circuit, when the cylinder contraction direction is operated, the hydraulic oil is regenerated from the cylinder head side to the rod side. However, in the same circuit, when the cylinder is extended, the hydraulic oil flows from the cylinder rod side to the head side. If it does, it will become the assistance at the time of the raising operation of the pressure oil and boom. Therefore, such a configuration is defined as the invention of claim 2. That is, according to the invention of claim 2, in addition to the above configuration, an oil passage directly connecting the rod side port and the head side port of the boom cylinder is formed, and pressure oil flows from the rod side port to the head side port during the boom raising operation. It is characterized by being controlled as follows.

  As described above, according to the present invention, the potential energy that has been lost when the boom is lowered can be used when the boom is raised, and wasteful energy loss can be prevented to effectively reduce fuel consumption.

  Further, since the load at the time of lowering the boom is increased as compared with the conventional case, the load unevenness with respect to other work is corrected, thereby correcting the uneven load of the engine load factor and improving the fuel productivity of the work machine.

  An example of a specific form according to the present invention will be described with reference to the drawings. The following examples are all examples applied to the boom of a hydraulic excavator, but it is of course possible to apply this to other work machines.

  FIG. 1 shows a first embodiment. This embodiment is an example in which a compression spring 3 is used as an elastic body, and its upper end is fixed directly to the bottom of the boom 1 and its lower end is directly fixed to the body 2 below the boom 1 (note that 4 is an arm, and the arm A bucket is connected to the tip of 4 (not shown).

  In this embodiment, the extension force of the compression spring 3 is used as the urging force during the boom 1 raising operation. Since the extension force acts as a reaction force of the spring 3, selection of the spring force of the spring to be used is important.

  This spring force selection will be described with reference to FIG. FIG. 2 shows the operating range of the boom 1, where (a) is the highest boom position, (b) is the horizontal position, and (c) is the lowest position (excavation start position). When the spring constant of the spring (elastic body) is k and the amount of deflection is X, the potential energy U of the boom 1 when the boom is at the weight M and the height h is expressed by the following equation.

  In order for this potential energy to be preserved and for the extension force of the spring to act when the boom 1 is raised, the extension force, which is the reaction force of the spring, is at least a position where the boom 1 is lower than the horizontal position (A). (U side) needs to be larger. However, since the boom 1 may be raised from the horizontal position (A) to a position higher than that position (A side) during work, the extension force is at the maximum position (A) at the lowest position (C). ) Is more preferably minimized.

  In this embodiment, it is assumed that such a condition is satisfied, and the extension force is minimized when the boom is at the highest position (A) (the optimum is the natural length, but in reality there may be some deflection), and the boom A spring having a spring force that balances with the weight of the boom when the is in a substantially horizontal position (A) is used. The amount of potential energy stored in the spring at each position is as shown in FIG.

  Therefore, in this embodiment, for example, when the boom 1 is lowered from the highest position (a) to the excavation start point (c) in order to perform excavation work, the potential energy corresponding to the height H is contracted to the spring 3 in the boom 1. It is stored as (deflection). For this reason, when the boom 1 is lifted after scooping earth and sand with a bucket (not shown), the potential energy stored as a contraction (deflection) in the spring 3 becomes an extension force as a reaction force, and the lifting operation is applied. It will be. Since the energy for the boom 1 raising operation is not required for this energization, the oil power supplied from the pump to the boom cylinder 5 can be reduced, resulting in a mechanism for improving fuel efficiency.

  In addition, when the operation of lowering the boom 1 with the bucket empty (for example, the return step (4) above), which causes the engine load to be extremely reduced, the spring 3 is caused to contract (deflection), Since the load increases, the load unevenness during other work is corrected, thereby correcting the engine load factor unevenness and improving the fuel productivity of the work machine.

  In the first embodiment, the form in which the reaction force of the elastic body serving as the urging force appears as an extension force is shown. However, since the reaction force only has to be urged to the lifting operation of the boom 1, the extension force is not necessarily limited. It is not necessary to be, but rather various forms are conceivable. For example, in FIG. 3, the spring 30 is fixed to the back side of the boom 1 (the other end is fixed to the airframe bracket 20), and when the boom 1 is raised, the contraction force as a reaction force of the spring 30 is used. ing. In this embodiment, potential energy is stored in the spring 30 as extension (deflection) when the boom 1 is lowered. 4 shows that the inner end of the spiral spring 31 is fixed to the central axis 10 of the boom 1 (the outer end is directly fixed to the fuselage 2), and when the boom 1 is raised, the spiral spring 31 is released as a reaction force. It is a form that uses power. In this embodiment, when the boom 1 is lowered, the potential energy is stored in the spiral spring 31 in the form of compression.

  Further, the elastic body such as a spring may be fixed indirectly through another member. For example, as shown in FIGS. 5 to 10, link members 60 to 69 interlocking with the vertical movement of the boom 1 are arranged, and springs 32 are attached to the link members 60 to 69 (70 and 71 are auxiliary members). One end of -37 may be fixed, and the other end may be fixed to the airframe 2 (of course, the airframe side may also be fixed via another member). The fixing may be fixed to the fixing member with a pin (for example, 32a, 33a, 35a, 37a), or may be fixed to the swinging member and the end thereof may swing.

  Furthermore, you may fix through the member already equipped in the body 2, and the example is a form example shown in FIG. Although this is the second embodiment, in this embodiment, one end is fixed to the boom 1 and the other end is fixed to the barrel end 51 with the spring 38 fitted into the rod 50 of the boom cylinder 5. ing. This embodiment is basically similar to the first embodiment, in which the extension force of the spring 38 is used as a reaction force to bias the operation when the boom 1 is raised. A further feature of this embodiment is that the boom cylinder This is because a return oil passage similar to a so-called regeneration circuit is formed in the five oil passages.

  That is, as shown in FIG. 11, the oil path of the boom cylinder has a head-side port connected to the pump 6 and a rod-side port connected to the tank 7, but the head side port and the rod-side port are directly connected to the circuit. An oil passage is formed, and a regeneration valve 8 and a check valve 9 for returning pressure oil from the rod side to the head side are arranged there. Then, when the cylinder rod 5 is extended, that is, when the boom 1 is raised, a controller (control means) (not shown) controls the pressure oil to flow through the return oil passage, thereby assisting the boom 1 raising operation. By the return oil and the biasing of the reaction force of the spring 38, the amount of oil from the pump 6 required for the boom 1 raising operation can be reduced, and a more significant saving effect can be obtained. This return oil passage may use a conventional regeneration circuit.

  The embodiment described above is a specific example of the invention according to the claims of the present application, and other forms are applied by using an applied work machine, an elastic body / hydraulic circuit to be used, and other configurations. It is natural to go.

  The present invention can be applied to a work machine having a boom.

It is explanatory drawing of the 1st form example. It is a figure explaining the relationship between the height of a boom and potential energy, (a) is a state diagram of a boom, (b) is a graph which showed the amount of potential energy in each state of (a). It is explanatory drawing of the other example of a form. It is explanatory drawing of the other example of a form. It is explanatory drawing of the other example of a form. It is explanatory drawing of the other example of a form. It is explanatory drawing of the other example of a form. It is explanatory drawing of the other example of a form. It is explanatory drawing of the other example of a form. It is explanatory drawing of the other example of a form. It is explanatory drawing of a 2nd form example, and is a hydraulic circuit.

Explanation of symbols

1 Boom
2 Airframe
3,30-38 Elastic body
5 Boom cylinder

Claims (2)

A boom for a working machine characterized in that one end of an elastic body is directly or indirectly fixed to the vehicle body and the other end is directly or indirectly fixed to the boom so that the reaction force can be used as a biasing force when the boom is raised. Motion assist mechanism.   2. An oil passage directly connecting a rod side port and a head side port of the boom cylinder is formed, and control is performed so that pressure oil flows from the rod side port to the head side port during a boom raising operation. Operation assist mechanism for booms for work machines.

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