EP0569790B1 - Lubrication circuit for engines with crank drive - Google Patents

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 (GB-A-2 006 390).

In known lubrication circuits of machines with a crank mechanism, the supply and distribution of the pressure lubricant is usually carried out through 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 head directed. 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 fed 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 is in the area of the greatest pressure losses, the risk of malfunctions in 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. This is achieved by designing the main lubrication channel in accordance with the characterizing part of claim 1.

In the crosshead guides at the transitions of the central lubrication channel into the cavities of the crosshead journals, 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 a crankshaft 4 is rotatably mounted in main bearings 41 at the end parts thereof. 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, e.g. B. is connected via a pressure pump 7 and a filter 8. In the outlet side leading to a collecting container there is a regulator 9 for controlling the lubricating oil flow, e.g. B. with an overflow valve provided.

und gleichzeitig eines der Verhältnisse $$\text{d = D > 0,5 L, \hspace{1em}\hspace{1em}\hspace{1em}d > D > 0,25 L}$$

gilt.The cross section of the central lubrication channel 6 is designed 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, with 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 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. Appropriately, the journals 31 can - 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 (3)

1. A lubrication circuit of the machines with a crank mechanism especially of the plunger and piston pumps where in a crankcase (1) and least one crosshead (3) provided with a crosshead pin (3) is placed in a moveable position in a crosshead guide (101) and connected by means of a rod (5) to a crankshaft (4) which is placed in the crankcase (1) by main bearings (41) and where the lubrication circuit is represented by one central lubricating through-channel (6) placed in the crankcase (1) in the crosshead pin middle stroke (31) normal to the crosshead guide longitudial axis (101) where the rod lubricating channels (62) for the rod bearings (51) and the crosshead pin (31) lubricating channels (63) for the pin bearings (32) are branching off and where in the crosshead (3) pin (31) at least one axial through-hollow (311) is formed which is during the crosshead (3) stroke connected all the time with the central lubricating channel (6) and due to it the lubricant flow channel is formed characterized by the fact that the through-channels (61) for the main bearings (41) of the crankshaft (4) branchig off the lubricating channel (6) in the crankcase (1) and that the central lubricating chanel (6) is formed in such a way that the following relations are given for its diameter (D) compared to the hollow (311) diameter (d) of the crosshead pins (31) and the stroke lenght (L) of the crosshead (3) $$\text{L < d + D}$$

   

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

   
2. The lubrication circuit according to the claim 1 is characterized by the fact that in the transition points in the central lubricating channel (6) in the hollow (311) of the crosshead pins (31) in the crosshead guide (101) hemi-closed half-ring grooves (102) are placed.
3. The lubrication circuit according to the claims 1 or 2 is characterized by the fact that the central lubrication channel (6) at the crankcase (1) outlet is provided with a lubricant flow controller (9).

Images