EP0672506B1 - Hydraulic percussion hammer - Google Patents

Abstract

A hammer housing (20) connected to a pressure conduit (10) and a backflow conduit (12) contains a working cylinder (21) in which a piston (22) is movable and a back space (50) in which the rearward end of the hammer piston moves. A control device (40) introduces pressure fluid into the working cylinder, and the piston alternatively executes forwardly directed work strokes and back strokes. The piston during the work stroke strikes against an anvil surface (23). To the back space a pressure gas accumulator (52) is connected and the back space is connected to a pressure source via a feed conduit (55), contg. a pressure-controlled valve (58). The valve supplies a constant pressure which is lower than that in the pressure conduit (10), and the back space remains closed during the back stroke of the piston.

Description

The invention relates to a hydraulic hammer, especially for advancing objects in the Ground.

From the patent DE 30 23 538 C2 is a hydraulic Percussion hammer with the features of the generic term of Claim 1 known. This hammer is a compressed gas storage at the back of the working cylinder connected, the gas space through a membrane is closed, on the outside of which in the Hydraulic fluid contained in the rear of the working cylinder acts. The back room is through an inflow pipe, which contains a valve controlled by pressure, connected to the inlet pipe. Furthermore, the Rear area via a second line to the control device connected to when the working piston has reached its front end position, the control body to change the control device into that state, in which the control device the return stroke of the Working piston causes. The second line is thus a pure pressure control line through which no transport of pressurized fluid takes place. The pressure-controlled Valve connects the rear space of the working cylinder the supply line when the working piston is its has reached the front end position. During the return stroke the pressure in the working area increases. If this pressure exceeds a certain value, then connects the pressure-controlled valve to the rear area with the return line. In this way the Working piston pumped hydraulic fluid and a certain Exchange of the amount of liquid contained in the rear area causes. The main part of the impact energy is through the Pressure gas accumulator applied. The fact that from the Back space of the working piston pressure fluid is drained when the pressure in this back space is at its maximum has reached, some of the printing energy is lost, which deteriorates the efficiency of the hammer.

The invention has for its object a hydraulic To create a hammer in which the ratio improved from impact energy to power consumption is.

This object is achieved with the invention the features specified in claim 1.

In the impact hammer according to the invention, the back space fully completed when the working piston leaves its front end position until the rear Reversal point is reached, and preferably until the working piston reached its front end position again Has. A particular advantage is that none Print energy is lost. For the return stroke increased pressure force of the working piston will, however, this additional energy will be used recovered on the working stroke when the Pressure gas accumulator relaxed. Then that from the return surface of the working piston in turn displaced the Pressure delivery system fed so that the hammer drill overall no higher consumption of hydraulic Pressure energy has as a hammer drill without compressed gas storage. Still, the impact energy that comes with Support is achieved through the compressed gas storage much larger than in a system without compressed gas storage. The pressure controlled valve ensures that at the beginning of the return stroke in the rear area of the working cylinder there is a defined pressure. During the return stroke of the working piston increases this Pressure steadily because the working piston turns into a complete closed system, from which no hydraulic fluid escapes. Therefore also find no energy losses take place, with the exception of friction losses. It is also achieved that the compressed gas storage a defined braking energy for the return stroke applies, the braking force with the return stroke of the Working piston increases steadily without pressure surges or shock.

The one enclosed in the rear space of the working cylinder Hydraulic fluid heats up during the Field operation. To overheating this Avoiding pressure oil is advisable in the rear area to an inflow line and an outflow line connected to flow through the rear only are open when the working piston is in the Located near its front end position. In this The rear has its largest volume and condition Pressure in the back area takes its minimum value. The Hydraulic oil then flows briefly through the pressure chamber, until the working piston makes its return stroke. The flow path becomes during the return stroke through the inflow line and the outflow line interrupted. The one then trapped in the back room Liquid becomes an ever increasing pressure exposed, the contained in the compressed gas storage Gas is compressed. The flow through the back area serves the partial renewal of the in the back room contained oil for the purpose of heat dissipation and on the other hand to build up a defined pressure in the Back space before the compression phase. Any oil loss past the working piston after each working stroke replaced.

The efficiency is particularly good if the Compressed gas storage in connection with a hammer is used, in which the return displacement constantly the is exposed to high delivery pressure. The hydraulic fluid which displaces from the back area during the working stroke will remain under pressure and will not be in the tank relaxed into it.

The invention is generally for advancing objects, e.g. Spuntbohlen can be used, but is suitable also for rock breakers and drilling devices. The hammer is preferably at the rear end of the item arranged as an external hammer, but it can also be designed as a deep hole hammer.

The following are with reference to the Drawings embodiments of the invention closer explained.

Fig. 1

einen schematischen Längsschnitt durch eine erste Ausführungsform des Schlaghammers,

Fig. 2

einen schematischen Längsschnitt durch eine zweite Ausführungsform des Schlaghammers, und

Fig. 3

eine dritte Ausführungsform.

Show it:

Fig. 1

2 shows a schematic longitudinal section through a first embodiment of the percussion hammer,

Fig. 2

a schematic longitudinal section through a second embodiment of the hammer, and

Fig. 3

a third embodiment.

The hammer drill shown in Fig. 1 has a hammer housing 20 on that to a pressure line 10 and to a unpressurized return line 12 is connected, and in which a working cylinder 21 is included. In the working cylinder 21, the working piston 22 is guided. The front end of the working piston 22 strikes one Anvil surface 23 of an adapter 24 in the hammer housing 20 is guided longitudinally within limits. The adapter 24 is with the object to be driven coupled.

"Front" means the direction in each case which points in the direction of advance and with "behind" the opposite direction.

The working piston 22 has a forward facing annular return stroke surface RF on the annular front cylinder space (return stroke space) 26 limited. This Cylinder chamber 26 is always connected via a line 27 the pressure line 10 connected. The return stroke area RF delimits a thickened section 28 of the working piston. The other limitation of section 28 is of an annular surface 29 is formed, to which a thinner Section 30 joins. Behind the thinner section 30 again follows a thicker section 31, the rear End is formed by a work surface AF. The working area AF limits the rear cylinder space 33 of the working cylinder 21. The working surface AF is greater than by a factor of 2 to 3 the return stroke area RF.

The return stroke surface RF moves along several Control grooves 34a, 34b, 34c in the front cylinder space 26. The annular surface 29 moves along a control groove 35. In the area of the thinner section 30 of the working piston opens out with the return line 12 connected line 36 in the working cylinder 21. Die Control grooves 34a, 34b, 34c are connected to a control line 37 connected. There are two of these connections closed with locking devices 32 while one is open. The control groove 35 is always with the Control line 37 connected. The rear cylinder space 33 of the working cylinder is to an operational management 38 connected.

The control of the working piston 22 is carried out by the Control piston 41, which is movable in the control cylinder 40 is. The control piston 41 is designed as a hollow sleeve. Since the control cylinder 40 with the pressure line 27th is connected, there is inside the control piston 41 always the full hydraulic pressure. The control piston 41 has a first work surface A1 at one end, which is constantly under pressure and radial grooves has, so that the pressure can attack her. At the opposite end of the working piston a second work surface A2 that is smaller than that Work area A1. The control piston is with an annular collar 42 provided at one end by a Control surface A3 and at the opposite end an always unpressurized area A4 is limited, which with the return line 12 is connected. The control surface A3 is exposed to the pressure of the control line 37. The Control piston 41 is also provided with an annular groove 43, which in any position of the working piston with the Return line 12 is connected. The pressure line 27 is a compressed gas storage 44, which acts as a buffer connected to smooth the hydraulic pressure surges is.

The impact device described so far works as follows:

The operational management is in the state shown in FIG. 1 38 about the inside of the control piston 41 connected to the pressure line 27 so that on the work surface AF the full pressure works. Because the work surface AF is larger than the return stroke area RF on which The working piston also guides the full pressure 22 from its forward working stroke the end of which he strikes the anvil surface 23. As soon as the return stroke area RF passes the open control groove 34b has, the control line 37 from the pressure line 27th severed. If the control surface 29, the control groove 35 has passed, the control line 37 is via the groove 35 connected to line 36 and thereby depressurized. Thus acts on the control surface A3 of the control piston 41 no more pressure. The control piston is moved back because the force exerted on the work surface A1 will exceed the force exerted by the same pressure the work surface A2 is exercised. If the control piston has reached its upper end position, the Operating line 38 separated from the delivery pressure and connected to the return line 12 via the annular groove 43. As a result, the return stroke of the working piston 22 causes. As soon as the groove 35 thickened on the return stroke Piston part 28 is shut off and the groove 34 from the return stroke area RF is released, arises in the Control line 37 the full pressure on the control surface A3 acts and the spool in the lower end position drives. The sum of the control areas A2 and A3 is larger than the control area A1.

The rear space 50 of the hammer housing 20, in which the rear approach 51 of the piston extends filled with hydraulic fluid. This back room 50 is closed on all sides and with a compressed gas storage 52 connected. The compressed gas storage 52 contains a gas filling in a gas space 53. The gas space 53 is limited by a flexible membrane 54 which is gas impermeable and which closes the rear space 50.

An inflow line leads laterally into the rear space 50 55 leads in and on the opposite side an outflow line 56 out of the rear space. The Outlet line 56 contains a throttle point 57 and it is connected to the return line 12. The inflow pipe 55 contains a pressure control valve 58, which with the Flow line 10 is connected. The pressure control valve 58 generates a pressure of 20 in the inflow line 55 bar. The working pressure supplied to the feed line 10 is 180 bar.

Located in the front end position of the working piston the end face of the projection 51 in the position 59, which is shown in dashed lines in Fig. 1. In this Position are the mouths of the inflow line 55 and the discharge line 56 released into the rear space 50, so hydraulic fluid through the back room can flow. During the subsequent return stroke of the working piston The approach 51 closes the lines 55 and 56. The pressure in the back space 50 then increases until the forward force of the gas accumulator 52 in Balance to that acting on the return stroke surface RF Strength is. This means that the pressure p in the rear area 50 equal to the working pressure P (in the feed line 10) multiplied by the area ratio RF: SF. When the SF face is four times larger than that Return stroke area RF and the working pressure is 180 bar, the pressure in the rear area 50 increases to 180: 4 = 45 bar. The pressure of the pressure control valve 58 is dimensioned so that an increase in pressure during the return stroke of the working piston to this value (45 bar). This applies to the maximum working stroke, i.e. if the Control grooves 34a and 34b closed and the control groove 34c is open.

The embodiment of FIG. 2 is largely the same 1, so that the following description limited to the differences.

2 is in the inlet line 55, which in the Leads back space 50, contain a check valve 60, that only opens towards the back room 50, blocks in the opposite direction. Line 55 is too here connected to the control valve 58, the pressure in the feed line 10 to a predetermined value (e.g. 20 bar) reduced. The drain line 56a is not connected to the return line, but with the control groove 35 and with the control line 37. If the Working piston 22 reaches its front end position has, the annular surface 29 releases the control groove 35, so that this is now via line 36 with the return line 12 is connected. Therefore, only in the front position of the working piston 22 the outflow line 56a connected to the return line 12. At the following stroke sweeps over the ring edge 29 the control groove 35 so that this from the working piston is closed and the outflow line 56a is blocked.

2 sweeps over the Return stroke area RF not the control groove 35. The reversal at the end of the return stroke, that the pressure in the rear space 50 and in the outflow line 56a, which on the control surface A3 of the control piston 41 acts so large that he the spool 41 in pushes the position shown in Fig. 2, in which the Piston executes its stroke. The tax groove 34 is therefore not required in FIG. 2. The reversal of the control piston 41 takes place with the help of the pressure in Back room 50.

Lead the inflow line 55 and the outflow line 56a into the back room 50 at a point where it not blocked by the approach 51 of the working piston can be.

3 differs of that of Fig. 2 in that the inflow line blocked by the approach 51 of the working piston and is released, as is the case in FIG. 1 is. In contrast, the outflow line 56b in FIG. 3 not controlled by the working piston. It is constant connected to the rear space 50, as shown in FIG. 2 the case is.

In both exemplary embodiments, FIGS. 2 and 3, the control piston 41 is reversed into that Position corresponding to the working stroke of the working piston 22 corresponds to the pressure in the outflow line 56a and 56b. This pressure changes depending on from the return stroke position, that of the working piston 22 each takes and depending on the pressure that generated by the pressure control valve 58 in the rear space 50 has been while the piston is in the extreme feed position was. This pressure the the pressure control valve 58 is generated in the rear space 50, is called a form. By changing the form can the path length of the working piston at Return stroke can be set at which the pressure in the Outflow line 56a (Fig. 2) or 56b (Fig. 3) as large is that it can switch the control piston 41. By Changing the admission pressure from the pressure control valve 58 is generated, the size of the piston stroke of the working piston to be changed. If the form is small, the working piston goes through a long return stroke, until the pressure in the discharge line 56a or 56b so has grown large that the control piston 41 switched becomes. Because of the large stroke length of the working piston there is a lower number of strokes per minute and an increase in the impact energy. Is on the pressure control valve 58 the form in the back 50 on one large value is set, the reversal of the Control piston even with a small stroke length of the Working piston. In this case, the working piston does Blows with high impact frequency and low impact energy.

A change in stroke rate and energy can in the embodiments of FIGS. 2 and 3 also take place in that the delivery pressure, the Pressure line 10 is fed, is varied while the pre-pressure generated by the pressure control valve 58 is kept constant becomes. The control piston 41 forms one Pressure compensator, on the one hand the full high pressure of the Pressure line 10 (on the end faces A1 and A2) exposed and on the other hand the pressure in the discharge line 56a (Fig. 2) or 56b (Fig. 3), which on the Control surface A3 acts. If the delivery pressure is reduced, the stroke frequency of the working piston is increased and the impact energy is reduced. If the delivery pressure is increased, the stroke rate is reduced and the Impact energy increased.

A change in stroke rate can be dependent of how far the object is carried out is already driven into the ground. At the beginning of the Driving an object into the ground is first worked at a high frequency. Is the Soil is already advanced, a higher feed rate will be achieved reached when the stroke rate decreases and the energy of the single blows is increased. The Beat frequency can also be dependent automatically of the feed force acting on the hammer to be changed.

In the embodiment of Fig. 1, the rear space 50 during the return stroke of the working piston locked that the working piston the lines 55 and 56 cordoned off. In the embodiment of 2, the closing of the rear space 50 takes place on the one hand through the check valve 60 and on the other hand in that the one connected to the discharge line 56a Annular groove 35 is closed by the piston part 28, while the control line 37 one to the control cylinder 40 leading dead end forms. In the embodiment 3, the rear space is closed 50 in that the line 55 from the working piston is closed and that with the discharge line 56b connected annular groove 35 closed by the piston part 28 becomes, while the control line 37 a dead end forms.

In all embodiments of the hammer, the Return stroke area RF be larger than in the case that on no gas cushion at the rear end of the working cylinder is available. The larger return stroke area RF is necessary because more force has to be applied to the gas in the Compressed gas storage 52 to compress. The enlarged Return stroke area RF has the consequence that the oil volume in the front cylinder chamber 26 becomes larger. For this Cylinder chamber 26 becomes the oil volume with each working stroke repressed. However, since the return stroke surface RF is constantly Exposed to high pressure, it remains under pressure standing oil volume, which displaces from the cylinder chamber 26 was received under pressure. This volume of oil need not be supplemented by the external hydraulic pressure source become.

Claims (12)

1. A hydraulic impact hammer, comprising:

   a hammer housing (20) connected to a pressure line (10) and a return line (12) and including a working cylinder (21) for movement of a working piston (22) therein, and a rear chamber (50) for movement of the rearward end of the hammer piston therein,

   a control means (40,41) for introducing pressure fluid into the working cylinder (21) in such a manner that the working piston (22) alternately performs forwardly directed working strokes and return strokes,

   the working piston (22) striking against an anvil surface (23) in the working stroke,

   and the rear chamber (50) having a pressure gas reservoir (52) connected thereto and the rear chamber (50) being connected to a pressure source via an inflow line (55) including a pressure-controlled valve (58),

   characterized in
   that the pressure-controlled valve (58) supplies a constant pressure lower than the pressure in the pressure line (10), and that the lines connected to the rear chamber (50) are controlled to keep the rear chamber (50) closed after the beginning of the return stroke of the working piston (22).
2. The impact hammer according to claim 1, characterized in that the rear chamber is connected to an outflow line (56;56a,56b) which, when the working piston (22) is near its forward end position, is connected to the return line (12) to cause a flow through the rear chamber (50).
3. The impact hammer according to claim 2, characterized in that the inflow line (55) and the outflow line (56a,56b) are opened only when the working piston (22) is near its forward end position.
4. The impact hammer according to any one of claims 1 to 3, characterized in that the inflow line (55) and/or the outflow line (56) open into that region of the rear chamber (50) which is traveled through by the rearward end of the working piston so that the inflow line (55) and/or the outflow line (56) are adapted to be closed by the working piston.
5. The impact hammer according to any one of claims 2 to 4, characterized in that the outflow line (56) includes a throttle site (57) or a valve,
6. The impact hammer according to any one of claims 2 to 5, characterized in that the outflow line (56a,56b) is connected to a control line (37) which is pressureless in the forward end position of the working piston (22) and which in the return stoke is separated from the return line (12) by the working piston.
7. The impact hammer according to claim 6, characterized in that the control line (37) controls the control means (40,41).
8. The impact hammer according to any one of claims 1 to 7, characterized in that the working piston (22) comprises a return stroke surface (RF) constantly subjected to the high pressure.
9. The impact hammer according to any one of claims 1 to 8, characterized in that the inflow line (55) includes a one-way valve (60) arranged to open towards the rear chamber (50).
10. The impact hammer according to any one of claims 1 to 9, characterized in that the reversal of the control means (40,41) is effected when, at the end of the return stroke, a balance of forces between the pressure acting upon the return stroke surface (RF) and the pressure acting upon the front surface (SF) has been obtained at the working piston (22).
11. The impact hammer according to any one of claims 1 to 10, characterized in that the pressure of the pressure-controlled valve (58) is adjustable to change the length of the return stroke of the working piston (22).
12. The impact hammer according to any one of claims 1 to 11, characterized in that the amount of the supply pressure supplied to the pressure line (10) is adjustable to change the length of the return stroke of the working piston (22).

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