Mechanical hydraulic excavator with ground compaction function

Abstract

To provide a mechanical type hydraulic pressure shovel capable of avoiding delay at the instance when movements between lowering of a leveling device and lift of a boom are reversed.SOLUTION: A mechanical type hydraulic pressure shovel includes a jack V1, a pump 31, a hydraulic pressure device 3, a control mechanism 4, a control unit 6, a graph 61 (pressure and temperature) of a vapor pressure of a working liquid, a comparator 62, and a control mechanism 5. The control unit 6 controls the operation of a shovel in a normal operation mode of adjusting flow rates Q of a valve and the pump 31 according to a signal (SC) of the control mechanism 4 and a leveling mode required by the control mechanism 4 so that an arm part freely descends due to an action of its weight, the valve fully opens an outlet C1 of the jack V1 toward a storage part 33, and the pump 31 supplies a fuel to an inlet C2 of the jack V1, and keeps the pressure to be higher than a vapor pressure of the working liquid and lower than an atmospheric pressure at a temperature of the working liquid in the jack V1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] In addition to normal use as an excavator, the present invention aims at a mechanical hydraulic excavator capable of performing a ground consolidation operation using excavator tools.

[0002] Background Art It is known to use a mechanical shovel for soil consolidation, and such is known, for example, from U.S. Patent No. 2011 / 0013982. This known shovel uses a ground consolidation tool installed at the tip of the arm in addition to or instead of the bucket. By the movement of the boom with the arm and the tip tool, the ground in front of the mechanical shovel can be consolidated.

[0003] However, this operating mode of the mechanical hydraulic excavator has several drawbacks. Since the weight of the tool is used to lower the boom with the ground consolidation tool, this operation causes decompression due to the action of cavitation in the jack that operates the boom. Furthermore, the reverse movement between lowering the tool by gravity with the boom, arm, and bucket or ground consolidation tool and then raising the tool in the reverse movement is delayed due to the wasted time at the moment of exactly reversing.

[0004] Object of the Invention An object of the present invention is to develop a mechanical hydraulic excavator that performs not only the normal functions of an excavator but also a ground consolidation function and avoids the delay at the moment of reversing the movement between lowering the ground consolidation tool and raising the boom towards a new stage of ground consolidation.

[0005] Disclosure and Advantages of the Invention Therefore, the present invention is a mechanical hydraulic excavator, - a vehicle body having a revolving body provided with an arm (boom, arm) with a tool such as a bucket having a ground consolidation surface at the tip, - a jack connected to the arm and supported by the revolving body, - A hydraulic device having a pump capable of adjusting the flow rate for supplying fuel to the jack via a spool valve, and a storage section for the working fluid, - A control mechanism operated by an operator to generate a control signal, and a control unit connected to a pressure and temperature sensor for the working fluid in the jack that generates a signal S(P-T), - A graph (pressure and temperature) of the vapor pressure of the working fluid available in the control unit, - A comparator that receives the signal from the sensor, compares the signal with the vapor pressure curve, and generates a control signal for the pump, - A control mechanism that the operator operates to supply a control signal for the operation mode to the control unit, - The control unit, - A normal operation mode in which the flow rates of the valve and the pump are adjusted according to the signal from the control mechanism, - A ground consolidation mode required by the control mechanism so that the arm freely descends under the action of its weight, controls the operation of the excavator, - The valve fully opens the outlet of the jack toward the storage section, - The pump supplies fuel to the inlet of the jack and maintains the pressure higher than the vapor pressure of the working fluid but lower than the atmospheric pressure at the temperature of the working fluid in the jack, aims at a mechanical hydraulic excavator.

[0006] The mechanical hydraulic excavator according to the present invention has the advantage of operating extremely efficiently in the ground consolidation mode. The hydraulic circuit avoids the development of cavitation action when the arm and the ground consolidation tool rapidly descend under the action of their weights.

[0007] Thereby, the excavator retains its efficiency for both normal operation and ground consolidation at the same time. Without cavitation, the working fluid is sent to the jack during descent, shortening the time between the end of this descending movement and the start of the arm rising, so that it can effectively return to the high position after descent.

[0008] This operation does not limit the amplitude of the movement of the arm in any case. Depending on the work to be performed, the arm can be lifted to any position within the range of movement that the jack can achieve, while maintaining the efficiency of counteracting the cavitation effect.

[0009] According to an advantageous feature, the electronic control unit is a computer that uses a program to manage the operation in the normal mode and the ground consolidation mode.

[0010] This electronic control unit may be a unit that manages the overall operation of the hydraulic excavator, and in this unit, the normal operation mode and the ground consolidation mode are program modules.

[0011] According to another advantageous feature, the hydraulic excavator is provided with a manual control device connected to the control unit so that the control unit can switch to the first operation mode or the second operation mode and operate the lowering and raising movements of the arm using the first control device. The second control device is a switch or a push button.

[0012] The hydraulic excavator according to the present invention advantageously uses a bucket such as a ground consolidation tool, but this does not exclude installing a specific ground consolidation tool instead of the bucket and replacing it with the bucket.

[0013] However, for this replacement, it is necessary to remove the bucket and install the tool, and during this intervention, it will stop the operation of the excavator. It is not possible to use the hydraulic excavator with a bucket as an excavation tool alternately, and in parallel with it, or while it is stopped, as a ground consolidation tool.

Brief Description of the Drawings

[0014] The present invention will be described below using the embodiments shown in the accompanying drawings.

Figure 1

Figure 2A

Figure 2B

[0015] Description of Embodiments of the Invention FIG. 1 schematically shows a mechanical hydraulic excavator 100, which has a movable body 110 with crawlers, for example, and a revolving body 120 including a driver's cab and a motor 1, an arm 2 including a working tool, and a hydraulic device 3. The arm 2 is formed of a boom 21 connected to the revolving body 120 via a connecting portion A1 and a jack V1 that controls the rotation around the connecting portion A1. The boom 21 is followed by an arm 22 connected to the boom 21 via a connecting portion A2 and a jack V2 that controls the rotation of the arm 22 around the connecting portion A2.

[0016] The end of the arm 22 is connected to a working tool 23 such as a bucket and a jack V3 via a connecting portion A3. The bucket 23 can be tilted so that its outer surface 231 is used as a surface for compacting the ground or a tool for compacting the ground.

[0017] The jack V3 controls the movement of the bucket 23, the jack V2 controls the movement of the arm 22 and its bucket 23, and the jack V1 controls the movement of the boom 21 and the components (22, 23) held by the boom, that is, the entire movement of the arm 2.

[0018] The jacks V1, V2, and V3 are supplied with hydraulic fluid in a controlled manner by a hydraulic device 3 equipped with valves such as a pump 31 and a spool valve 32 according to the movement to be executed. Each group of jacks V1 to V3 or jacks is controlled by a corresponding lever not described in detail, which forms part of a hydraulic control block, for example, and the hydraulic control block is connected to a spool valve such as a valve 32 that controls the hydraulic fluid supplied to the jacks and, in some cases, other accessories of the mechanical excavator 100.

[0019] According to the present invention, the hydraulic excavator 100 can not only perform a normal excavation function (mf1) using the bucket 23, but also perform a ground consolidation function mf2 using the bucket 23. This ground consolidation function mf2 uses a rigid arm 2 formed by the boom 21, the arm 22, and the bucket 23. This arm 2 is controlled by the jack V1 to rotate around the connecting portion A1, moves downward using gravity, and moves to raise the bucket 23 by supplying fuel to the jack V1.

[0020] Regarding the description of the hydraulic device 3, it is limited to the means necessary for this operation mode mf2 using the jack V1.

[0021] The jack V1 is divided by a piston P in the bottom chamber C1 and the rod side chamber C2 of the jack T. Generally speaking, the hydraulic fluid in the chamber C1 pushes out the rod T, and in the chamber C2, it pulls back the rod T.

[0022] Each of the chambers C1 and C2 is connected to the spool valve 32 via respective pipelines CC1 and CC2 through which the hydraulic fluid flows back and forth simultaneously. The spool valve itself is connected to the pipeline CP coming from the pump 31 and the pipeline CR returning to the tank 33, and fuel is supplied to the pump 31 at this tank.

[0023] To make the explanation easy and simple, since the roles of the chambers C1 and C2 are reversed in the raising and lowering of the arm 2 (or the boom 21), the connection between the chambers C1 and C2 and the respective pipelines CC1 and CC2 is required according to the direction in which the hydraulic fluid effectively flows as follows: In the case of raising, - The inlet EC1 of the chamber C1 - The outlet SC2 of the chamber C2 In the case of lowering, - The outlet SC1 of the chamber C1 - The inlet EC2 of the chamber C2 In other words, - In raising, the pump 31 supplies fuel to the jack via the chamber C1 (inlet EC1), - During lowering, the pump 31 supplies fuel to the jack V1 via the chamber C2 (inlet EC2).

[0024] The hydraulic device 3 is managed by a control unit 6 that is connected to a first control mechanism 4 in the form of a lever and a second control mechanism 5 for switching between functions mf1 and mf2. This control mechanism 5 is in the form of a lever or a push button. The switching can also be performed based on an operating motion that repeats according to a specific pattern of the control mechanism 4, and this pattern is interpreted as a switching signal between the two functions mf1 and mf2 by the control unit 6.

[0025] The first control mechanism 4 manages the operating mode mf1 or mf2 of the jack V1 among the two operating modes selected by the second control mechanism 5: Normal operation mf1 Ground consolidation mf2 Among them, it manages the operating mode mf1 or mf2 of the jack V1.

[0026] Ground consolidation mf2 is the operating mode that is particularly the subject of the present invention.

[0027] Ground consolidation consists of pressing and compacting the ground using the bucket 23 and the arm 22 that rotate around the connecting part A3 so that the outer surface 231 of the bucket 23 becomes the compacting surface. The repetitive movement of raising and lowering the arm 2 is controlled by the operator using the lever 4. This movement needs to be repeated as quickly as possible to enable the operation of the hydraulic circuit 3 and the movement of the arm 2.

[0028] According to the present invention, the valve 32 has three switching regions Po, P1, P2 on the spool 321 in order to block the two pipelines CC1, CC2 of the jack V1 or to connect these two pipelines to two pipelines CP, CR corresponding to the inlet from the pump 31 and the return port to the tank 33 respectively.

[0029] The region Po of the valve closes the two pipelines CC1, CC2, thereby stopping the jack V1 in its position, that is, stopping the piston P of the jack V1 at the position where it is located inside at that time.

[0030] In this region Po, the pipelines CP and CR are closed, or in a modified example, the fluid is also returned from pipeline CP to pipelines CR and tank 33. This enables the pump 31 to continue functioning even when the jack V1 is disconnected from the circuit.

[0031] Region P1 connects chamber C1 to pump 31 and chamber C2 to tank 33.

[0032] Region P2 connects chamber C2 to pump 31 and chamber P1 to tank 33.

[0033] Regions P1 and P2 reverse the operation of the jack V1, and between these two regions, region Po stops the operation of the jack V1.

[0034] Put simply, this region P1 corresponds to the active fuel supply from pump 31 to jack V1, while region P2 corresponds to the passive operation of jack V1. In the latter case, chamber C1 is emptied by the piston P being pushed by the weight of the arm 2.

[0035] Unit 6 moves spool 321 by two actuators AC1 and AC2 at both ends of the spool 321, and controls valve 32 by the actuators pushing and pulling the spool to a selected position relative to pipelines C1, C2 or CP, CR. In the mf2 mode, regions P1 and P2 are not proportional. Both regions fully open or close the passage of the working fluid, and the switching between regions P1 and P2 passes through region Po regardless of the switching direction.

[0036] The control unit 6 manages the operation of pump 31 (pump flow rate Q) based on the instructions of lever 4 and information provided by sensors (not shown) and monitors the operation of the hydraulic device 3.

[0037] The control unit 6 is connected to a pressure sensor 34 that detects the pressure in the chamber C2 of the jack V1. This pressure sensor is connected to the pipeline CC2 connected to the chamber C2 or the pipeline CP leading out from the pump 31. The sensor 34 or another connected sensor measures the temperature of the hydraulic fluid in the chamber C2 of the jack or at the inlet of this chamber. The sensor provides a pressure signal SP and a temperature signal ST to the control unit 6.

[0038] This signal is also represented in the form S(P - T) which combines the pressure signal and the temperature signal, and this is provided either by the signal itself or by two sensors.

[0039] The control unit 6 stores the vapor pressure curve of the hydraulic fluid 61 and has a comparator 62 that compares the pressure signal S(P - T) provided by the sensor 34 with the vapor pressure curve of the hydraulic fluid, and controls the operation of the pump 31.

[0040] The graph of the vapor pressure of the hydraulic fluid is a known curve in the coordinates (T, P) where the liquid state and the gas state are separated, which is not shown in the figure. Cavitation generally occurs when the pressure of the liquid falls below the pressure curve at a constant temperature, and when the curve changes to a constant pressure and rising temperature, the liquid will boil.

[0041] The operation in the first mode mf1 consists of controlling the rotation of raising and lowering the arm 2 or the boom 21 by supplying fuel to the chamber C1 or the chamber C2.

[0042] The operation in the second mode mf2 is different in that it uses the weight of the arm 2 (boom, arm, and bucket) to lower the arm 2 and pound the surface of the ground S for ground consolidation under the bucket 23.

[0043] The operation of the lever 4 is performed by transmitting control signals SC1, SC2 for controlling the raising or lowering of the arm 2 to the unit 6.

[0044] Initially, the arm 2 is lowered and is, for example, supported on the ground, or at some position among the raised positions (depending on the maximum stroke of the jack V1), or at an intermediate position due to a stop after the operation has ended. The spool 321 is, theoretically, in the neutral position Po that stops the jack V1.

[0045] The operation to be performed is the compaction operation (in the operating mode mf2).

[0046] The unit 6 detects the start of the movement of the lever 4 and interprets this movement as a request to supply fuel to the jack V1 in the direction of raising the arm 2. The unit 6 pushes the spool 321 to the region P1, supplies fuel to the chamber C1 (active fuel supply), and at the same time connects the chamber C2 to the return path CR to the reservoir 33.

[0047] The operator operates the lever 4 to the intermediate position or to the end of the stroke.

[0048] The operation continues for the same length of time as the time the lever is actuated and for the same length of time as the jack V1 can operate in that direction, that is, until the chamber C1 is completely full. A stroke sensor or a pressure sensor corresponding to the chamber C1 stops the pump 31 or switches the spool 321 to shift to the region Po.

[0049] When this operation ends, the movement of the arm 2 stops, and if the lever 4 does not reach the rest position, the lever should return to its original position. The lever may be released by the operator and automatically return to that position.

[0050] The operation that must follow after raising the arm 2 is detected by the control unit 6, and the control unit controls the spool 321 to bring the region P2 to the operating position, connect the pipeline CR to the pipeline CC1, and connect the pipeline CP to the pipeline CC2.

[0051] The communication via the spool 321 is fully open for the two pipelines CC1, CC2, that is, the flow rate returning from the chamber C1 to the liquid storage section 33 (also referred to as the tank) is not restricted, and the flow rate Q from the pump 31 to the chamber C2 is also not restricted.

[0052] The pump 31 feeds liquid under the control of the unit 6, supplies fuel to the chamber C2, and keeps the pressure slightly higher than the vapor pressure of the working fluid and lower than the atmospheric pressure at that temperature, so as to avoid cavitation or the start of cavitation, not allowing excessive inflow into the chamber C2, and ensuring that the operation following the raising of the arm does not lag.

[0053] To control the pump 31 and the flow rate / pressure Q of the pump, the control unit 6 compares the pressure of the working fluid in the chamber C2 supplied with fuel by the pump 31 with the vapor pressure at the temperature of the working fluid in the chamber C2 to control the flow rate Q of the pump 31, so that when the movement of the bucket 23 stops and the bucket is not necessarily at the final position of the stroke of the piston P in the cylinder, it can immediately start moving in the reverse direction.

[0054] This state is detected by detecting a change in the pressure gradient in the chamber C2 of the boom jack V1, and this change is caused by the impact on the ground. This becomes the pressure peak. Normally, the operator impulsively reverses the control 4 at the moment of hearing the sound caused by the bucket colliding with the ground. Therefore, the spool 321 automatically positions to the position Po to stop the arm 2 and prevents any movement before the arm 2 is controlled to rise as desired by the operator.

[0055] When automatically stopping like this at the end of the descending stroke under the action of the weight, the lever 4 may still be at the final position of the descending stage of the arm 2.

[0056] For the next stage of raising the wrist 2, the lever 4 needs to pass through the rest position again. Next, when the lever 4 is actuated, the control unit 6 detects the start of control, positions the spool 321 of the valve at position P1 to supply fuel to chamber C1, and raises the wrist 2 to the end of the stroke of the jack V1 or to the height position selected by the operator according to the work to be performed. Then, the compaction cycle starts again.

[0057] The lever 4 controls the pump 31 as depicted by the curves in FIGS. 2A and 2B.

[0058] FIG. 2A shows a graph of the operation of the lever 4 with time T on the horizontal axis and the stroke of the lever 4 on the vertical axis.

[0059] The stroke is represented on a scale of 0% to 100% of the full stroke.

[0060] The movement of the lever 4 starting from the origin O(0%, to) is, for example, linear. The stroke may stop at any level, for example, at the level of X% of the full stroke. When the operator reaches this point (instant t1) selected, the operator holds the lever 4 until instant t2 and then raises, lowers, or releases the lever. At that time, the lever automatically returns to the position of 0% on the horizontal axis in a relatively short return time.

[0061] FIG. 2B shows the control function applied to the pump 31 by the control unit 6 to control the flow rate Q. This function is assumed to be linear and is represented in correspondence with the time of the curve in FIG. 2A. In this case, the vertical axis represents the flow rate Q as a percentage of the maximum flow rate (100%) of the pump 31. The degree of actuation (X%) of the lever 4 corresponds to the flow rate Q(X%).

[0062] The image of the operation of the pump 31 is that the requirement represented by the signal of the lever 4 is approximately the same as the known operating capacity of the jack V1, and as long as that capacity is applied by the control unit 6, the lever 4 is actuated.

[0063] According to the present invention, the flow rate Q of the pump 31 that supplies fuel to the chamber C2 is such that the pressure in the chamber C2 does not fall below the vapor pressure of the working fluid when the bucket 3 descends due to gravity, or the pressure of the working fluid does not generate a pushing force on the piston and increase the pressure of the weight applied by the arm 2. It is adjusted to avoid the formation of cavitation in the jack, or to prevent the time taken to reverse the movement of the boom and then raise it from becoming too long.

[0064] The delay in raising the arm 2 after lowering it occurs because it first fills the space in the chamber C2 when stopping or changing direction, and it takes time for the working fluid to reach the chamber C1 due to the time required to discharge the working fluid with the pressure in the chamber C2.

[0065] The repetition of the ground consolidation work cycle for each cycle - The stage of raising the arm 2 to the required height corresponding to the end or intermediate position of the stroke of the jack V1 - The lowering stage of releasing the arm 2 and applying a load to the arm by the action of the weight until the bucket 23 (or the ground consolidation tool) hits the ground S is included.

[0066] The control unit 6 is preferably a computer applied to a program that manages the operation of the mechanical excavator 100 and compliance with safety conditions in the normal mode (mf1) and the ground consolidation mode (mf2).

Explanation of Signs

[0067] 100 Mechanical hydraulic excavator 110 Body 120 Swing body 1 Motor 2 Arm 21 Boom 22 Arm 23 Tool / Bucket 231 Ground consolidation surface 3 Hydraulic device 31 Adjustable pump 32 Spool valve 321 Spool 33 Storage part of the working fluid, tank 34 Pressure / temperature sensor 4 Lever 5 Another control mechanism 6 Control unit UC 61 Graph of the working fluid (P-T) 62 Comparator Al, A2, A3 Connection part V1, V2, V3 Jack P Piston of jack V1 T Rod of jack V1 C1, C2 Chambers of jack V1 CC1, CC2 Pipelines connecting to the chambers of the jack CP Pipeline coming out of the pump CR Pipeline returning to the tank S Ground SC Signal of control mechanism 4 S(P-T) Pressure signal - temperature signal of the working fluid in jack V1 SP Control signal of pump 31 SCmf Control signal for switching between operating modes mf1 Normal mode mf2 Ground consolidation mode

Claims

1. A mechanical hydraulic excavator (100), A vehicle body (110) having a revolving body (120) provided with an arm portion (2) (boom (21), arm (22)) with a tool (23) such as a bucket (23) having a ground compacting surface (231) at its tip, A jack (V1) connected to the arm portion (2) and supported by the revolving body (120), A hydraulic device (3) having a pump (31) capable of adjusting the flow rate for supplying hydraulic fluid to the jack (V1) via a spool valve (32), and a storage portion (33) for the hydraulic fluid, A control unit (6) connected to a control mechanism (4) operated by an operator to generate a control signal (SC), and a sensor (34) for the pressure and temperature of the hydraulic fluid in the jack (V1) that generates a signal S(P - T), A graph (61) (pressure and temperature) of the vapor pressure of the hydraulic fluid usable within the control unit (6), A comparator (62) that receives the signal S(P - T) from the sensor (34), compares the signal with a vapor pressure curve (P - T), and generates a control signal (SP) for the pump (31), A control mechanism (5) operated by the operator to supply a control signal (SCmf) for an operation mode (mf1, mf2) to the control unit (6), Comprising, The control unit (6) A normal operation mode (mf1) in which the flow rate (Q) of the spool valve (32) and the pump (31) is adjusted according to the signal (SC) of the control mechanism (4), A ground compacting mode (mf2) required by the control mechanism (4) so that the arm portion (2) freely descends under the action of its weight, Controls the operation of the mechanical hydraulic excavator (100), The spool valve (32) fully opens the outlet (C1) of the jack (V1) toward the storage portion (33), The pump (31) supplies fuel to the inlet (C2) of the jack (V1) and maintains the pressure higher than the vapor pressure of the hydraulic fluid but lower than the atmospheric pressure at the temperature of the hydraulic fluid in the jack (V1), Mechanical hydraulic excavator (100).

2. The mechanical hydraulic excavator according to claim 1, characterized in that the control unit (6) is a computer using a program for managing operations in the normal operation mode (mf1) and the ground compacting mode (mf2).

3. The mechanical hydraulic excavator is provided with a manual second control device (5) connected to the control unit (6) so as to switch the control unit (6) to the normal operation mode (mf1) or the ground consolidation mode (mf2) and operate the lowering and raising movements of the arm part (2) using the manual first control device (4), and the second control device (5) is a switch or a push button. The mechanical hydraulic excavator according to claim 2.

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