Abstract
A hand-guided ground compacting machine, such as, in particular, a vibration tamper, a vibratory roller or a vibratory plate, comprising a driving engine mounted on a machine frame, a ground compaction device driven by the driving engine, and a guide bar. Features of the present invention reside in that the driving engine is a liquid gas powered driving engine and that the ground compacting machine comprises at least one storage container for liquid gas which is replaceably disposed in a storage container holding means on the hand-guided ground compacting machine.
Claims
1. A hand-guided ground compacting machine, comprising: a driving engine which is mounted on a machine frame; a ground compaction device driven by the driving engine; and a guide bar, wherein the driving engine is a gas powered driving engine, that the hand-guided ground compacting machine comprises at least two storage containers for liquified petroleum gas (LPG) connected to the driving engine via a piping system, and that a storage container holder is provided for accommodating and storing the at least two storage containers on the hand-guided ground compacting machine with the piping system comprising an attachment device configured for parallel connection of the at least two storage containers to the piping system, with a protective cover comprising a hood being located above the at least two storage containers, the protective cover having a pair of protective tubes disposed on an interior surface of the protective cover which protrude in a direction toward the at least two storage containers when the protective cover is located above the at least two storage containers, and with the at least two storage containers being replaceably disposed in said storage container holder and the piping system including a quick coupling system operating to permit selective fluid coupling and de-coupling of the at least two storage containers with the driving engine without the use of tools.
2. The hand-guided ground compacting machine according to claim 1, wherein the storage container holder comprises at least one of the following features: a) comprises a holding device which is adapted for releasable fixation of the at least two storage containers in the storage container holder; b) comprises a lateral guard which at least partially shields at least one of the two storage containers in its side region from the environment; c) is vibration-cushioned relatively to vibration induced in the machine frame.
3. The hand-guided ground compacting machine according to claim 1, wherein each of said at least two storage containers comprises at least one of the following features: a) said storage container has a maximum filling capacity for liquified petroleum gas (LPG) ranging from 200 ml to 20000 ml; and/or b) said storage container is a cartridge.
4. The hand-guided ground compacting machine according to claim 1, wherein said protective cover has a locking means for arresting said protective cover in a closed position.
5. The hand-guided ground compacting machine according to claim 1, wherein said protective cover has a holding device for fixation of the at least two storage containers in said storage container holder.
6. The hand-guided ground compacting machine according to claim 5, wherein the holding device comprises a resilient pressure applying element which is configured such that said resilient pressure applying element exerts an effective contact pressure on said at least two storage containers in said storage container holder in a closing direction of the protective cover.
7. The hand-guided ground compacting machine according to claim 5, wherein the holding device comprises a retaining and protective sleeve, which in a holding state of the retaining and protective sleeve, comes to bear, at least partially with an end marginal region of the retaining and protective sleeve, against the at least two storage containers.
8. The hand-guided ground compaction machine according to claim 1, wherein in the piping system there is provided, between the at least two storage containers and said driving engine, an evaporator adapted to ensure complete volatilization of the liquified petroleum gas (LPG).
9. The hand-guided ground compacting machine according to claim 8, said evaporator comprises at least one of the following features: a) has a heat input port to which heat is supplied by way of cooling air warmed by the driving engine; b) has a heat input port, to which heat is supplied by way of an oil circulation fed by engine oil; c) is articulated on the ground compacting machine by means of a holder, said holder being vibration-cushioned relatively to vibration induced in the machine frame.
10. The hand-guided ground compacting machine according to claim 1, wherein an external oil cooler is provided for the reduction of the engine oil temperature during operation.
11. The hand-guided ground compacting machine according to claim 1, wherein said hand-guided ground compacting machine comprises at least one of the following features: a) there is provided a tilt switching system comprising a tilt sensor and/or an oil pressure sensor; and/or b) a gas sensor is provided which is adapted to determine a gas concentration in the external environment of said hand-guided ground compacting machine, and an emergency shutdown is provided which switches off said driving engine when said gas sensor detects a predetermined concentration level in the external environment of the hand-guided ground compacting machine.
12. The hand-guided ground compacting machine according to claim 1, wherein an automatic shutdown system is provided which is configured such that said automatic shutdown system permits gas to flow through the evaporator only when there is an adequate negative pressure in the suction pipe of said driving engine, said automatic shutdown system particularly being configured such that it triggers, in a pressure governor, blocking and unblocking of the flow of fuel from the at least one storage container to the driving engine.
13. The hand-guided ground compacting machine according to claim 1, wherein said hand-guided ground compacting machine is a vibration tamper, a vibratory roller or a vibratory plate.
14. The hand-guided ground compacting machine according to claim 2, wherein said cartridge comprises one of a screw valve type cartridge or a bayonet valve type cartridge.
15. The hand-guided ground compacting machine according to claim 1, wherein each of said at least two storage containers holder comprises at least one of the following features: a) said storage container has a maximum filling capacity for liquified petroleum gas (LPG) ranging from 400 ml to 1000 ml; and/or b) said storage container is a cartridge.
16. The hand-guided ground compacting machine according to claim 15, wherein said cartridge comprises one of a screw valve type cartridge or a bayonet valve type cartridge.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The present invention is explained below with reference to the exemplary embodiments illustrated in the figures, in which:
(2) FIG. 1a is a side view of a generic vibratory plate compactor;
(3) FIG. 1b is a side view of a generic vibratory plate;
(4) FIG. 1c is a side view of a generic vibratory roller;
(5) FIG. 2a is a perspective oblique view taken from the right to the front of a vibration tamper powered on liquid gas;
(6) FIG. 2b is a diagrammatic rear view of the vibratory plate compactor shown in FIG. 2a;
(7) FIG. 3 is a perspective detailed diagrammatic view of the guide bar as shown in FIGS. 2a and 2b taken obliquely from the rear right;
(8) FIG. 4 is a detailed diagrammatic view of the attachment means as shown in FIG. 3;
(9) FIG. 5 is an elementary circuit diagram of an attachment means comprising a plurality of storage containers connected in parallel;
(10) FIG. 6 is an elementary circuit diagram of a heat input port to the evaporator fed with engine oil;
(11) FIG. 7 is an elementary circuit diagram of a vacuum switching system; and
(12) FIG. 8 is a diagrammatic drawing of a tilt switching system.
DETAILED DESCRIPTION OF THE INVENTION
(13) Like components are designated in the figures by like reference signs. Recurrent components are not necessarily individually denoted in each figure.
(14) FIG. 1a shows a hand-guided ground compacting machine configured as a vibration tamper 1 comprising a superstructure 2a with a driving engine 3 and a guide bar 4, further having a substructure 2b comprising a compactor base 5 including a ground plate 9 and a transport handle 8. The substructure 2b is linked to the superstructure 2a via a bellows 6. The guide bar 4 on the superstructure 2a and the driving engine 3 are indirectly interconnected via a machine frame 10 or interconnecting console 10. This entire construction is to be understood as the superstructure 2a. Inside the bellows 6, there is disposed a power transmission system, for example, a connecting rod, which converts the rotational driving power of the driving engine 3 to a linear motion and transfers it to the compactor base 5. Between the driving engine 3 and the compactor base 5, there is thus present, in all, a driving transmission 11, which is not described in greater detail and is known per se and by means of which the driving energy of the driving engine 3 is transferred to the compactor base 5. In operation, the compactor base 5 tamps in an approximately vertical direction along the compactor axis S, for example, at a frequency of approximately 10 Hz, over the road subsurface U and compacts the subground material. Guidance of the vibration tamper 1 takes place manually by means of the guide bar 4, which is mounted via resilient damping bearings 7 on the machine frame of the superstructure 2a. The main working direction a is that direction of motion of the vibration tamper under working conditions, in which the compactor axis S is forwardly inclined in relation to the horizontal ground level and in which it automatically moves under working conditions.
(15) FIG. 1b further illustrates the basic construction of a further hand-guided ground compacting machine configured as a vibratory plate 11. The vibratory plate 11 comprises a ground plate 12, on which an exciter unit is arranged which is driven by the driving engine 3 via a belt drive not illustrated in further detail and which induces vibration, and, particularly, at least partially vertical vibration, in the ground plate 12. The driving engine 3 is arranged on the machine frame 10, which in turn is vibration-cushioned in relation to the ground plate 12 via damping elements 13. The vibratory plate 11 also has a guide bar 4, which is articulated to the machine frame 10 in a vibration-cushioned manner via the damping bearings 7.
(16) FIG. 1c shows a vibratory roller 52 as a further example of a hand-guided ground compacting machine. The ground is compacted by means of two drums 53a and 53 b, in the interior of each of which an exciter unit is disposed which is not illustrated in the Figures and which is of a configuration as known in the prior art. The drums 53a and 53b are articulated on the machine frame 10. The drive energy for driving the drums is provided by the driving engine 3. The vibratory roller 52 is guided via the guide bar 4 by an operator walking behind the machine.
(17) The machines illustrated in FIGS. 1a, 1b and 1c are classified as a so-called walk-behind machine, whose overriding common feature resides in the fact that during operation the machine operator is walking behind the machine while guiding the ground compacting machine. Correspondingly, the main working direction a is also the direction of advance counter to the region of the guide bar 4 protruding from the machine.
(18) One aspect of the present invention resides in the fact that the driving engine 3 is one powered by liquid gas. This is further illustrated in FIGS. 2a to 8 with reference to the vibration tamper 1, although the described aspects according to the present invention also apply to a vibratory plate 11 according to the exemplary embodiment as illustrated in FIG. 1b and a vibratory roller 52 according to the exemplary embodiment as illustrated in FIG. 1c, which are explicitly also included within the scope of the present invention. Accordingly, especially the elements arranged on the guide bar 4 of the vibration tamper 1 can also be applied, for example, with the guide bar 4 of the vibratory plate 11 and the guide bar 4 of the roller 52 or at least their machine frames 10. In all cases, the guide bar is preferably vibration-cushioned relatively to the machine frame 10.
(19) FIGS. 2a to 4 illustrate further aspects concerned with the integration of the liquid gas powered driving engine 3 in the vibration tamper 1. In addition to the liquid gas powered driving engine 3 itself, essential elements, particularly of the liquid gas supply system, are storage container holding means 14, such as a storage container holder, storage containers for liquid gas 15, an evaporator/pressure governor system 16, a piping system 17, an attachment means 18, and a protective cover 19.
(20) The liquid gas required for operation of the driving engine 3 is stored in the case of the vibration tamper 1 in the storage containers 15 on the vibration tamper 1 itself. More specifically, in the case of the present exemplary embodiment as shown in FIGS. 2a to 4, the storage containers are two 0.425 kg gas cylinders, which are replaceably disposed in the storage container holding means 14 and directly stand on its base plate 26. As is visible, for example, in FIG. 3, the two gas cylinders 15 are in each case connected to the attachment means 18 via a quick coupler 20, which comprises, in addition to the end connectors 21 directed towards the quick coupler 20, a collecting block 22, the outlet side of which is connected to the piping system 17 leading to the driving engine 3. The two storage containers 15 are thus parallel to each other, so that liquid gas can be drawn from the storage containers 15 towards the piping system 17 simultaneously via the attachment means 18.
(21) The liquid gas coming from the storage containers 15 is initially in a substantially liquid state. However, the driving engine 3 burns the liquid gas in the gaseous state. Between the driving engine 3 and the storage containers 15, there is disposed in the piping system 17, therefore, an evaporator/pressure governor unit 16, to the inlet of which liquid liquefied gas is fed from the storage containers 15 and the outlet of which passes gaseous liquid gas on to the driving engine 3. The evaporator/pressure governor unit 16 is, in the present exemplary embodiment, a coherent component or a multifunctional module, in which an evaporator 23 and a pressure governor 24 are disposed, as described, for example, with reference to FIG. 6.
(22) FIGS. 2a to 3 illustrate, inter alia, the vibration-cushioned mounting of the storage container holding means 14 relative to the machine frame 10. Due to the arrangement of the storage container holding means 14 on the guide bar 4, vibration attenuation of the machine frame 10 relative to the storage container holding means 14 is already achieved by the damping bearings 7 between the guide bar 4 and the machine frame 10. In the present exemplary embodiment, a further damping stage including the damping elements 25 is additionally provided between the guide bar 4 and the storage container holding means 14, so that the storage container holding means 14 is vibration-cushioned relatively to vibration induced in the machine frame 10 via multiple damping stages. The storage container holding means 14 comprise substantially a trough shaped basic body having a base plate 26 and two side walls 27 disposed in the lateral marginal area of the base plate 26 and rising in the vertical direction. By means of said side walls 27, the trough-like storage container holding means 14 are articulated by means of the damping elements 25 to retaining lugs 28 rigidly attached to the guide bar 4. These retaining lugs 28 are connected to the side beams 29 of the guide bar 4. The storage container holding means 14 are in other words connected at two mutually opposing end regions to the guide bar 4 in a vibration-cushioned manner, so that vibration, including that induced in the guide bar 4, is transferred in a damped state to the storage container holding means 14. Particularly, FIG. 3 shows that the storage container holding means 14 are further set at a distance as far as possible from the damping bearings 7 in the direction of the grasping region 30 between the side beams 29 of the guide bar. By this means, the storage container holding means 14 can be implemented as a kind of vibration-balancing counterweight for the purpose of further reducing vibration in the guide bar.
(23) On the storage container holding means 14, there is further provided a lateral guard 31, which supplements the protective action of the heavy-duty and solid-faced side walls 27 towards the rear side of the vibration tamper 1 or towards the machine operator. More specifically, the lateral guard 31 is a transversal strut, which extends between the side walls 27 in the rear region of the storage container holding means 14.
(24) Further protection of the storage containers 15 disposed in the storage container holding means 14 is afforded by the protective cover 19. The protective cover 19 is, more specifically, a protective cover pivotally disposed on a transverse spar 32 of the guide bar, which protective cover is capable of being pivoted down on to the storage containers 15 under working conditions, as shown in FIGS. 2a and 2b and, for example, is capable of being pivoted up for the purpose of replacing the storage container 15, as shown in FIG. 3. In the pivoted up state, the protective cover 19 thus uncovers the storage containers 15 such that they can be easily and simply removed from the storage container holding means 14 or replaced therein. In the pivoted down state, the protective cover 19 prevents damage occurring to the storage container 15 from above and thus also to the regions of the attachment means 18 and of the conduit system 17 that are covered by the protective cover 19. The protective cover 19 also comprises a locking mechanism, specifically comprising, for example, a locking screw 37, by rotation of which the protective cover 19 can be locked in the closed position, as shown in FIGS. 2a and 2b. The locking screw 37 engages for this purpose in a mating counterpart 38 on the storage container holding means 14. This prevents the protective cover 19 from jumping up in an uncontrolled manner under working conditions.
(25) In addition to the substantially solid-faced protective hood, the protective cover 19 further comprises two protective tubes 33, which are disposed on the interior surface of the protective cover 19 and protrude in the direction of the storage container 15. The protective tubes 33 are configured such that, in the pivoted down state of the protective cover 19, they at least partially cover the connecting regions of the valves on the attachment means 18 directed towards the storage containers 15 and surround the sides thereof, so that in this way there is obtained additional protection of this highly sensitive region in terms of safety. For this purpose, a slotted recess is provided in each of the protective tubes, through which recess the connecting means are guided for the purpose of connecting the storage container 15 to the attachment means 18.
(26) Another essential feature of the vibration tamper 1 is the arrangement of the evaporator/pressure governor unit 16 on the guide bar 4 in a likewise vibration-cushioned manner with regard to the machine frame 10 and with regard to the guide bar. Between the evaporator/pressure governor unit 16 (that is, the relevant holding device 36 that serves to hold the evaporator/pressure governor module 16) and the retaining lug 34 on the guide bar 4, there is, thus, likewise present a damping element 35, so that vibration of the guide bars is transferred in a damped manner to the evaporator/pressure governor unit 16.
(27) FIG. 4 illustrates the basic function of the quick couplers 20. These comprise the end connectors 21 disposed on the flexible pipe ends of the attachment means 18. On the storage containers 15, there are provided appropriate coupling counterparts 39 adapted to establish a gastight transfer connection between the storage container 15 and the piping system 17 for the accommodation of the connectors 21. More specifically, the quick coupler 20 is adapted such that a valve will only be opened when a gastight fluid communication route has been established, and the quick coupler 20 will only be released after the relevant valves have been closed. The quick couplers 20 can be coupled and uncoupled by carrying out purely manual pushing and turning movements on the connectors 21 relatively to the coupling counterparts 39, so that no specific tool is necessary for replacing the storage container 15, for example.
(28) FIG. 5 is an elementary circuit diagram and illustrates, in an alternative embodiment to that shown in FIGS. 2a to 4, the parallel arrangement of more than two storage containers 15 in the storage container holding means 14. The storage containers 15 shown in FIG. 5 are, for example, cartridges having a maximum capacity of 1000 ml. The cartridges 15 are connected to the attachment means 18 by means of quick couplers 20 as described above. Each pipe connection between a cartridge 15 and the attachment means 18, is also provided with a stopcock 40 and a check valve 41 mounted down-stream, as regarded in the outflow direction. The check valve 41 substantially serves the purpose of automatically closing the attachment means 18 with respect to the environment when a storage container 15 has been removed from the closing device 18, for example, for the purpose of replacement. Thus, the check valve 41 automatically ensures that the liquid gas present in the other storage containers will not flow out through that connecting arm from which the storage container 15 had been removed. Between the attachment means 18 and the remaining piping system 17 leading to the driving engine 3, there is also provided a central stopcock 42, by means of which the transfer of liquid gas from the storage containers 15 to the driving engine 3 can thus be centrally blocked or unblocked. It goes without saying that the diagram shown in FIG. 5 can be almost arbitrarily extended or reduced to accommodate different numbers of storage containers 15.
(29) To achieve perfect functioning of the liquid gas powered driving engine 3, it is important that the liquid gas be supplied in the gaseous state. In order to make it possible to achieve virtually quantitative volatilization of the liquefied gas, there is disposed between the attachment means 18 and the driving engine 3 in the piping system 17 the said evaporator/pressure governor unit 16 comprising the evaporator 23 and the pressure governor 24. The pressure governor 24 is connected down-stream of the evaporator 23, as regarded in the direction of fluid effluent flow towards the driving engine 3. The essential objective of the pressure governor 24 is to ensure a constant pressure of the gas supplied to the driving engine 3. The pressure governor 24 is an automatically effective pressure governor, which automatically executes the relevant pressure control. The evaporator 23 is intended, on the other hand, to effect complete volatilization of the liquefied gas issuing from the storage containers 15. In the present exemplary embodiment, there is thus provided, for this purpose, means for heating the evaporator 23, in that warmed engine oil is fed to the evaporator 23. For this purpose, there is provided, in the exemplary embodiment illustrated in FIG. 6, an oil pump 43 driven by the driving engine 3, which oil pump pumps warmed engine oil from the engine oil sump 44 towards the evaporator 23 and recycles the same from the evaporator 23 back to the engine oil sump 44. In this evaporator oil circuit 45 there is further disposed a pressure relief valve 46.
(30) FIG. 7 illustrates by way of example the basic modus operandi of an automatic shutdown system for the vibration tamper 1. The automatic shutdown system causes the gas supply to the driving engine 3 to be blocked when the driving engine 3 demands no fuel, or when the driving engine 3 is switched off. The basic principle of the automatic shutdown system illustrated in FIG. 7 involves the fact that an adequate negative pressure predominates in the suction pipe 46 between the carburetor 47 and the driving engine 3 only when a negative pressure is produced in the suction pipe 46 of the driving engine 3 by the rotary movement of the driving engine 3 and the concomitant motion of the piston. For this reason, provision is made for a feedback to be present between the negative pressure in the suction pipe 46 leading to the evaporator/pressure governor unit 16, which feedback permits the transfer of liquid gas through the evaporator/pressure governor unit 16 only when an adequate negative pressure predominates in the suction pipe 46. For this purpose, a pressure signal line 48 is provided between the suction pipe 46 and the evaporator/pressure governor unit 16, by means of which signal line a suitable cut-off device in the evaporator/pressure governor unit 16 is controlled such that an outflow of liquid gas from the evaporator/pressure governor unit 16 to the driving engine 3 is only possible when there is adequate negative pressure in the suction pipe 46.
(31) FIG. 8 finally illustrates the operating principle of a tilt switching system. The essential element of the tilt switching system is a sensor 49, by means of which it is possible to detect at least when a predetermined maximum degree of tilt of the vibration tamper 1 in relation to the horizontal ground level of the road subsurface U has been exceeded. The degree of inclination describes the tilt angle of the compactor axis S of the vibration tamper 1 in relation to a reference perpendicular standing on the ground horizontal. The data ascertained by the sensor 49 are transferred to a control unit 50. When the control unit 50 ascertains that the limit of tilt has been exceeded, it stops the engine. This can take place, for example, by disconnecting the triggering current supply 51 or by comparable measures. Additionally, or alternatively, for example, also shutoff valves or similar measures can be triggered by the control unit 50 in this case, in order to prevent an uncontrolled outflow of liquid gas from a toppled vibration tamper 1.
(32) While the present invention has been illustrated by description of various embodiments and while those embodiments have been described in considerable detail, it is not the intention of Applicant to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will readily appear to those skilled in the art. The present invention in its broader aspects is therefore not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicants' invention.
