HK1081253B - Positive-displacement reciprocating compressor - Google Patents

Description

Positive displacement reciprocating compressor

Technical Field

The present invention relates to a reciprocating compressor of the positive-displacement type, suitable for various applications, such as for example for supplying spray guns or tools of the type using compressed air, in order to carry out blowing operations in machine shops or in other cases.

Background

It is known that, in order to obtain the compressed air required for carrying out operations such as painting of industrial products, such as automobiles or earthmoving machines, positive displacement reciprocating compressors are used, in which the compression is carried out at different air flow rates, depending on the requirements of the application.

Such compressors typically include a piston or plunger that slides within a cylinder, which compresses air drawn from the surrounding environment to be provided at a higher pressure to one or more users.

It is known to those skilled in the art that a piston reciprocates within a cylinder.

The movement of the piston is obtained by means of a so-called "oscillating piston" mechanism, which is well known to the person skilled in the art.

The compressed air produced by the compressor is typically stored in a tank for later use.

However, such compressors have certain known inconveniences.

A first inconvenience consists in the fact that, due to the fixed nature of the "oscillating piston" mechanism, the sealing elements or gaskets associated with this piston are subjected to stresses that cause considerable wear.

This is due to the continuous, irregular oscillation of the piston within the cylinder, which results in excessive rubbing of the sealing element against the inner wall of the cylinder.

Therefore, disturbances in maintenance or replacement of the sealing element are necessary, which involves unavoidable material and labor costs.

A second inconvenience consists in the fact that, in order to limit the wear of the sealing element, the oscillating piston performs an incomplete stroke inside the cylinder.

As a result, the production of compressed air is low and the efficiency of the compressor is low relative to what is possible and desirable.

Another inconvenience is its high degree of structural complexity.

Another inconvenience is that the above-mentioned prior art compressors do not produce a continuous flow of compressed air when in operation.

It is known that this fact leads to undesired operating conditions in which the compressed air leaves the compressor intermittently and the operations that have to be carried out are carried out in an imprecise and insufficient manner.

In order to overcome the latter inconvenience, compressors of the known type are provided with a storage tank in which the compressed air is stored before use.

The capacities of the tanks available on the market today range from about 25 to 5000 litres and can have a variety of applications depending on the industrial application.

Only after these tanks are completely filled, the compressed air can be used stably and conveniently.

The flow of compressed air provided by the compressor makes it possible to obtain a continuous flow and, in use, optimal working conditions for correctly performing the operation.

However, the known type of solution also has a first inconvenience due to the fact that the tank considerably increases the overall dimensions of the compressor, which is particularly important in applications where ease of movement and practicality of operation of the compressor are required.

Another inconvenience is the danger involved with the presence of the can.

Another inconvenience is the need to provide more compressed air than actually needed in each application.

In fact, when the compressor is shut down, it is necessary to refill the tank with its nominal flow rate in order to be effective for subsequent use.

This involves an extra series of operations and an avoidable energy loss.

A further inconvenience is that the arrangement of the tank also makes the structural shape of the compressor more complex.

Disclosure of Invention

The present invention aims to overcome the inconveniences described above.

The main object of the present invention is in particular to provide such a compressor in which the movement of the piston causes a reduction in the degree of wear involved with the sealing elements, compared to corresponding known compressors.

A second object is to improve the efficiency of the positive displacement compressor with respect to the prior art.

Another object of the present invention is to supply a continuous and steady flow rate of compressed air to the user, so as to simplify the constructive shape of the compressor with respect to known compressors.

Said object is achieved by means of a reciprocating compressor of the positive-displacement type provided by the present invention, comprising at least one plunger slidably coupled in a cylinder in which a compression chamber is formed and which is operatively connected to a drive means for moving the plunger in the cylinder, characterized in that the drive means comprise a motor having a rotary shaft coupled to an eccentric which is mechanically connected to the plunger and which can force the plunger to displace longitudinally in a perpendicular direction with respect to the axis of rotation of the rotary shaft, the eccentric comprising a substantially longitudinally extending rotary body in which a tubular portion is coupled to the shaft on one side and an eccentric pin is formed on the other side, characterized in that the eccentric pin is provided with contrast means for cooperation with a connecting rod and an upper bracket member, the connecting rod being fastened to a lower bracket member, the upper bracket member supports the plunger.

According to a preferred embodiment of the invention, the compressor comprises a shaped base which supports the piston and in which a collecting chamber for the compressed air is formed, which is provided with at least one inlet for the compressed air in order to communicate with the compression chamber of the cylinder and with at least one outlet for the compressed air in order to be connected using equipment.

Advantageously, the movement of the plunger within the cylinder is an axial movement so as to be fully guided along the longitudinal axis of the cylinder containing the plunger.

This minimizes the wear of the sealing elements interposed between the piston and the respective cylinder, which increases the life of the same relative to the wear that occurs in known types of compressor.

Advantageously, this axial movement brings the plunger to the end of the stroke within the cylinder, which increases the production of compressed air and therefore the efficiency of the compressor with respect to the compressors of the prior art.

Advantageously, the compressor of the present invention produces a more continuous flow of compressed air in use than prior art compressors and does not require a tank of suitable capacity to be associated with the compressor.

This aspect is further improved by the arrangement of the collection chamber, which, despite the reduced size, contributes to a substantially continuous air flow rate in use.

As will be described in detail below, the collecting chamber compensates for the interruption of the minimum compressed air supply during start-up and operating conditions.

Moreover, when the compressor is not operating, the collection chamber can be refilled quickly, presumably taking several seconds to achieve this operation.

In this way, the energy consumption of the compressor of the invention in the tank associated with the stable refilling of compressed air is negligible once the use is over, compared with the corresponding type of compressor of the prior art.

All the advantages are obtained without a storage tank, which is required in the prior art.

In this way, the overall size and structural complexity of the compressor is significantly reduced compared to the prior art.

Moreover, handling, transport and arrangement of the compressor can be improved in any case.

In addition, in an advantageous manner, the risk of the compressor of the invention is reduced compared to the compressors with the tank of the prior art.

Drawings

The above objects, advantages and other aspects of the present invention will be better understood with reference to the following illustrative description of a non-limiting preferred embodiment in conjunction with the accompanying drawings, in which:

FIG. 1 is a partially sectioned isometric view of the compressor of the present invention;

FIG. 2 is an isometric view of a first detail of the compressor shown in FIG. 1;

FIG. 3 is an isometric view of a second detail of the compressor shown in FIG. 1;

FIG. 4 is an isometric view of a third detail of the compressor shown in FIG. 1;

FIG. 5 is an isometric view of a detail of the compressor shown in FIG. 4;

FIG. 6 is an isometric view of a fourth detail of the compressor shown in FIG. 1;

FIG. 7 is a bottom isometric view of a detail of the compressor shown in FIG. 6;

FIG. 8 is a partially sectioned isometric view of a fifth detail of the compressor shown in FIG. 1;

FIG. 9 is an isometric view of a detail of the compressor shown in FIG. 8 in an operational condition, i.e., a compression stroke;

FIG. 10 is an isometric view of a detail of the compressor shown in FIG. 9 in another operating condition, i.e., the suction stroke;

FIG. 11 is an isometric view of a different embodiment of the detail shown in FIG. 3;

FIG. 12 is an isometric view of a detail of the compressor shown in FIG. 11;

FIG. 13 is an exploded isometric view of a second detail of the compressor shown in FIG. 11; and

fig. 14 is an isometric view of a different embodiment shown in fig. 1.

Detailed Description

In figure 1 there is shown a positive displacement reciprocating compressor of the present invention, generally designated by the reference numeral 1.

It can be seen that the compressor comprises four plungers, indicated by the reference numbers 2, 3, 4, 5, slidingly associated in respective cylinders, indicated by the reference numbers 6, 7, 8, 9, of which only the cylinders 8 and 9 can be seen and the compression chambers, indicated by the reference numbers 8a and 9a, are obtained.

The plungers 2, 3, 4, 5 are operatively connected to a drive means, generally designated by the reference numeral 10, which moves them in the respective cylinders 6, 7, 8, 9.

According to the invention, the drive means 10 comprise a motor 11 having a rotary shaft 12 connected to eccentric means generally designated by reference numeral 13, which are mechanically connected to the plungers 2, 3, 4, 5 and can force the plungers to move longitudinally in a vertical direction with respect to the axis of rotation Y of the rotary shaft 12.

In fig. 1, it can also be seen that the positive displacement compressor 1 comprises a shaped base 31 supporting the plungers 2, 3, 4, 5.

As shown in fig. 2, the eccentric 13 comprises a substantially longitudinally extending rotating body in which a tubular portion 14 is obtained on one side for connection with the shaft 12, for example a keyed coupling, well known to a person skilled in the art.

On the opposite side of the rotating body, an eccentric pin 15 is obtained, provided with contrast means, generally indicated by the reference numeral 16, which, in this particular case, as will be described in detail below, are arranged so as to cooperate with formations 17, 18, as shown in figure 3, formed in respective bracket members 19, 20 that support a pair of plungers 2, 4 and 3, 5.

According to another embodiment of the invention, not shown, the volumetric compressor may comprise a different number of plungers and corresponding cylinders, which number may vary continuously from one to a plurality and may be set by the manufacturer, depending on the compressed air flow rate that must be obtained and structurally feasible for the user.

There are therefore also different embodiments of the compressor of the invention, which comprise plungers supported by a bracket member, or a pair of mutually opposite and coaxial plungers supported by a single bracket member, or another pair of plungers supported by respective bracket members, staggered at right angles to each other, etc.

It can also be seen in fig. 2 that the rotating body is provided on the outside with a shaped sleeve portion 21 coaxial with the tubular portion 14 in order to balance the weight of the tubular portion 14 with respect to the eccentric pin 15 during rotation of the rotating body.

Fig. 3 shows in detail that the first bracket part 19 has a shaped element 17 and supports a first pair of mutually facing and coaxial plungers 2 and 4, while the second bracket part 20 has a shaped element 18 and supports a second pair of mutually facing and coaxial plungers 3 and 5.

Contrast device 16 comprises a pair of cams 22 and 23 arranged one above the other and coaxial to each other and to eccentric pin 15.

The first cam 22 cooperates with the profile 17 of the first bracket element 19, while the second cam 23 cooperates with the profile 18 of the second bracket element 20.

As can be seen in fig. 3 and 4, the formations 17 and 18 receiving the contrast device 16 preferably, but not necessarily, comprise through openings and the structural means are not incorporated in the present invention as the formations may have any form of shape.

The first bracket member 19 and the second bracket member 20 are arranged perpendicularly to each other and they slide one over the other so as to define a so-called "star" configuration, as shown in figures 3 and 4.

The longitudinal axes Z1, Z2 defined by the first and second pairs of plungers 2, 4 and 3, 5, respectively, lie in the sliding plane between the first frame member 19 and the second frame member 20 such that the center of each plunger 2, 3, 4, 5 lies on the same virtual circle C as shown in fig. 4.

Fig. 4 shows each profile 17 and 18 with a pair of wear-resistant inserts 24, 25 and 26, 27 facing each other, which are applied to the lateral edges 17a and 18a of the profiles 17 and 18.

The wear resistant inserts 24, 25 and 26, 27 are in this case made of abrasive steel, but in other embodiments they may be made of a suitable material for such components, such as Teflon.

The use of the above materials allows to obtain a proper contact between contrast means 16 and lateral edges 17a and 18a of each profile 17, 18 during rotation of the rotating body, which on the one hand provides a good durability of the mechanical elements in the reciprocating movement.

As can be seen in fig. 5, the plunger 5 is provided with a peripheral sealing element 28 which protrudes from the lateral edge 5a of the plunger 5 and is stably held in position by a covering disc 29, the covering disc 29 being mounted in a recess on the outer wall of the plunger 5.

The cover disc 29 is integral with the plunger 5 by means of first fastening means, generally designated by the reference numeral 30 and of a known type, for example screws.

As shown in fig. 6, according to the preferred embodiment of the invention described herein, the compressor 1 comprises a collection chamber 32 for the compressed air, which is formed in the above-mentioned shaped base 31 and is provided with four compressed air inlets, of which only two are visible, which are designated by the reference numerals 33 and 34.

The collecting chamber 32 communicates with the compression chambers belonging to each cylinder 6, 7, 8, 9, of the type indicated in figure 1 by the reference numerals 8a and 9 a.

The collection chamber 32 is also provided with a compressed air outlet, not shown in the drawings, which communicates with the outside and preferably has an annular shaped configuration.

Each inlet is provided with a valve 35 comprising a steel annular foil, the shape of which corresponds significantly to the shape of the collection chamber 32 and thus acts as a unique valve for each inlet.

Moreover, in the operating condition, described in detail below, the valve 35 is open at the moment when one plunger 2, 3, 4, 5 is compressed, and it is closed when the same plunger 2, 3, 4, 5 draws in air in the opposite direction at the same moment.

The shaped base 31 is provided with a closing cover 36 applied thereto for closing the collection chamber 32 by means of connection means, not shown in the drawings and known in the art, for example screws.

The configuration and shape of the collection chamber 32 is advantageous and effective for providing more stable compressed air in a continuous manner during use.

In fact, if the sequential movement of the plungers 2, 3, 4, 5 provides, on the one hand, a nearly optimal flow of compressed air which is at least more continuous with respect to the corresponding compressors of known type and, on the other hand, minimizes the discontinuous flow at the compressed air outlet, which is compensated in an optimal way by the collection chamber 32.

As will be described below, the action of the plungers 2, 3, 4, 5 in combination with the collection chamber 32 provides, in use, an optimal operating condition of the compressor 1, since the flow rate is continuous, fluid and stable.

As shown in fig. 8, the compressor 1 comprises four head covers, generally indicated by 37, 38, 39, 40, each applied externally to the shaped base 31 by means of second fastening means, generally indicated by 41, so as to be arranged to cover a respective cylinder 6, 7, 8, 9.

Each head 37, 38, 39, 40 has two through holes, partially shown in fig. 8 for the heads 39, 40, respectively indicated by 42, 44, predisposed to suck the air to be compressed inside the cylinders 6, 7, 8, 9.

In the following fig. 9 and 10, the structural details are shown in detail only with reference to the head 40, the other heads 37, 38, 39 also having the same features.

In the above figures, the two through holes which suck in the air to be compressed are indicated by the reference numerals 42 and 43.

The compressor 1 comprises flexible thin blades 45, preferably made of steel, which are coupled to the inner walls 40a of the head 40, the inner walls 40a being turned towards the respective cylinder 9.

The flexible thin vane 45 is blocked at the ends 45a, 45b by bringing the peripheral edge 9b of the cylinder 9 close to the cylinder head 40.

Flexible thin blades 45 are provided adjacent the through holes 42 and 43 to close the through holes during the compression stroke and open the through holes during the suction stroke.

The flexible thin blade 45 is therefore provided at the ends 45a, 45b with a pair of notches coupled with respective pins applied to the inner wall 40a of the head 40.

During the suction stroke, the flexible thin blade 45 is bent towards the inside of the cylinder 9, substantially away from the inner wall 40a of the head 40 for the majority of its length, the other parts being connected only at the ends 45a, 45 b.

This is possible because the notches formed at the ends 45a, 45b of the flexible thin blade 45 slidingly retain the respective pins so that a portion sufficiently separates the thin blade 45 from the inner wall 40a of the head 40, which allows the air to enter the cylinder 9.

It is evident that such an air suction system is very simple to manufacture, since it does not require the fastening means normally used in the prior art to connect such structural details to each other in compressors.

An example of a different embodiment of the invention is shown in figure 11, in which the positive displacement reciprocating compressor differs from the one described above, in that a contrast device, generally indicated with 105, is associated with the eccentric pin 104 of the eccentric 100, which eccentric pin 104 cooperates, as clearly shown in figure 13, with a connecting rod 106, which is fastened to a lower bracket member 107 and an upper bracket member 108, which support a pair of plungers 101, 102 facing and coaxial with each other.

The lower bracket piece 107 and the upper bracket piece 108 are parallel to and spaced apart from each other and are coupled at their peripheral edges 101a, 102a to the plungers 101, 102.

Fig. 13 shows the head portion 106a of the connecting rod 106 engaging a through opening 109 formed in the lower bracket member 107, while the small end 106b of the connecting rod 106 is coupled by means of a ball bearing therebetween to a pin 110 which is connected to the lower bracket member 107 and the upper bracket member 108.

In this case, therefore, the rotary motion of the shaft 103 and of the eccentric pin 104 associated therewith is transformed into a reciprocating rectilinear motion by means of a mechanism known in the art by the term "crank-link assembly".

Fig. 14 below shows another embodiment of the invention, in which the positive displacement compressor, generally designated by the reference numeral 200, comprises a handle means 203 for the user, which is connected to a shaped base 202.

In this compressor 200, the collection chamber 204 of the compressed air comprises a tubular structure which defines and protects, on the outside, the driving device 201 and the shaped base 202.

In this case, the compressor 200 also comprises two wheels connected to the shaped base 202 for the actual handling by the user, only one wheel being shown in the figures, indicated by reference numeral 205.

In operation, the drive means 10 produce a movement of the eccentric 13 coupled to the frame parts 19, 20 on which the plungers 2, 4 and 3, 5 are mounted in pairs and facing each other.

It is now assumed, for example, that the eccentric 13 initially moves the plunger 2 in the profile 17 of the bracket member 19, which plunger performs an air compression stroke in the cylinder 6.

Subsequently, the plunger 4, which is diagonally opposed to and integral with the plunger 2, simultaneously starts an intake stroke to draw air into the cylinder 8.

The following stroke is performed due to the fact that the flexible thin blade, only one of which is shown in the figure and indicated by reference numeral 44, is moved almost completely away from the inner wall of the cylinder head 39 during the suction stroke in order to let air in through the two through holes, the blade not being shown in the figure but indicated by reference numeral 45.

The plunger 3 is adjacent to the plunger 2 and is arranged with its longitudinal axis Z2 perpendicular to the longitudinal axis Z1 of the plunger 2, as the eccentric 13 moves within the profile 18 of the bracket member 20, the plunger 3 starts to compress within the cylinder 7 with a small air flow rate even before the plunger 2 completes its compression stroke within the cylinder 6.

Similar to the description of the plunger 4, when the plunger 3 starts to compress air, the plunger 5 diagonally opposite and integral with the plunger 3 draws in a small amount of air in the cylinder 9.

In this way, when the plunger 2 has completed its compression operation, the plunger 3 adjacent thereto has started to compress its own amount of air.

In a sequential and uninterrupted manner, the eccentric 13 sequentially moves the plungers 4 and 5 so that they can generate compressed air.

It is apparent that when the plungers 4 and 5 compress air, the plungers 2 and 3 facing them, respectively, always suck air in sequence at different flow rates, although they compress each other by different amounts.

The operation described below can be continued indefinitely as required, with the movement of the plungers 2, 3, 4, 5 being regulated by the rotational speed of the motor 11 and shaft 12.

The operation of the positive displacement reciprocating compressor shown in figures 11-13 is substantially the same as that of the compressor 1 described above, with the difference that the longitudinal movement of the plungers 101, 102 is obtained by means of a known "crank-link assembly".

It is thus possible to ensure continuous production of compressed air and without downtime, which in use considerably reduces the interruptions of compressed air delivery, which are known to result in insufficient and undesirable operating conditions.

It is the axial movement generated by the driving means 10 and obtained by means of the plungers 2, 3, 4, 5 or 101, 102 that, in comparison with the known compressors, significantly reduces the wear of the sealing elements, designated by the reference numeral 28, interposed between the plungers 2, 3, 4, 5 or 101, 102 and the respective cylinders 6, 7, 8, 9.

The plunger 2, 3, 4, 5 or 101, 102 can therefore move up to the end of its stroke, which on the one hand prevents excessive wear of the sealing elements of the oscillating piston system compressor under the same conditions.

The aim of generating a greater air flow rate with the same constructive solution is thus achieved, this increase being obtained by increasing the efficiency of the compressor corresponding to the prior art.

Moreover, the lower wear of the sealing elements allows the frequency of maintenance, repair, or replacement stoppages to be reduced with respect to the prior art, with obvious advantages being obtained with respect to the costs involved.

It is important to note that with a simple structure and a compact size of the compressor, very practical use conditions can be obtained in some applications.

In addition, the compressor of the present invention provides the actual required compressed air flow rate in use and does not require the maintenance of the rated capacity in the compressed air storage tank for maintenance operation, as is required in the prior art.

The compressed air generated by each plunger 2, 3, 4, 5 is thus conveyed from the respective compression chamber to the collection chamber 32 and from the collection chamber to the location required for use.

The collection chamber 32 does not need to be of a large size and it can compensate for temporary anomalies in the operation of the compressor 1, in particular in the starting phase.

In addition, the air in the collection chamber is refillable within a few seconds, depending on the size of the compressor, so it is stable and allows the compressor to enter a ready-to-use state immediately after a subsequent start-up.

It is therefore evident that once the use of the positive-displacement compressor is over, a small amount of energy may be sufficient to maintain its ideal condition for subsequent use, and in any case lower than that required by the known compressors provided with a tank.

A number of other advantages of the present invention with respect to known compressors relate to the collection chamber 32.

First of all, the compressor of the invention ensures a steady and continuous flow of compressed air, even without the need to provide compressed air storage tanks, as is usual in corresponding known embodiments.

The structural complexity and overall dimensions of the volumetric compressor can therefore be further reduced, the reduction in overall dimensions allowing in any case better handling and transport.

Due to the reduced risk of explosion, consideration must be given to the safer conditions afforded by the omission of the canister.

It is evident that the manufacturer can vary the diameter of the plunger in order to set the generated compressed air flow rate according to the needs and operating conditions of the user.

However, the positive displacement compressor of the present invention provides a continuous and stable flow rate condition for any application.

It is also evident that the compressor of the invention can be provided with a seat and a handle for its transport and positioning in an upright position, which is not allowed for compressors provided with such a tank.

Therefore, based on the above description, it should be understood that the positive displacement reciprocating compressor of the present invention achieves all the advantages and objects described above.

Variations and modifications can be made to the positive displacement reciprocating compressor of the present invention which include, for example, a different number of plungers being moved by the driving means in order to obtain the desired air flow rate.

It is apparent that the diameter of the plunger may be changed simultaneously depending on the use conditions.

Otherwise, to achieve the desired flow, the manufacturer may increase the number of plungers indefinitely.

In addition, the arrangement of the compression chamber relative to the plunger may be different from that described above, for example it may be provided between the pistons and not below them.

All configurations not shown and described embodiments are within the scope of the appended claims.

Claims (22)

1. A reciprocating compressor (1; 200) of the positive-displacement type comprising at least one plunger (2, 3, 4, 5; 101, 102) slidably coupled inside a cylinder (6, 7, 8, 9), inside which a compression chamber (8a, 9a) is formed and which is operatively connected with a driving device (10; 201) for moving the plunger inside the cylinder (6, 7, 8, 9), the driving device (10; 201) comprising a motor (11) having a rotary shaft (12; 103) coupled with an eccentric (13; 100) mechanically connected to the plunger (2, 3, 4, 5; 101, 102) and able to force a longitudinal displacement of the plunger (2, 3, 4, 5; 101, 102) in a vertical direction with respect to an axis of rotation (Y) of the rotary shaft (12; 103), the eccentric (13; 100) comprising a rotary body extending substantially longitudinally, wherein on one side a tubular part (14) is coupled to the shaft (12; 103) and on the other side an eccentric pin (15; 104) is formed, characterized in that the eccentric pin (104) is provided with contrast means (105) for cooperation with a connecting rod (106) which is fastened to a lower bracket part (107) and an upper bracket part (108) which supports the plunger (101, 102).

2. A compressor (1; 200) as in claim 1, characterized in that the rotating body is provided on the outside with a shaped sleeve portion (21) coaxial with the tubular portion (14), the weight of the tubular portion (14) being balanced with respect to the eccentric pin (15; 104) during rotation of the rotating body.

3. A compressor according to claim 1, including a pair of mutually facing and coaxial plungers supported by the bracket member.

4. A compressor (200) as set forth in claim 1 wherein said head (106a) of said connecting rod (106) engages an opening (109) formed in said lower bracket member (107), said small end (106b) of said connecting rod (106) being coupled to said pin (110) by means of a needle bearing therebetween.

5. A compressor (1; 200) as in claim 4, characterized by the opening (109) being a through opening.

6. A compressor (200) as claimed in claim 1, characterized by comprising a pair of plungers (101, 102) facing each other and coaxial, supported by the lower bracket member (107) and the upper bracket member (108), parallel to and spaced apart from each other and coupled to the plungers (101, 102) at the outer peripheral edges (101a, 102a) of the plungers (101, 102).

7. A compressor (1; 200) as in claim 1, characterized in that the plunger (2, 3, 4, 5; 101, 102) is provided with a peripheral sealing element (28) projecting from a lateral edge (5a) of the plunger (2, 3, 4, 5; 101, 102) and held stable in position by a covering disc (29) mounted in a recess formed on the outer wall of the plunger (2, 3, 4, 5; 101, 102).

8. A compressor (1; 200) as in claim 7, characterized by the fact that the cover disc (29) is integrated with the plunger (2, 3, 4, 5; 101, 102) by means of first fastening means (30).

9. A compressor (1; 200) as in claim 1, characterized by comprising a shaped base (31; 202) supporting the plunger (2, 3, 4, 5; 101, 102).

10. A compressor (1; 200) as in claim 9, characterized by comprising a collecting chamber (32; 204) for the compressed air, provided with at least one inlet (33, 34) for the compressed air to communicate with the compression chamber (8a, 9a) of the cylinder (6, 7, 8, 9), and with at least one outlet for the compressed air to communicate with the outside.

11. A compressor (1) as in claim 10, characterized by the collection chamber (32) formed in the shaped base (31).

12. A compressor (200) as in claim 10, characterized in that the collecting chamber (204) comprises a tubular structure defining externally the driving means (201) and the shaped base (202).

13. A compressor (1) as in claim 10, characterized by the inlet (33, 34) being provided with a valve (35) which is open in the compression stroke and closed in the suction stroke.

14. A compressor (1) as in claim 11, characterized by the collecting chamber (32) having an annular configuration.

15. A compressor (1) as in claim 11, characterized by the shaped base (31) provided with a closing cover (36) of the collection chamber (32).

16. A compressor (1) as in claim 13, characterized by the valve (35) being an annular foil.

17. A compressor (1; 200) as in claim 9, characterized by comprising at least one head (37, 38, 39, 40) applied externally to the shaped base (31; 202) by means of fastening means (41) so as to be arranged to cover the cylinder (6, 7, 8, 9).

18. A compressor (1; 200) as in claim 17, characterized in that the head (37, 38, 39, 40) has at least one through hole (42, 43, 44) for sucking in said air to be compressed in the cylinder (6, 7, 8, 9).

19. A compressor (1; 200) as in claim 18, characterized by comprising a flexible thin vane (45) coupled with an inner wall (40a) of the head (37, 38, 39, 40), the inner wall (40a) being turned towards the cylinder (6, 7, 8, 9), and the flexible thin vane (45) being blocked at an end (45a, 45b) by having an outer peripheral edge (9b) of the cylinder (6, 7, 8, 9) close to the head (37, 38, 39, 40).

20. A compressor (1; 200) as in claim 19, characterized by the fact that the flexible thin blade (45) is arranged in the vicinity of the through hole (42, 43, 44) so as to be closed during the compression stroke and open during the suction stroke.

21. A compressor (200) as claimed in claim 9, characterized by comprising at least two wheels (205) connected to the shaped base (202) for steering.

22. A compressor (200) as claimed in claim 9, characterized by comprising handle means (203) connected to the shaped base (202) for the convenience of the user.