EP0569790A1 - Lubrication circuit for engines with crank drive - Google Patents

Abstract

The subject of the invention is a lubrication circuit for machines with crank drive, especially plunger and piston pumps in which in a crankcase (1) at least one crosshead (3) provided with a crosshead journal (31) and a connecting rod (5) is supported so that it can slide in a crosshead guide (101). The connecting rod (5) is coupled by way of a connecting rod bearing (51) to the crankshaft (4) supported in main bearings (41) in the crankcase (1). In the crankcase (1) a single through lubrication duct (6) running perpendicular to the longitudinal axis of the crosshead guide (101) is formed in the middle area of the crosshead stroke. Perpendicular to the axis of the said duct, feed lubrication ducts (61) to the main bearings (41) are formed in the crosshead guide (101) of the crankcase (1), connecting rod lubrication ducts (62) in the connecting rod (5) and journal lubricating ducts (63) in the crosshead journal (31). The main lubricating duct (6) is so designed that the ratio L < d + D and at the same time one of the ratios d = D > 0.5 L, d > D > 0.25 L applies to its diameter (D) compared to the diameter (d) of the hollow chamber (311) of the crosshead journal (31) and the stroke length (L) of the crosshead journal (3). <IMAGE>

Description

The invention relates to a lubrication circuit of machines with a crank mechanism, in particular plunger and piston pumps for the high-pressure delivery of working media, of the type specified in the preamble of claim 1.

In known lubrication circuits of machines with a crank mechanism, the supply and distribution of the pressure lubricant is generally carried out via bores in the crankshaft. From here, the oil becomes the main and connecting rod bearings, and with the help of another hole in the connecting rods, the Phillips headed. A separate branch of the lubrication circuit is provided for the lubrication of the actual crossheads or an oil mist is generated, which makes a collecting space for the oil above the crossheads necessary.

A lubrication system is known from CS-A-212 094, in which the pressure lubricant is supplied via a separate branch of the lubrication circuit to the outer circumference of the cross head provided with grooves for the piston rings on its edges. The crosshead has a longitudinal groove on its outer circumference, which is connected to the transverse opening for the crosshead pin.

The disadvantages of the known lubrication circuit systems include the difficult machining of the lubrication openings in the crankshaft and the need for an additional distribution of the lubricant to the crossheads. Another problem is the cyclically interrupted supply of the lubricant into the joint of the cross-head journal bearing due to the arrangement of the lubrication paths between the rotating crankshaft and the bore in the connecting rod for the supply of the lubricant. Since the most stressed assembly of the cross-head journal bearing at the end of the lubrication paths lies in the area of the greatest pressure losses, the risk of malfunctions of the crank mechanism increases.

The object of the invention is to provide a lubrication system for machines with a crank mechanism, which eliminates the disadvantages mentioned above. The lubrication circuit according to the invention is for machines with a crank mechanism, in particular of plunger and piston pumps, in which at least one cross head provided with a cross head pin and a connecting rod is slidably mounted in the crosshead guide in the crankcase. The connecting rod is connected to the crankshaft in the crankcase in main bearings via a connecting rod bearing. The essence of the invention is that a single continuous lubrication channel is formed in the crankcase at the central position of the crosshead pin perpendicular to the longitudinal axis of the crosshead guide, with supply line lubrication channels for the main bearings in the crosshead guide of the crankcase, in the connecting rod connecting rod lubrication channels and in Cross head journals are provided.

und gleichzeitig eines der Verhältnisse

$\text{d = D > 0,5 L, d > D > 0,25 L}$

gilt.The main lubrication channel is designed so that the ratio for its diameter D compared to the diameter d of the cavity of the cross-head pin and the stroke length L of the cross pin

$\text{L <d + D}$

and at the same time one of the relationships

$\text{d = D> 0.5 L, d>D> 0.25 L}$

applies.

In the crosshead guides at the transitions of the central lubrication channel into the cavities of the crosshead pins, semi-closed semicircular grooves and at the outlet are advantageous the crankcase, the central lubrication channel is provided with a flow regulator of the lubricant.

The lubrication circuit according to the invention enables reliable pressure lubrication of the crossheads with the lubricant, which is then conveyed under pressure to the next lubrication points and spaces via simplified, shortened and generously dimensioned lubrication paths. The construction according to the invention enables the bearing gap of the cross-head journal to be constantly filled with lubricant without interruptions and pressure pulsations during the rotation of the crankshaft. The supply of the lubricant to all pressure lubrication points is carried out by a single central lubrication channel, the crankshaft being not interrupted by any lubrication holes, which considerably simplifies their manufacture and processing.

Fig. 1

einen Schnitt durch das Kurbelgehäuse mit einem Kurbeltrieb in der Ebene des zentralen Schmierkanals;

Fig. 2

einen Teilausschnitt einer halbrunden Nut am Durchgang des Schmierkanals durch die Kreuzkopfführung; und

Fig. 3

das Verhältnis und die Anordnung des zentralen Schmierkanals und des Hohlraumes des Kreuzkopfzapfens in Bezug auf den Kreuzkopfhub.

Further advantages and special features of the invention result from the following description of preferred exemplary embodiments with reference to the drawing. Show it:

Fig. 1

a section through the crankcase with a crank mechanism in the plane of the central lubrication channel;

Fig. 2

a partial section of a semicircular groove at the passage of the lubrication channel through the crosshead guide; and

Fig. 3

the ratio and arrangement of the central lubrication channel and the cavity of the crosshead pin in relation to the crosshead stroke.

As can be seen from FIG. 1, a plurality of crosshead guides 101 are formed in a crankcase 1 provided with a trough 2, in which a plurality of crossheads 3 of the crank mechanism are slidably guided and on the end parts of which a crankshaft 4 is rotatably mounted in main bearings 41. Each crosshead 3, which is fixedly connected to a piston rod, has two lateral projections which delimit a central cutout for receiving a connecting rod head 52. A high bearing journal 31 is fixed in aligned transverse bores of the two approaches, on the central part of which the connecting rod head 52 is mounted via a slide bearing 32. Each connecting rod is rotatably supported in a bearing 51 on the crankshaft 4. In a central portion of the stroke of the crosshead pin 31 a continuous central lubrication channel 6 is formed in the crankcase 1 perpendicular to the longitudinal axis of the crosshead guides 101, which passes through the intermediate walls of the crosshead guides 101 and to a lubricant source 7 arranged outside the crankcase 1, z. B. is connected via a pressure pump 7 and a filter 8. In the outlet side leading to a collecting container is a controller 9 for controlling the lubricating oil flow, for. B. with an overflow valve provided.

und gleichzeitig eines der Verhältnisse

$\text{d = D > 0,5 L, d > D > 0,25 L}$

gilt.The cross section of the central lubrication channel 6 is formed in relation to the respective cavity 311 in the crosshead pin 31 so that the flow areas overlap in each stroke position of the crosshead 3, the diameter D of the central lubrication channel 6 compared to the diameter d of the respective cavity 311 of the crosshead pin 31 and the length L of the stroke of the crosshead 3 the ratio

$\text{L <d + D}$

and at the same time one of the relationships

$\text{d = D> 0.5 L, d>D> 0.25 L}$

applies.

Perpendicular to the axis of the central lubrication channel 6, supply line lubrication channels 61 to the main bearings 41 of the crankshaft 4 are formed in the crosshead guides 101, lubrication channels 62 to the connecting rod bearings 51 in the connecting rods 5 and 31 lubrication channels 63 to the connecting rod bearings 32 in the crosshead pins 31. The inlets and outlets of the sections of the central lubrication channel 6 in the crosshead guides 101 are, for. B. expanded by semi-closed semicircular grooves 102, which are shown in Fig. 2.

In operation, pressure oil is passed from the source 7 via the filter 8 into the central lubrication channel 6 and from here via the corresponding vertical lubrication channels 61, 62, 63 to the individual lubrication points of the crank mechanism. The flow controller 9 is set so that a constant and uninterrupted supply of lubricant to both the exposed coupling points of the connecting rod 5 with the crosshead 3 as well as to the main bearing 41 of the crankshaft 4 and the connecting rod bearing 51 is ensured.

The recorded execution is not the only possible solution according to the invention. Thus, with a favorably chosen ratio of the sizes d, D, L and thus ensuring a sufficient overlap of the central lubrication channel 6 and the cavity 311 of the crosshead pins 31, the formation of a semi-closed semicircular groove 103 is unnecessary in each layer phase of the crosshead 3. Furthermore, the central lubrication channel 6 can also have an elongated cross section in order to ensure sufficient overlaps even with longer stroke lengths of the pistons. Furthermore, instead of the axially continuous cavity 311, a plurality of axial bores can also be formed in the bearing journal 31, which communicate with the lubrication channels 62 and 63. The bearing journals 31 can also expediently - as shown - be slightly shorter than the transverse bores in the cross heads 3 of the pistons, which results in end-side inlet and outlet chambers for the lubricating oil in and out of the cavities 311. Finally, the regulator 9 with its overflow valve can be replaced by another type of fitting or by an exchangeable or adjustable throttle.

The lubrication circuit according to the invention can be used in all crank drives in which a constant and uninterrupted supply of the pressure lubricant to all lubrication points must be ensured.

Claims (4)

Lubrication circuit of machines with a crank mechanism, in particular of plunger and piston pumps, in which at least one cross head (3) provided with a bearing pin (31) and a connecting rod is slidably mounted in a cross head guide (101) in the crankcase and the connecting rod on a in the crankcase (1 ) is supported by means of main bearings (41) mounted crankshaft (4),
characterized,
that in the crankcase (1) in a central portion of the stroke of the cross pin (31) a perpendicular to the longitudinal axis of the cross head guide (101) is formed a continuous lubrication channel (6), of which in the cross head guide (101) of the crankcase (1) extending lubrication channels (61) for the main bearings (41) of the crankshaft (4), in the connecting rod (5) extending lubrication channels (62) for the connecting rod bearings (51) and in the bearing journal (31) extending lubrication channels (63) for the journal bearings (32) , and that in the bearing journal (31) of the crosshead (3) at least one axially continuous cavity (311) is formed, which during the lifting movement of the crosshead (3) constantly communicates with the central lubrication channel (6) and forms a flow channel for the lubricant. Lubrication circuit according to claim 1,
characterized,
that the central lubrication channel (6) is designed so that for its diameter (D) compared to the diameter (d) of the cavity (311) of the cross-head pin (31) and the stroke length (L) of the cross-pin (3) the ratio

$\text{L <d + D}$

and at the same time one of the relationships

$\text{d = D> 0.5 L, d>D> 0.25 L}$

applies. Lubrication circuit according to claim 1 or 2,
characterized,
that semi-closed semicircular grooves (102) are formed in the crosshead guides (101) at the transition points of the central lubrication channel (6) into the cavities (311) of the crosshead pins (31). Lubrication circuit according to claims 1 to 3,
characterized,
that the central lubrication channel (6) at the outlet from the crankcase (1) is provided with a flow regulator (9) of the lubricant.

Images