GB1563754A

GB1563754A - Balance of reciprocating parts of reciprocating piston machines

Info

Publication number: GB1563754A
Application number: GB4157677A
Authority: GB
Original assignee: Balcke Duerr AG
Current assignee: Balcke Duerr AG
Priority date: 1976-10-15
Filing date: 1977-10-06
Publication date: 1980-04-02
Also published as: BE859659A; AT353389B; ES463204A1; FR2367951B3; DE2646532A1; FR2367951A1; ATA738877A; CH626141A5

Abstract

In order to be able to achieve compensation of the free oscillating inertia forces of the first and second order in a reciprocating piston machine with a reciprocating piston engaging on a crank pin (5) on a crank of a crank shaft (6) via a sliding joint guided in a straight line and a piston rod (4), a balance weight (7) is articulated on the crank shaft (6) symmetrically to the point of engagement of the piston rod (4). The balance weight (7) can be moved in the opposite direction to the reciprocating piston by the crank shaft (6) and its mass and its connecting-rod ratio lambda (quotient of the respective length of the piston rod and the respective crank radius) is matched to the reciprocating piston and the inertia forces of the first and second order, which oscillate with the reciprocating piston. In a preferred compact design, the three-crank crank shaft (6) is mounted on the crank webs (12, 13) associated with the two outer cranks. <IMAGE>

Description

(54) BALANCE OF RECIPROCATING PARTS OF RECIPROCATING-PISTON MACHINES (71) We, BALCKE-DÜRR AG., of 2 Homberger Strasse, D4030 Ratingen, Federal Republic of Germany, a company organized under the laws of the Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a reciprocatingpiston machine of the kind with at least one reciprocating piston acting upon a crankpin on a throw of a crankshaft through a straight-guided crosshead and a connecting rod. It finds application preferably, but not exclusively, as a reciprocating-piston compressor for gases.

Various attempts have been made to balance the oscillating unbalanced forces.

In one arrangement there are two fly weights below the crankshaft, one of which is driven from the crankshaft and the other of which, lying co-axial with the first, rotates in the opposite direction. It involves half-weight or uncompensated gear wheels. Since the fly weights lie coaxially beside one another and have contrary rotation one to the other, their horizontal force components cancel one another. At the same time the fly weights compensate the vertical oscillations of the crankshaft. The compensation transmission only provides a balance of the unbalanced forces of the first order.

It is further known to suppress the disturbing effects of unbalanced forces of the first and second order in the crank drive through a mass balance, that is through a suitable arrangement of counterweights (Leuger, "Lexikon der Technik", Vol. 1, "Principles of Machine Construction" (1960), pages 275 - 280). In the treatment cited formulae are quoted for calculating the torque on the crank and also formulae for the unbalanced forces. There are, however, no precise data for the proportions for overcoming the unbalanced forces through mass balance. The opposed-piston engine cited by way of an example includes a balance piston, which on the one hand leads to an expensive design and on the other also implies the complete balancing of the gas forces as well as the mechanical forces over the whole range of the engine.

On the basis of a reciprocating-piston machine of the kind initially mentioned, it is the object of the invention, while attaining a compact construction, to arrive at a compensation of the free oscillating unbalanced forces of the first and second order.

According to the invention there is provided a reciprocating-piston machine of vertical standing type comprising a reciprocating piston, which engages a crankpin on a throw of a three-throw crankshaft by way of a rectilinearly-guided crosshead and by way of a connecting rod, the crankshaft being mounted on crank webs lying adjacent the two outer throws, a compensated weight connected symmetrically of the engagement point of the reciprocating piston to the two outer crankpins of the crankshaft through the intermediary of connecting rods to move oppositely to the reciprocating piston with its weight matched to the reciprocating piston and to the forces of first and second order which oscillate with the reciprocating piston.

From the support of the crankshaft on the crank webs adjacent the two outer throws the surprising advantage results that the reciprocating-piston machine has an extremely small extent in the direction of the crankshaft. It is well known that for a constant loading the bending of the shaft grows with the third power of the free length between two supporting points. The incorporation of a balance weight must consequently initially appear hazardous because of the possibility of other upsetting forces acting upon the reciprocating piston and taking into account the possibly varying gas forces over the full operating range. With the extremely short free shaft length attained through supporting on the crank webs however, no problems arise. The result is rather a vibrationless running, an economy in foundations, an extension upwards of the running-speed range and consequently a smaller structural bulk and a favourable performance/cost ratio.

The invention will now be described on the basis of one embodiment illustrated in the accompanying drawings, wherein: Fig. 1 is a schematic part section parallel to the crankshaft of a reciprocatingpiston machine, and Fig. 2 is a part section transversely to the crankshaft of the reciprocating-piston machine of Fig. 1, The embodiment relates to a singlecrank, reciprocating-piston compressor of the vertical standing type. Only the components important to the above relationship are illustrated; the further construction of such a single-crank, reciprocatingpiston compressor is known, for example through the Type HTS 230 of the firm of Maschinenbau - AG Balcke, Wormser Strasse 109, 671 Frankenthal/Pfalz, German Federal Republic.

The reciprocating or compressor piston located in the upper part 1 of the machine engages through a knuckle joint 2 with a crosshead bolt 3 and a connecting-rod 4 carried on the crosshead bolt with a central crank journal 5 of a central throw of a crankshaft 6. A balance weight 7 is coupled to the crankshaft 6 through two connecting-rods 10 and 11 pivoting on the two outer crank journals 8 and 9.

The crankshaft 6 is supported on the two crank webs 12 and 13 adjacent the two outer throws of the triple-throw crank shaft 6.

There is also a flywheel 14 on the shaft.

A guiding slide 15 is provided for the balance weight 7 (Fig. 2). The length 11 of the connecting-rod 4 is equal to the length 12 of the connecting-rods 10 and 11.

The balance weight 7 moves in the opposite sense to the reciprocating piston.

If the indicator diagram at any time for the unbalanced forces of the first and second orders is transformed into a time diagram, for instance for a phase of movement between the lower and upper limit positions, then it is shown by superimposition of the associated oscillations that there is a complete compensation.

The corresponding mathematical calculation is obtainable from Lueger (see above).

It can be seen from Fig. 1 that a minimal extension of the machine or the crankshaft in a horizontal direction results through the support on the crank webs 12 and 13.

WHAT WE CLAIM IS: 1. A reciprocating-piston machine of vertical standing type comprising a reciprocating piston, which engages a crankpin on a throw of a three-throw crankshaft by way of a rectilinearly-guided crosshead and by way of a connecting rod, the crankshaft being mounted on crank webs lying adjacent the two outer throws a compensating weight connected symmetrically of the engagement point of the reciprocating piston to the two outer crankpins of the crankshaft through the intermediary of connecting rods to move oppositely to the reciprocating piston with its weight matched to the reciprocating piston and to the forces of first and second order which oscillate with the re c iprocating piston.

2. A reciprocating-piston machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. free length between two supporting points. The incorporation of a balance weight must consequently initially appear hazardous because of the possibility of other upsetting forces acting upon the reciprocating piston and taking into account the possibly varying gas forces over the full operating range. With the extremely short free shaft length attained through supporting on the crank webs however, no problems arise. The result is rather a vibrationless running, an economy in foundations, an extension upwards of the running-speed range and consequently a smaller structural bulk and a favourable performance/cost ratio. The invention will now be described on the basis of one embodiment illustrated in the accompanying drawings, wherein: Fig. 1 is a schematic part section parallel to the crankshaft of a reciprocatingpiston machine, and Fig. 2 is a part section transversely to the crankshaft of the reciprocating-piston machine of Fig. 1, The embodiment relates to a singlecrank, reciprocating-piston compressor of the vertical standing type. Only the components important to the above relationship are illustrated; the further construction of such a single-crank, reciprocatingpiston compressor is known, for example through the Type HTS 230 of the firm of Maschinenbau - AG Balcke, Wormser Strasse 109, 671 Frankenthal/Pfalz, German Federal Republic. The reciprocating or compressor piston located in the upper part 1 of the machine engages through a knuckle joint 2 with a crosshead bolt 3 and a connecting-rod 4 carried on the crosshead bolt with a central crank journal 5 of a central throw of a crankshaft 6. A balance weight 7 is coupled to the crankshaft 6 through two connecting-rods 10 and 11 pivoting on the two outer crank journals 8 and 9. The crankshaft 6 is supported on the two crank webs 12 and 13 adjacent the two outer throws of the triple-throw crank shaft 6. There is also a flywheel 14 on the shaft. A guiding slide 15 is provided for the balance weight 7 (Fig. 2). The length 11 of the connecting-rod 4 is equal to the length 12 of the connecting-rods 10 and 11. The balance weight 7 moves in the opposite sense to the reciprocating piston. If the indicator diagram at any time for the unbalanced forces of the first and second orders is transformed into a time diagram, for instance for a phase of movement between the lower and upper limit positions, then it is shown by superimposition of the associated oscillations that there is a complete compensation. The corresponding mathematical calculation is obtainable from Lueger (see above). It can be seen from Fig. 1 that a minimal extension of the machine or the crankshaft in a horizontal direction results through the support on the crank webs 12 and 13. WHAT WE CLAIM IS:

1. A reciprocating-piston machine of vertical standing type comprising a reciprocating piston, which engages a crankpin on a throw of a three-throw crankshaft by way of a rectilinearly-guided crosshead and by way of a connecting rod, the crankshaft being mounted on crank webs lying adjacent the two outer throws a compensating weight connected symmetrically of the engagement point of the reciprocating piston to the two outer crankpins of the crankshaft through the intermediary of connecting rods to move oppositely to the reciprocating piston with its weight matched to the reciprocating piston and to the forces of first and second order which oscillate with the re c iprocating piston.