FR2483299A1 - HYDRAULIC HAMMER PROVIDED WITH TWO HANDLES CONNECTED TO THE OUTSIDE OF A CYLINDER - Google Patents

Abstract

A hydraulic hammer comprises two handles (50) connected to the outer side of a cylinder (1). When the hammer is in use, this cylinder (1) is continuously passed by a hydraulic liquid. This cylinder (1) is provided with a piston displaced upwards and downwards by means of said hydraulic liquid when the hammer is activated. This hydraulic hammer furthermore comprises a manually operable activating valve (47) located on one of the handles, the inlet (57) of said valve (47) communicating with a space (45) present in the cylinder (1), and the outlet (58) of said valve (47) communicating with the outlet duct (12) of the cylinder. The above space partly defined by a slider (38) communicates with the inlet duct (8) of the cylinder (1) through a throttle opening (59). The slider (38) is shaped so that a liquid force downwardly influencing said slider (38) towards an increasing space size is greater than the oppositely directed force when the connection between the inlet and the outlet of the activating valve is interrupted, and lower when said connection is open. This hammer may be activated without employing mechanical connections, so that a possibility of vibration dampening the handles relative to the cylinder is allowed.

Description

The present invention relates to a hydraulic hammer comprising two handles connected to the outer side of a cylinder continuously traversed by a hydraulic liquid when the hammer is in use, and equipped with a piston which is moved up and down. low using hydraulic fluid when the hammer is actuated, said piston driving, during its up and down movement, a tool such as a chisel projecting from the cylin
dre.

 It is known to actuate a hydraulic hammer by a link acting mechanically between one of the handles of the hammer and a remote-controlled distributor which is placed inside the cylinder. This remote-controlled distributor interrupts the direct flow of hydraulic fluid between the cylinder inlet pipe and its outlet pipe so that the hydraulic fluid drives the piston.

Attempts to dampen the vibrations of the handles relative to the cylinder are made difficult by the presence of said mechanical actuation link between the handle and the remote-controlled dispenser and for this reason, these attempts have not been successful in the past. with regard to hydraulic hammers.

The object of the invention is therefore to provide a hammer which can be actuated without using mechanical connections so that it is possible to dampen the vibrations of the handles relative to the cylinder.
The hydraulic hammer according to the inventson is characterized in that it comprises a manually operable actuation valve placed on one of the handles, the inlet of the valve communicating with a space existing in the cylinder and defined in part by a- movable drawer and partly by portions of the cylinder, the outlet of said valve communicating with the liquid outlet conduit in the cylinder, in that the space partially defined by the drawer communicates with the liquid inlet conduit in the cylinder via a throttle orifice, in that the drawer is shaped so that the force exerted downwards by the liquid on this drawer by pushing it towards a part of increased dimension of said space is greater than the force directed in the opposite direction when the connection between the inlet and the outlet of the actuating valve is interrupted, and is weaker than said force when said connection is open, and in that the drawer, when ledi t space is maximum, is arranged to cut the direct communication between the inlet pipe and the liquid outlet pipe. In this way, we obtain a hammer which allows, in a simple way, a hydraulic actuation only by opening of the actuation valve, so that the liquid in said space can flow through the actuation valve and return to the hammer to then reach the outlet conduit. As a result, the pressure in said space decreases and becomes much lower than the pressure existing in the liquid inside said space, that is to say in the liquid entering the cylinder. This difference in pressure and the dimensioning of the different surfaces of the drawer imply that the pressure prevailing in the liquid penetrating into the cylinder pushes the drawer in the direction of a space of reduced size and consequently opens the direct connection between the inlet duct and the outlet duct of liquid, so that the movement of the piston is stopped. By closing the actuation valve, the liquid entering the cylinder now passes through the throttle opening in the drawer and enters said space, where it is prevented to flow further, and for this reason the pressure prevailing in said space is increased. Consequently, and as a result of the aforementioned dimensions, the drawer is moved by the liquid so that the dimension of said space is increased and the direct connection between the inlet pipe and the outlet pipe is finally interrupted so that the liquid acts on the piston. To actuate the hammer, the user only has to act on the actuating valve so that the connection between its inlet and its outlet is interrupted.

According to the present invention, it is preferred, fable that the drawer is constituted by a cylindrical body
sleeve-shaped, arranged coaxially to the
cylinder and arranged to be moved in the direction
axial of the cylinder, and that the throttle orifice is
formed in the cylindrical wall of the drawer.

Furthermore, in accordance with the present invention,
said space may extend around the outside of the
drawer and this may have a flange making
projecting radially outward and cooperating with the
cylinder wall on one side of an outlet, for
through which said space communicates with the entrance
of the actuation valve, while a first end
usually upper, from drawer, cooperates with
axially extending surface of a protrusion forming
inward projection of the cylinder above the orifice
outlet in said space, and a second end
opposite is arranged to come into sliding contact with
an axially extending surface of a protuberance
protruding towards the inside of the cylinder when the
size of said space is greater than a predefined value
finished, so that the direct flow of liquid to
the outlet duct is interrupted. It follows that
obtains a particularly simple embodiment of the
drawer, which reacts particularly quickly to
closing of the actuation valve by the user.

This is due to the fact that some of the surfaces
cooperants of the drawer which is moved towards a
smaller space can be found on the drawer bezel.

When the opposite end of the drawer approaches the
protrusion of the cylinder which is directed inward
and which cooperates with said drawer, these surfaces are prevented
to be stressed by the relatively high pressure of the
incoming liquid.

Furthermore, in accordance with the present invention, the
drawer can be formed by a solid body in the form of
buffer and the throttle orifice can be formed in the wall of the cylinder, which corresponds to a second advantageous embodiment of the invention.

 This tampon-shaped body can, in accordance with the present invention, be arranged to close an orifice when said space has reached its maximum size, said orifice establishing a direct connection between the inlet conduit and the fluid outlet conduit in the cylinder.

As a result, a particularly simple hammer is obtained.

 Furthermore, in accordance with the present invention, the connection between the actuating valve and the cylinder can be established by means of elastic conduits, so that the hammer is particularly suitable for being equipped with handles with damping.

 In accordance with a particularly advantageous embodiment of the present invention, the actuating valve can comprise a sliding bar acting as a valve body and mounted so as to move in the chamber of the valve, one end of the sliding bar leaving this chamber and abutting against a ratchet which can be manually pushed down and by means of which the sliding bar can interrupt the connection between the inlet and the outlet of the valve when it is desired to actuate the hammer.

 Furthermore, in accordance with the present invention, the inlet port of the actuating valve can open into the valve chamber at a location directly occupied by the sliding bar when it is desired to actuate the hammer, while its outlet port is always placed below the action area of the slide bar. In this way, the actuation valve is automatically opened when the user stops actuating the slide bar. This is due to the fact that the end of the slide bar is always subjected to a certain pressure of liquid.

 According to the present invention, it is particularly advantageous that the handles carrying the actuation valve are fixed on a cylindrical casing mounted with the possibility of displacement around the upper end of the hammer cylinder and that one or more damping springs are placed between the cylindrical housing and the upper end of the hammer cylinder. As a result, a relatively slender hammer is obtained, equipped with handles and having an aesthetic appearance.

 Finally, in accordance with the present invention, the cylindrical casing can surround a damping spring placed essentially coaxially with respect to the cylinder and arranged so as to surround an accumulator connected to said cylinder.

Other advantages and characteristics of the invention will be highlighted in the following description, given by way of nonlimiting example, with reference to the appended drawings in which
FIG. 1 is a sectional view of the upper part of a hammer according to the present invention,
FIG. 2 is a schematic sectional view of the upper part of the cylinder of a hammer according to the invention, as well as a sectional view of the hammer actuation valve,
FIG. 3 is a schematic sectional view of the upper end of the cylinder and of the actuation valve in a second embodiment of the invention, and
- Figure 4 is a sectional view, perpendicular to that of Figure 1, of a part of a hammer according to the invention.

 The part of the hammer of FIG. 1 comprises a double-acting cylinder which is provided with a wall 2. The cylindrical wall 2 surrounds a chamber 3 in which is housed a piston 4 comprising a rod 5. In the position of use of the hammer, this piston rod 5 is directed downwards and leaves the bottom wall (not shown) of the cylinder. The lower outer end of the piston rod is provided, in the embodiment shown, with a hammer head and, in a known manner but not shown, it is arranged to drive a chisel or other suitable tool for the up and down movement of the piston when the hammer is actuated.

The lower end of the piston rod, the piston head and the upper end of the chisel can be surrounded by a tubular part which is arranged at its lower end to receive the upper end of the chisel so that it can be moved forward and backward without falling during hammer operation.

 The cylindrical chamber 3 comprises a lower chamber 6 placed below the piston 4 and an upper chamber 7 placed above the piston 4. The upper chamber 7 communicates, by means of an inlet conduit 8 formed in the part upper part of the cylinder wall, with an inlet orifice 9 formed by a pipe 10 fixed to the cylinder wall so as to be connected to a hose for supplying pressurized hydraulic fluid. The lower part of the cylinder wall is provided with two outlet ducts connected to each other, namely a longitudinal outlet duct 11 and a transverse outlet duct 12.The transverse outlet duct communicates with an orifice outlet 13 formed by a tube 14 fixed on the cylinder wall so as to be connected to a hose discharging the hydraulic fluid to a reservoir or a receiving tank. The longitudinal outlet duct 11 communicates with the transverse duct inside the cylinder wall 2. At the bottom, the lower cylinder chamber 6 comprises an orifice 15 through which it permanently communicates with a longitudinal connecting duct 16.

The upper end of this connecting duct 16 is provided with a control device 17, which will be described in more detail below and which is connected alternately to the upper cylinder chamber for the supply of hydraulic liquid to the lower cylinder chamber and to the longitudinal outlet duct 11 for the evacuation of the hydraulic fluid from the lower cylinder chamber.

The control device 17 comprises a distribution bar 18 which is arranged coaxially with the piston rod. This distribution bar 18 is mounted so as to be able to move in a distribution drawer 19 in the form of a sleeve and in a circumferential projection 20 directed radially inwards on the internal wall of the cylinder. The distribution bar, which is formed or fixed on the piston 4, comprises a first internal conduit 21 establishing a connection between an opening 22 formed at the end of the bar and one or more orifices 23 formed on the side of said bar. In addition, the distribution bar comprises a second conduit 24 establishing a connection between an upper series, indicated by dashed lines, and a lower series of orifices 25 and 26 formed in the side of the bar. 'orifices are mutually spaced in an axial direction on the distribution bar 18 respectively from the first conduit 21 and the piston 4. Their precise locations will be defined in the following description.

The sleeve-shaped distribution drawer 19 includes an upper collar and a lower collar 27, 28 projecting radially outward. The upper collar is arranged to cooperate with a circumferential protuberance 29 of the cylinder wall which projects radially inwards relative to the drawer so that the latter comes into sealed contact with said protuberance when it is in its position. low while away from said protuberance when
is placed in its high position. The lower collar 28 of the dispensing drawer 19 is arranged to abut against the upper side of the lower protrusion 20 projecting inward when it is in its low position and to abut against an intermediate circumferential protrusion 30 of the cylinder wall projecting inwardly when the dispenser drawer
bution is in its upper position. Protuberance
intermediate 30 of the inner cylinder wall and the
protrusion 29 placed completely above the
drawer 19 define a circumferential recess 31. At the
base of this recess 31, an opening 32 is provided by
which said recess 31 communicates with the end
top of the longitudinal connecting duct 16 establishing
communication with the lower cylinder chamber 6.

Between the intermediate protuberance 30 and the protuberance
lower 20, there is provided another recess 33 located immediately below the intermediate protuberance.

At the base of this recess 33, there is an opening 34 through which the recess 33 communicates with the longitudinal outlet duct 11. The axial dimension of the recess 33 and of the lower collar 28 of the dispensing drawer is such that the lower collar 28 of the drawer completely covers the recess 33 when the drawer is in its high position, in which it abuts against the intermediate protuberance 30 while, when the distribution drawer 19 is in its low position, the lower collar 28 is completely out of the recess 33. The intermediate protuberance 30 also has a radial dimension which is such that liquid can flow freely between the slide and this protuberance from the recess 31 provided with the opening opening in the vertical connecting duct 16 and from the recess 33 provided with the opening opening into the longitudinal outlet duct 11 when the distribution slide 19 is in the s its low position. Consequently, in the low position of the distribution slide, a connection is established between the vertical duct 16 and the longitudinal duct 11 and therefore between the lower chamber 6 of the cylinder and the outlet orifice 13. Thus hydraulic fluid can s '' flow from the lower cylinder chamber 6 when the piston 4 is moved down and when the dispensing slide 19 is held in its low position.

 When the distribution slide is in its high position, its lower flange 28 abuts against the intermediate protuberance 30 so that the connection between the vertical duct 16 and the outlet duct 11 is interrupted. However, in this position, the upper collar 27 of the distribution slide 19 eliminates the tight connection with the upper projection 29 of the cylinder wall so that the part of the cylinder chamber which is placed above the slide 19 and the distribution bar 18 is connected to the longitudinal connection duct 16. As a result, hydraulic fluid can flow from the upper chamber to the lower chamber of the cylinder.

 The drawer 19 further comprises a circumferential internal recess 35 at its end closest to the piston 4, as indicated by the dashed lines.

The radial dimension of this recess 35 as well as the axial dimension of the first conduit 21 and the second conduit 24 of the distribution bar 18 are such that the orifices 23 of the first conduit 21 in the side of the distribution bar open into the recess inside 35 of the distribution slide 19 when the piston and the distribution bar connected to the latter are in their low position. When the piston 4 and the distribution bar are adjacent to their high position, the upper series of orifices 25 of the second conduit 24 opens into the recess 35 of the distribution slide 19 at the same time as the lower series of orifices 26 of the second duct opens below the lower protrusion 20 of the cylinder wall. Consequently, when the piston 4 is in its high position, the upper side of the piston 4 and the opposite lower side of the protrusion 20 projecting towards the interior are spaced a predetermined distance, the lower series of orifices 26 of the second conduit 24 of the distribution bar opening into the space between said opposite sides. Via an opening 36 formed in the cylinder wall, this space communicates permanently with the transverse outlet duct 12 formed in the cylinder wall.

A remote-controlled distributor 37 is placed at the upper end of the upper cylinder chamber above the orifice of the inlet duct 8. This remote-controlled distributor comprises a drawer 38 having the shape of a cylindrical body mounted in a manner to be able to move inside the cylinder. This body comprises a collar 39 projecting radially outward so as to enter a circumferential recess 40 formed in the interior wall of the cylinder. This collar 39 is arranged to slide in leaktight fashion along the axial lower surface of the abovementioned inner wall of the cylinder inside said circumferential recess. At the upper end and at the lower end of the circumferential recess 40, an upper groove 41 and a lower groove 42 are provided respectively.

 As indicated in the drawings, the first upper end 43 of the cylindrical slide 38 is arranged to cooperate with the cylinder wall 2 so as to come into sealed contact with said wall during its sliding movement. The second lower end of the drawer 38 is arranged to cooperate with the cylinder wall below the lower groove 42. The drawer 38 and this cooperating part of the cylinder wall are dimensioned so that the second lower end 44 of the drawer slides in tight contact with the cylinder wall in the lower portion of its path. This path is delimited downwards by the coming into contact of the collar 39 with the cylinder wall at the lower end of the groove 42.

Consequently, a circumferential space 45 is defined between the slide and the cylinder wall above the collar 39 projecting radially outwards. The size of this space 45 varies during the movement of the drawer so that it reaches a maximum when the collar 39 abuts against the cylinder wall in the low position of the drawer. As indicated by dashed lines, there is an outlet duct 46 which starts from the lower groove 42. This outlet duct 46 communicates in a suitable manner with the longitudinal outlet duct 11 formed in the wall of cylinder 2 Furthermore, as indicated by dashed lines, the upper groove 41 and the lower groove 42 communicate with an actuating valve 47 by means of respective conduits 48, 49. These conduits 48, 49 pass through suitably the cylinder wall 2. The actuating valve 47 is fixed to one of the handles 50 of the hammer, for example by bolts 51, only one of which is highlighted in the drawing.

In the embodiment shown, the actuating valve comprises a chamber 52 in which a sliding bar 53 can move. This sliding bar 53 extends upwards through an opening 54 formed in the handle 50 and it abuts against an actuating pawl 55 which can be manually pushed down. With the aid of this actuating pawl 55, the sliding bar is moved downwards to a lower position when the user pushes the pawl downwards in the direction of the handle. In FIG. 1, the sliding bar has been shown in its high position, the conduit 48, communicating with the upper groove 41 of the remote-controlled dispenser 37, opens below the lower end of the sliding bar in the chamber 56 where is mounted said sliding bar 53. The opening of the conduit 48, which will be called hereinafter the inlet port 57 of the actuating valve, is positioned so that the sliding bar closes said inlet port when it is pushed down by the pawl to its lower position. In addition, as shown in the drawing, the connection between the valve chamber 56 and the conduit 49 connected to the lower groove 42 of the remote control valve 37, is placed at the lower end of the valve chamber below the orifice d 'inlet 57. The opening corresponding to this connection, which will be called hereinafter the outlet opening 58 of the actuating valve, is placed below the lower end of the sliding bar in any position of the latter.

 In addition, a throttle orifice 59 is provided between the interior side of the sleeve-shaped drawer 38 and the side directed towards the space 45, as shown in FIGS. 1 and 2.

To ensure correct operation of the remote-controlled dispenser, the drawer is profiled and dimensioned so that the force urging the drawer in order to push it down towards an enlarged part of the space 45 is greater than the force directed in the opposite direction. when the connection between the inlet orifice 57 and the outlet orifice 58 of the actuating valve is interrupted, but lower when said connection is open.

Figure 2 shows more schematically the aforementioned drawer and the actuation valve for the sake of clarity. When the actuation valve is open, that is to say when a hydraulic connection is established between the inlet port 57 and the outlet port 58 of the valve, liquid may flow from the space. 45 through the actuating valve to return to the lower groove 42 and also reach, via the outlet duct 46, in the outlet duct 12.

When the hydraulic fluid under a predetermined pressure enters the upper cylinder chamber 7 via the inlet duct 8, and when the drawer is in the position indicated in FIG. 1, the fluid passes through the orifice d constriction 59. Under the effect of the constriction and the connection established between the conduits 48 and 49 via the actuating valve, the pressure prevailing in said space 45 is much lower than the pressure prevailing in the cylinder upper chamber.Moreover, since the extent of the surface 60 directed downwards at the lower end of the drawer is slightly greater than the extent of the surface 61 facing upwards at the upper end of the drawer , the force urging the drawer in a downward direction is less than the force urging the drawer up, the force mentioned first and giggling
u downwards due to the fact that the relatively high liquid pressure manifests inside the cylinder chamber and acts on the surface 61, the relatively low liquid pressure acts on the surface 62 and acts in a direction opposite to the surface 61 on the drawer neck inside the cylinder chamber. The other force biases the drawer upwards due to the pressure acting on the surface 60 by means of inclined transition surfaces 63, possibly provided. It follows that the slide moves upwards, considering FIG. 1, and establishes a direct connection between the upper cylinder chamber 7 and the lower groove 42 and consequently the outlet duct 12. Consequently, the movement of the hammer is interrupted when the drawer is in this position, said position almost corresponding to the position shown in Figure 2.

When the hammer is actuated by manual pushing of the pawl 55 towards the handle 50, the sliding bar 53 interrupts the connection between the inlet port 57 and the outlet port 58 of the actuating valve. As a result, the liquid passing through the throttle orifice 59 causes the pressure to increase in the space 45 and in the conduit 48. The pressure prevailing in the space 45 gradually increases and takes a value sufficiently high to make the force produced by the pressure exerted on the upper surface 62 of the collar and the upper surface 61 of the end of the drawer sufficiently large to overcome the force directed upwards and resulting from the pressure acting on the surface 60 directed towards the bottom and the inclined surfaces 63, possibly provided, as well as the side 64 of the collar which is directed downwards.

Since the surface 64 of the collar 39 directed downwards is placed immediately next to the outlet duct 46, this surface 63 is subjected to a pressure slightly lower than the pressure prevailing in the upper chamber 7 of the cylinder. As a result, when the downward force increased to a value greater than the upward force, the drawer is moved down toward its lower position. When the lower end approaches the cylinder wall, that is to say when the surface 60 is level with the lower end of the recess 40 into which the collar 39 of the drawer penetrates, the pressure urging the lower surface 64 of the collar gradually decreases. Consequently, the speed of the drawer increases gradually during its downward movement.

When the lower end of the drawer 38 comes into contact with the cylinder wall, the direct connection between the cylinder chamber 7 and the outlet duct 12 is interrupted by the drawer and for this reason, the hydraulic fluid under pressure is then available to ensure the drive of the hammer piston, as will be described below.

 FIG. 3 represents a second embodiment of a remote-controlled dispenser 65. This remote-controlled dispenser 65 comprises a massive drawer. buffer 66 which is provided at its upper end with a collar 67 projecting radially outwards. The drawer 66 is mounted so that it can slide in a cylindrical chamber 68, from which the main part 69 of the drawer protrudes through an opening 70. The main part 69 of the drawer 66 is profiled so that the lower end can pass tightly through an opening 71 establishing a connection between the upper cylinder chamber 7 of the hammer and a conduit ab, leaving the outlet conduit 12 when the drawer 66 is in its low position inside the separate chamber 68. A space 72 is delimited by the upper end of the drawer 66 and by the surrounding cylinder wall, said space communicating with the inlet duct 8 of the hammer via a throttle orifice 73 formed in the hammer cylinder paror. In addition, the space 72 is connected to the inlet port 56 of an actuating valve via the conduit 48, said actuating valve corresponding to the valve described above and the orifice outlet 58 of this actuating valve being connected to the outlet pipe 52 of the hammer via the pipe 49.

The buffer-shaped drawer 66 is dimensioned, as shown in the figures. 1 and 2, so that the force urging this drawer down towards a space of increasing volume is greater than the force directed in the opposite direction when the connection between the inlet 56 and the outlet 58 of the actuation valve is interrupted, but is lower when said link is open. When the connection between the inlet port 56 and the outlet port 58 of said actuation valve is open, hydraulic fluid flows through the throttle port 73 into the space 72 then, via the actuating valve, to the outlet pipe 21 of the hammer. The pressure prevailing in the space 72 is lower, owing to the throttling effect, than the pressure prevailing in the pipe inlet 8 and the cylinder chamber 7 and for this reason the slide moves upward under the action of high pressure stressing its lower end. When the buffer-shaped drawer reaches its high position, a direct connection is established between the upper cylinder chamber 7 and the outlet duct 12 and for this reason the hammer is not actuated
in this position. When the actuation valve is stressed and when the connection between its inlet port 57 and its outlet port 58 is interrupted, there is established in space 72 a pressure which is finally sufficiently large to overcome the pressure directed in opposite. The drawer is then moved downwards so as to close the passage comprising the orifice 71. When this orifice 71 is closed, the liquid pressure prevailing in the cylinder chamber 7 is available to drive the piston 4 of the hammer , as described above.

The outlet port 58 of the actuating valve 47 is placed, as mentioned above, so that it is always located below the lower end of the slide bar 53, the low position of which is indicated by a line in broken lines between the inlet orifice 57 and the outlet orifice 58 in FIGS. 2 and 3.

Consequently, the lower end of the sliding bar is always subjected to the pressure prevailing in the duct 49, that is to say the pressure existing in the outlet duct of the hammer and for this reason, the sliding bar 53 is automatically moved up to the open position when the user stops pushing down on the pawl, i.e. a force directed towards the handle. Consequently, the drawer 66 also automatically moves back to its high position where the direct connection between the upper cylinder chamber 7 and the outlet duct 12 is established, the hammer being thus automatically stopped when the user no longer pushes the pawl 65 down.

 Of them. accumulators are attached to the outside of the cylinder wall. The first accumulator 74 communicates with the upper cylinder chamber 7 via a conduit 75 while the second accumulator (not shown to clarify the drawing) communicates with the hammer outlet conduits. These accumulators can be of any desired type. The function of the accumulators is to retain the hydraulic fluid during the drive of the hammer piston.

The hammer works as follows
When it is not actuated, the remote-controlled distributor 37 is in its high position, where the opening of the longitudinal duct 11 of the hammer communicates with the upper cylinder chamber 7. When the intake port 9 and the orifice outlet 14 of the hammer are connected to the supply hose and the discharge hose and when hydraulic fluid is supplied under pressure to the hammer, liquid flows continuously into the intake duct 8 to enter the upper chamber cylinder 7.

The liquid leaving this chamber 7 flows directly upwards below the drawer 38 and it leaves the hammer, after having passed through the conduit 46 and the conduit 12, via the return hose channeling the liquid up to to a receiving tank or tank. In this position, the accumulators are almost in a discharged state.

 When the hammer is actuated by the operator who manually exerts a downward thrust on the pawl 55, the sliding bar 53 of the actuating valve 47 is pushed axially downward from the top of the valve so that the connection between the inlet orifice 57 of this valve and the remote-controlled distributor 37 is interrupted. As a result, the drawer is pushed down to its lower position so that the connection between the upper cylinder chamber 7, the duct 46 and the outlet duct 12 is interrupted.

Initially the pressure prevailing in the upper cylinder chamber 7 is increased at the same time as the accumulator 74 is charged. The increase in pressure in the upper cylinder chamber 7 implies that the piston 4 is immediately pushed down since the upper end of the distribution bar 18 is stressed by the pressure prevailing in the upper chamber 7, said upper end acting the role of the upper surface of the piston. During this movement, the distribution slide 19 is placed in its lower position, as shown in FIG. 1. In this position, a connection is established between the lower cylinder chamber 6 and the longitudinal outlet duct 11 so that the liquid hydraulic located in the lower cylinder chamber 6 is forced out of the hammer during the downward movement of the piston. Since the space 76 existing between the protuberance
o lower rance 20 of the inner wall of the cylinder and the upper side of the piston 4 during the liquid discharge movement is increased, the outlet conduits are subjected to a suction effect. This suction effect would produce strong pulsations inside the discharge hose if the accumulator (not shown) did not exist. However, these pulsations are avoided since the accumulator supplies the outlet conduit with hydraulic liquid.

The supply of hydraulic fluid to the hammer is obviously maintained for any position of the remote-controlled distributor and, for this reason, the upper cylinder chamber is continuously supplied with hydraulic fluid. Immediately after charging the accumulator 74, it also supplies hydraulic fluid, during the downward movement of the piston. When the piston 4 reaches the predetermined low position, the orifice 23 of the first conduit 21 of the distribution bar 18 reaches the area adjacent to the inner circumferential recess 35 of the dispensing drawer 19 so that the liquid flows downwards to enter the space defined by the recess 35, the dispensing bar 18 and the inner protrusion 20 of the cylinder wall. As a result, the distribution slide 19 begins to slide upwards, thus allowing a flow of the hydraulic fluid between the lower side of the lower collar 28 of the distribution slide 19 and the upper side of the lower projection 20 of the cylinder which makes protruding inward, which produces a faster upward movement of the drawer.

 When the piston reaches its low position, the hammer head strikes the chisel, not shown, and transmits its energy to it. Consequently, the downward movement of the piston is stopped. At this time the accumulator (not shown) has supplied all the liquid it contains and is now completely discharged while the accumulator 74 is in a condition between the fully discharged state and the fully charged state.

Since the liquid is supplied under pressure to the lower side of the dispensing drawer 19 via
from the first conduit 21, the distribution slide 19 comes
strike against the intermediate protuberance 30 of the
inner wall of the cylinder which projects inward
laughing and then stopped in its up position. As
previously mentioned, the connection between the lower chamber
re cylinder 6 C the outlet duct 11 through
of drawer 19 is interrupted in this high position of
drawer. On the contrary, the connection between the lower chamber
of cylinder 6 and the upper chamber of cylinder 7 is
open so that hydraulic fluid flows under
downward pressure of upper cylinder chamber 7
towards the lower cylinder chamber 6.
causes a displacement of the piston 4, and consequently of
distribution bar 18, upwards towards the top
cylinder. The individual parts are sized
so that the connection between the upper chamber and the
cylinder lower chamber be established almost at
same time the piston reaches a spaced low position
a predetermined distance from the bottom of the cylinder. Of this
way, the hydraulic fluid being below the
piston can dampen the movement of this piston if the hammer,
for some reason, was not equipped with a chisel.

Hydraulic fluid obviously flows
in the upper cylinder chamber 7 from
the power source and through the supply hose
The accumulator (not shown) is, in this condition,
still discharged while the accumulator 74 communicating with the upper cylinder chamber is being charged.

In a location between the low position and the
high position of the piston and during its return strokes,
the connection between the upper cylinder chamber 7 and the
bottom side of the dispenser drawer 19 is interrupted
so that hydraulic fluid is trapped in
the space defined by the distribution drawer 19, the bar
distribution 18 and the inner wall of the cylinder between
the lower collar 28 of the drawer 19 and the protuberance
lower 20 of the cylinder wall. As a result, the drawer is still held in its upper position so that hydraulic fluid can flow continuously from the upper cylinder chamber 7 down into the lower cylinder chamber 6. During the return strokes of the piston 4, liquid is also forced out of the space 76 between the upper side of the piston 4 and the lower protrusion 20 delta inside wall of the cylinder. In this way liquid is partially discharged via the return hose and it is partially pushed into the accumulator (not shown). The accumulator 74 is also charged with the liquid supplied.

 The distribution slide 19 is held in its high position until the piston 4, and consequently the distribution bar 18, arrive in the vicinity of their upper positions. The second conduit 24 of the distribution bar 18 then ensures a connection with the volume of liquid maintained below the drawer 19 so that the liquid can flow in the space 76 existing between the upper side of the piston 4 and the side lower protrusion 20 of the inner wall of the cylinder, to exit therefore through the transverse conduit 12. This implies that the distribution slide 19 is no longer blocked in its upper position by the trapped liquid and begins to descend under the influence of the pressure existing in the upper cylinder chamber 7, thereby forcing the trapped liquid through the second conduit 24 of the distribution bar 18.

 As soon as the slide 19 reaches its low position, the connection between the upper cylinder chamber 7 and the lower cylinder chamber 6 is interrupted and for this reason the upward movement of the piston 4 is stopped in a condition corresponding essentially to the situation put highlighted in Figure 1. The two batteries are now charged and ready to go into operation. As long as the remote-controlled dispenser 37 is kept in its low position, this operating cycle is repeated continuously. The desired movements of the mobile parts are ensured by an appropriate dimensioning of the surfaces, stressed by the hydraulic liquid, of said mobile parts, such as the distribution bar 18, the piston 4 and the drawer 19.

When the user wishes to interrupt the movement of raising and lowering the hammer, he releases the pawl 55 so that the pressure prevailing in the internal cylinder chamber 7 automatically pushes the drawer 38 of the remote-controlled distributor 37 upwards as a result of the pressure difference being established between the upper cylinder chamber 7 and the space 45 delimited by the drawer 38. In this way, the direct connection between the upper cylinder chamber 7 and the external duct 46 is established and the movements of the hammer are arrested
The handle of the hammer is fixed on a cylindrical casing 77, visible in FIG. 1. This casing coaxially surrounds the upper end of the cylinder and it is mounted so as to be able to move around the upper end of the cylinder. A suitable spring 78 is disposed between the upper end of the cylinder and the upper inner end of the cylindrical casing 77, said spring also extending coaxially with the cylinder and surrounding the accumulator 74 placed at the upper end of the cylinder. The cylinder block77 is arranged, as shown in Figure 4, so as to move in an axial direction relative to the cylinder within a predetermined range which is defined by suitable control and stop means. In the embodiment shown, these control and stop means consist of a bar 79 fixed to the cylindrical casing and extending parallel to the axis of said casing. This bar 79 is also engaged, with the possibility of displacement. , in a projection 81 of the cylinder wall which is provided with a suitable opening.

The lower end of the bar 79 is provided, as indicated, with a thread 82 receiving a nut 83 with the aid of which the range of displacement of the cylindrical casing 77 can be adjusted. If necessary, the hammer can be provided with several such control and stopping means. Due to the possibility of adjusting said control and stopping means, the user can create an appropriate prestress in the spring 78 disposed between the upper end of the cylinder 1 and the cylindrical casing 77.

During the use of the hammer, the spring ensures an adequate damping of the vibrations of the handles relative to the cylinder so that the use of the hammer is much less tiring than when the handles are directly fixed on the cylinder of the hammer. With regard to vibration damping handles, the connections between the inlet port 57 and the outlet port 58 of the actuating valve on the one hand and the cylinder on the other hand are suitably established using elastic hoses forming the aforementioned conduits 48 and 49.

 Of course, the invention is not limited to the embodiments described above and shown, from which other modes and other embodiments can be provided, without thereby departing from the scope of the invention. Many other known types of actuating valves can for example be used and it is also possible to use several springs in place of the single spring shown.

Claims (10)

 1. Hydraulic hammer comprising two handles (50) connected to the outside of a cylinder (l) through which hydraulic fluid continuously flows when the hammer is in use and which is provided with a piston (4) moved upwards and downwards by said liquid when the hammer is actuated, said piston ensuring, during its up and down movement, the driving of a tool such as a chisel projecting from the cylinder (1), characterized in that that it comprises an actuating valve (47) which can be operated manually and placed on one of the handles (50), the inlet (57) of the valve communicating with a space (45,72) existing in the cylinder (1) and partly defined by a movable drawer (38,66) and partly by portions of the cylinder (1), the outlet (58) of said valve communicating with the outlet conduit (12) of the liquid in the cylinder (1), in that the space (45,72) partially defined by the slide (38,66) communicates with the liquid inlet conduit (8) in the cylinder (1) via a throttle orifice (59,73), in that the drawer (38,66) is shaped so that the force exerted downwards by the liquid on this drawer by pushing towards an enlarged part of said space (45,72) is greater than the force directed in the opposite direction when the connection between the inlet (57) and the outlet (58) of the actuating valve is interrupted, and is weaker than this force when said connection is open, and in that the drawer (38,66), when said space (45,72) is maximum, is arranged to cut the direct communication between the inlet duct (8) and the liquid outlet conduit (12).  2. Hydraulic hammer according to claim 1, characterized in that the drawer is a cylindrical body (38) in the form of a sleeve which is arranged coaxially with respect to the cylinder (1) and which is arranged to move in the axial direction of this last and in that the throttle orifice (59) is formed in the cylindrical wall of the drawer (38). 3. Hydraulic hammer according to claim 2, characterized in that said space (45) extends around the outside of said drawer (38) and in that the drawer (38) comprises a collar (39) projecting radially towards the exterior and cooperating with the cylinder wall (2) on one side of an outlet orifice, through which said space communicates with the inlet (57) of the actuating valve, while a first usually upper end (43) of the drawer (38) cooperates with an axially extending surface of an inwardly projecting portion of the cylinder (1) above the outlet of the space (45), and in that a second opposite end (44) is arranged to come into sliding contact with a surface, extending axially, of a projection oriented towards the inside of the cylinder (1) when the quantity of space (45) is greater than a predetermined value, so that the direct flow of liquid to the outlet conduit (12) is interrupted.  4. Hydraulic hammer according to claim 1, characterized in that the drawer is a solid body (66) in the form of a buffer and in that the throttle orifice (73) is formed in the cylinder wall (2).  5. Hydraulic hammer according to claim 4, characterized in that the body (66) in the form of a buffer is arranged to close an orifice (71) when the space (72) has reached its maximum size, said orifice establishing a direct connection between the inlet pipe (8) and the outlet pipe (12) of the liquid in the cylinder.  6. Hydraulic hammer according to any one of claims 1 to 4, characterized in that the connection between the actuating valve (47) and the cylinder (1) is established using elastic conduits (48,49) .  7. Hydraulic hammer according to any one of claims 1 to 5, characterized in that the actuating valve (47) comprises a sliding bar (53) acting as a valve body and mounted so as to be able to be move in the valve chamber, one end of said sliding bar projecting from the chamber (52) of the actuating valve (47) and abutting against a pawl (55), which can be manually pushed down and by the through which the sliding bar (53) interrupts the connection between the inlet (57) and the outlet (58) of the valve when it is desired that the hammer be actuated.  8. Hydraulic hammer according to claim 6, characterized in that the inlet orifice (57) of the actuating valve (47) opens into the valve chamber at a place directly filled by the sliding bar (53) when it is desired that the hammer be actuated while its outlet orifice (58) is always located below the action zone of the sliding bar (53).  9. Hammer according to any one of claims 5 to 7, characterized in that the handles (so) and the actuation valve (47) are fixed to a cylindrical casing (77) mounted with the possibility of displacement around the upper end of the hammer cylinder (1) and in that one or more damping springs (78) are provided between the cylindrical casing (77) and the upper end of the hammer cylinder.  10. Hydraulic hammer according to claim 8, characterized in that the cylindrical casing (77) surrounds a damping spring arranged essentially coaxially with respect to the cylinder (1) and arranged to surround an accumulator (74) connected to said cylinder.