Pneumatic Actuators

Abstract

The first piston (114) of the first cylinder (110) and the second piston (134) of the second cylinder (130) are connected in a manner with the same displacement. The pressure area on one side of the first piston (114) is the smallest, and the pressure area on the same side of the second piston (134) is the third smallest. The two air chambers of the first cylinder (110) and the two air chambers of the second cylinder are called the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber in order from the smallest pressure area to the largest pressure area. At this time, the control valve (150) is connected to the air pressure source (102) on the first air chamber in the forward stroke, and the second air chamber and the third air chamber are connected, and the fourth air chamber is opened to the atmosphere (104).

Description

Technical Field

[0001] The present disclosure relates to pneumatic actuators. Background Art

[0002] Pneumatic actuators have advantages of being inexpensive and lightweight due to their simple structure compared to other actuators. In addition, pneumatic actuators can easily generate large forces. In addition, the air used in pneumatic systems is inexhaustible and clean. For these reasons, pneumatic systems using pneumatic actuators are used in assembly devices and transportation devices in various factories such as automobiles, semiconductors, and foods. In addition, unlike electric actuators, pneumatic actuators do not generate magnetic or electric fields, so they are suitable for applications that avoid magnetic or electric fields.

[0003] On the other hand, pneumatic actuators have the disadvantage of low energy efficiency because they need to release compressed air into the atmosphere in vain. Due to this disadvantage, there has been a trend in recent years to replace pneumatic actuators with electric actuators. Summary of the invention

[0004] Technical problem to be solved by the invention

[0005] The present disclosure is an invention in the above context, wherein one of the exemplary objects of the solution is to provide a pneumatic actuator with improved efficiency.

[0006] Technical means for solving technical problems

[0007] One scheme of the present disclosure relates to a cylinder. The cylinder includes a first cylinder, a second cylinder and a control valve. The first cylinder includes a first cylinder tube and a first piston that divides the space in the first cylinder tube into two air chambers. The second cylinder includes a second cylinder tube and a second piston, the second piston divides the space in the second cylinder tube into two air chambers, and is connected to the first piston in a manner with the same displacement amount, that is, in a manner of displacement energy linkage. Among the two pressure-bearing surfaces of the first piston and the two pressure-bearing surfaces of the second piston, one pressure-bearing area of ​​the first piston is the smallest, and the pressure-bearing area on the same side of the second piston is the third smallest. The two air chambers of the first cylinder and the two air chambers of the second cylinder are called the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber in the order of the pressure area from small to large. At this time, the control valve connects the air pressure source to the first air chamber, connects the second air chamber to the third air chamber, and opens the fourth air chamber to the atmosphere in the forward stroke.

[0008] One aspect of the present disclosure also relates to a cylinder. The cylinder includes a plurality of N (N≥2) cylinders and a control valve. Each of the N cylinders includes a cylinder tube and a piston that divides the space inside the cylinder tube into two air chambers. The pistons of each of the N cylinders are connected in a manner that the displacement amounts are equal, that is, in a manner that the displacement energy is linked. Among all the pressure surfaces of each piston of the N cylinders, the pressure area on one side of the i-th (1≤i≤N) piston is the (2i-1)th smallest. The two air chambers of each of the N cylinders are referred to as the first air chamber, the second air chamber, ..., the (2N-1)th air chamber, and the second (2N) air chamber in order from the smallest to the largest pressure area. At this time, the control valve (i) connects the air pressure source to the first air chamber in the forward stroke, opens the (2N) air chamber to the atmosphere, and connects the other two adjacent air chamber pairs.

[0009] Effects of the Invention

[0010] According to the solution of the present disclosure, the efficiency of the pneumatic actuator can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a diagram illustrating the energy required to compress air.

[0012] Figure 2 2(a) and 2(b) are diagrams illustrating the movement of the cylinder.

[0013] Figure 3 3(a) and 3(b) are diagrams for explaining a differential circuit in a hydraulic system.

[0014] Figure 4 4(a) and 4(b) are diagrams showing differential circuits in a pneumatic system.

[0015] Figure 5 It is a diagram showing a twin-cylinder actuator according to an embodiment.

[0016] Figure 6 This is a diagram for explaining the forward stroke of a double-acting double-cylinder actuator.

[0017] Figure 7 This is a diagram for explaining the return stroke of a double-acting double-cylinder actuator.

[0018] Figure 8 This is a diagram for explaining the return stroke of a single-acting double-cylinder actuator.

[0019] Fig. 9 This is a diagram for explaining the output characteristics of the forward stroke of the double-acting twin-cylinder actuator.

[0020] Fig.10 This is a diagram for explaining the output characteristics of a double-acting twin-cylinder actuator during the return stroke.

[0021] Fig.11This is a diagram for explaining the output characteristics of a single-acting twin-cylinder actuator during the forward stroke.

[0022] Fig.12 This is a diagram for explaining the output characteristics of a single-acting double-cylinder actuator during the return stroke.

[0023] Fig.13 This is a diagram showing the relationship between the output magnification of a double-acting double-cylinder actuator and α.

[0024] Fig.14 This is a graph showing the relationship between the output magnification of a single-acting double-cylinder actuator and α.

[0025] Fig.15 This is a diagram showing a twin-cylinder actuator whose output is smoothed.

[0026] Fig.16 (a)~ Fig.16 (c) is a diagram showing a basic form, a modified example 1, and a modified example 2 of a twin-cylinder actuator.

[0027] Fig.17 17 (a) and 17 (b) are diagrams showing Modification 3 and Modification 4 of the twin-cylinder actuator.

[0028] Fig.18 18 (a) and 18 (b) are diagrams showing twin-cylinder actuators of Modification 5 and Modification 6.

[0029] Fig.19 (a) of 19 and (b) of 19 are diagrams showing twin-cylinder actuators of Modification 7 and Modification 8.

[0030] Fig. 20 (a) and Fig. 20 (b) is a diagram showing a double-cylinder actuator using a single-rod cylinder.

[0031] Fig.21 It is a diagram showing a twin-cylinder actuator 100 a according to a ninth modification.

[0032] Fig. 22 It is a diagram showing a twin-cylinder actuator according to a tenth modification.

[0033] Fig.23 It is a diagram showing a twin-cylinder actuator according to Modification 11. DETAILED DESCRIPTION

[0034] (Overview of Embodiments)

[0035] The summary of several exemplary embodiments of the present disclosure is described. This summary is a prelude to the detailed description to be described later. For the purpose of basic understanding of the embodiments, some concepts of one or more embodiments are simplified and described, and the scope of the invention or disclosure is not limited. In addition, this summary is not a comprehensive overview of all possible embodiments and does not limit the indispensable components of the embodiments. For convenience, "one embodiment" is sometimes used to refer to one or more embodiments disclosed in this specification.

[0036] The cylinder of one embodiment includes a first cylinder, a second cylinder and a control valve. The first cylinder includes a first cylinder tube and a first piston that divides the space in the first cylinder body into two air chambers. The second cylinder includes a second cylinder body and a second piston that divides the space in the second cylinder tube into two air chambers, and the second piston is connected to the first piston in a manner with the same displacement. Of the two pressure-bearing surfaces of the first piston and the two pressure-bearing surfaces of the second piston, the pressure-bearing area on one side of the first piston is the smallest, and the pressure-bearing area on one side of the second piston is the third smallest. The two air chambers of the first cylinder and the two air chambers of the second cylinder are referred to as the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber in order of the pressure area from small to large. At this time, the control valve (i) connects the air pressure source to the first air chamber, connects the second air chamber and the third air chamber, and opens the fourth air chamber to the atmosphere in the forward stroke.

[0037] In this configuration, the second and third air chambers function as a differential circuit. Therefore, when compressed air remains in the second and third air chambers immediately before the forward stroke, the compressed air is expanded and used as the driving force of the piston, thereby effectively utilizing the energy of the compressed air to improve the efficiency of the cylinder. In addition, the combined force output by the two cylinders at this time is greater than that of a single cylinder.

[0038] In one embodiment, the control valve may also (ii) connect the first air chamber and the second air chamber to the air pressure source and connect the third air chamber and the fourth air chamber in the return stroke. In this form, the cylinder functions as a double-acting cylinder. In the return stroke, the pair of the first air chamber and the second air chamber and the pair of the third air chamber and the fourth air chamber function as a differential circuit, which can effectively utilize the energy in the residual compressed air while obtaining an output in the return direction. In addition, at this time, the combined force output by the two cylinders is greater than that of a single cylinder.

[0039] In one embodiment, the control valve may also (iii) connect the first air chamber and the second air chamber in a state of being disconnected from the air pressure source, and connect the third air chamber and the fourth air chamber in the return stroke. In this form, the cylinder functions as a single-acting cylinder and does not consume compressed air in the return stroke. In the return stroke, the first air chamber and the second air chamber as a pair and the third air chamber and the fourth air chamber as a pair function as a differential circuit, and can obtain an output in the return direction while effectively utilizing the energy in the remaining compressed air.

[0040] In one embodiment, the first cylinder and the second cylinder may also be arranged non-coaxially. In this case, the axial dimension of the cylinder can be reduced.

[0041] In one embodiment, the first air chamber and the second air chamber may be formed in the same cylinder, and the third air chamber and the fourth air chamber may be formed in the same cylinder.

[0042] In one embodiment, the first cylinder and the second cylinder may be single-rod cylinders, which may reduce costs.

[0043] In one embodiment, the first cylinder and the second cylinder may be coaxially arranged.

[0044] In one embodiment, the first air chamber, the second air chamber, the third air chamber and the fourth air chamber may be arranged sequentially in the axial direction.

[0045] In one embodiment, the third air chamber, the fourth air chamber, the first air chamber, and the second air chamber may be arranged sequentially in the axial direction.

[0046] In one embodiment, the first air chamber, the fourth air chamber, the third air chamber and the second air chamber may be arranged sequentially in the axial direction.

[0047] In one embodiment, the third air chamber, the second air chamber, the first air chamber and the fourth air chamber may be arranged sequentially in the axial direction.

[0048] In one embodiment, the control valve may include a four-way first control valve and a second control valve. The first control valve and the second control valve are configured as follows: (a) in the first position, the first port is connected to the second port, and the third port and the fourth port are in a closed state (closed), and (b) in the second position, the first port and the second port are in a closed state, and the fourth port is connected to the third port. Alternatively, the first port and the third port of the first control valve are connected to the second air chamber, the second port of the first control valve is connected to the third air chamber and the fourth port of the second control valve, the fourth port of the first control valve is connected to the first air chamber and the air pressure source, the first port and the third port of the second control valve are connected to the fourth air chamber, and the second port of the second control valve is connected to the atmosphere. In the case of a double-acting cylinder, the first control valve and the second control valve can be configured using commercially available products (four-way reversing valves or two two-way reversing valves), respectively.

[0049] (Implementation Method)

[0050] Hereinafter, the present disclosure will be described with reference to the accompanying drawings based on preferred embodiments. The same or equivalent constituent elements, components and processes shown in the accompanying drawings will be marked with the same reference numerals, and repeated descriptions will be appropriately omitted. In addition, the embodiments are not limited to the disclosure, but are examples, and all the features and combinations thereof described in the embodiments are not necessarily the essential contents of the disclosure.

[0051] In addition, for ease of understanding, the size (thickness, length, width, etc.) of each component described in the drawings is appropriately enlarged or reduced in some cases. In addition, the sizes of multiple components do not always represent the size relationship between them. Even if one component A is drawn thicker than another component B in the figure, component A may be thinner than component B.

[0052] 1. Efficiency of traditional pneumatic actuators

[0053] First, the efficiency of conventional pneumatic actuators was investigated.

[0054] The compressed air used in the pneumatic system is usually 0.7 MPa (gauge pressure) [= 0.8 MPa (absolute value)], which is produced by compressing air at atmospheric pressure (0.1 MPa (absolute value)) with a compressor.

[0055] Figure 1 is a diagram illustrating the energy required to compress air. The energy dE required to compress air of volume V at pressure P and reduce the volume by dV is represented by equation (1).

[0056] [Number 1]

[0057] dE=-PdV…(1)

[0058] On the other hand, the change in the state of air is expressed by equation (2), where T is temperature and R is the gas constant.

[0059] [Number 2]

[0060] PV=RT…(2)

[0061] The actual state change is not an isothermal change, but an adiabatic change or a polytropic change, but for the sake of ease of understanding or simplification of explanation, it is assumed to be an isothermal change. This assumption is useful for obtaining approximations because when considering the phenomenon on a longer time scale, the air temperature will eventually converge to the ambient temperature. If the state change is assumed to be an isothermal change, then dPV+pdV=dT=0, so equation (3) can be obtained from equation (1). Equation (4) is obtained by integrating equation (3).

[0062] [Number 3]

[0063]

[0064] [Number 4]

[0065]

[0066] Therefore, when the state change is assumed to be an isothermal change, the energy E0 required to compress air at atmospheric pressure Pa = 0.1 [MPa (abs)] into compressed air of pressure Ps = 0.8 [MPa (abs)] and volume V is expressed by equation (5).

[0067] [Number 5]

[0068]

[0069] Subsequently, the efficiency of pneumatic actuators will be explained using a cylinder as an example.

[0070] Figure 2 (a) and Figure 2 (b) is a diagram for explaining the operation of the cylinder 10. Figure 2 (a) indicates forward travel, Figure 2 (b) indicates a return stroke. The internal space of the cylinder 10 is divided into a left chamber 14 and a right chamber 16 by the piston 12 .

[0071] like Figure 2 As shown in (a), during the forward stroke, compressed air is supplied to the left chamber 14, and the right chamber 16 is opened to the atmosphere. Then, when the piston 12 reaches the right end, the supply of compressed air is stopped. At this time, the air pressure in the left chamber 14 is Ps.

[0072] Then, in Figure 2In the return stroke shown in (b), the left chamber 14 is opened to the atmosphere, and the compressed air with a pressure of Ps remaining in the left chamber 14 is discharged to the outside. Otherwise, the return stroke will not be able to proceed normally. In this case, the energy (work) E obtained by the air pressure in the forward stroke is expressed by equation (6). Where V is the volume of the left chamber 14.

[0073] [Number 6]

[0074] E=P s V…(6)

[0075] Therefore, if the normal usage method of discarding the compressed air in the return stroke is adopted, the energy efficiency η can be obtained from equations (5) and (6), as shown in equation (7).

[0076] [Number 7]

[0077]

[0078] That is, according to simple calculation, the efficiency is at most about 0.5. The reason for such low efficiency is that the high-pressure air in the left chamber 14 is directly discharged to the outside during the return stroke.

[0079] 2. Differential circuit

[0080] In the cylinder according to the embodiment described below, the energy efficiency is greatly improved by using the expansion process of high-pressure air to drive the cylinder without discarding the high-pressure air as it is. However, the pressure of air decreases as it expands, and it becomes unable to be used as a sufficient driving force. Therefore, in order to use the air in the expansion process for driving, some efforts are required.

[0081] 2.1 Differential circuit in hydraulic system

[0082] In understanding the cylinder according to the present embodiment, it is necessary to understand the differential circuit often used in the hydraulic circuit. Therefore, this section describes the differential circuit.

[0083] Figure 3 3 (a) and 3 (b) are diagrams showing a differential circuit 20 in a hydraulic system. The differential circuit 20 includes a hydraulic cylinder 30, a pump 22, a control valve 24, and an oil tank 26. The structure of the hydraulic cylinder 30 is similar to Figure 2 The same as the cylinder 10 , the internal space of the cylinder is divided into a left oil chamber 34 and a right oil chamber 36 by the piston 32 .

[0084] exist Figure 3 In the forward stroke (a), the oil from the pump 22 flows into the left oil chamber 34 of the cylinder, and the oil from the right oil chamber 36 returns to the oil tank 26.

[0085] On the other hand, Figure 3In the return stroke (b), the oil chambers 34 and 36 on both sides of the cylinder are pressurized at the same pressure. Here, the pressure receiving area A1 of the left oil chamber 34 of the piston 32 is different from the pressure receiving area A2 of the right oil chamber 36. In this example, the pressure receiving area A1 of the left oil chamber 34 is smaller than the pressure receiving area A2 of the right oil chamber 36 by the cross-sectional area AR of the piston rod 38.

[0086] That is, since the pressure receiving area of ​​the right oil chamber 36 is large, the leftward force becomes larger, and the piston rod 38 moves to the left. At this time, the oil from the left oil chamber 34 merges with the oil from the pump 22 and flows into the right oil chamber 36, so that the cylinder moves at a high speed. As described above, the characteristic of the differential circuit 20 is that the return stroke moves at a high speed, and the smaller the area difference |A2-A1| on both sides of the cylinder, the faster the movement. Assuming that the cylinder speed is v, the following equation is established.

[0087] [Number 8]

[0088] A 1 v+Q=A 2 v…(8)

[0089] Therefore, the cylinder speed v is expressed by equation (9). Since the oil from the pump 22 is used only to fill the volume of the piston rod 38, the thinner the rod, the faster the cylinder speed v.

[0090] [Number 9]

[0091]

[0092] On the other hand, the output is as shown in formula (10), the thinner the piston rod 38 (A R The smaller the value), the smaller the output.

[0093] [Number 10]

[0094] F=A 2 pA 1 p=(A 2 -A 1 )p=A N p…(10)

[0095] In order to utilize this characteristic, the differential circuit 20 has been used for a return stroke or the like when a high return speed is desired but a large output is not required.

[0096] 2.2 Application of differential circuit in pneumatic system

[0097] Subsequently, the application of the differential circuit in a pneumatic system will be described. Figure 4 4(a) and 4(b) are diagrams illustrating a differential circuit 40 in a pneumatic system. The differential circuit 40 includes a cylinder 10, a gas pressure source (compressor) 42, and a control valve 44.

[0098] Figure 4(a) represents a forward stroke, and its action is the same as that of the differential circuit 20 in the hydraulic system.

[0099] Figure 4 (b) shows the return stroke. The present inventors focused on a major feature in the return stroke that is not found in the hydraulic system when a differential circuit used in the hydraulic system is applied to the pneumatic system.

[0100] Specifically, when the differential circuit 40 is used in a pneumatic system, such as Figure 4 As shown in (b), the return stroke can be moved even without the supply of air from the air pressure source 42. This is because, unlike oil, air expands. Figure 4 In (b), since the passage connecting the left chamber 14 and the right chamber 16 of the cylinder is open, the pressures of the left chamber 14 and the right chamber 16 are the same, but there is an area difference (A 1 <A 2 ), thereby causing the piston 12 to move to the left (return stroke).

[0101] Let L be the length of the cylinder and x be the length of the right chamber 16 of the piston 12. The volume V of the air chamber in the cylinder is expressed by the following formula, and as the piston 12 moves to the left, that is, as the length x increases, the volume V increases continuously.

[0102] V=A 1 ×(L-x)+A 2 ×

[0103] =(A 2 -A 1 )×x+A 1 ×L

[0104] Assuming that the state change is an isothermal change, PV = constant, so when the volume V increases with the movement of the piston 12, the pressure P gradually decreases. It should be noted that if the air pressure source 42 is connected as shown by the dotted line in the figure, compressed air is supplied from the air pressure source 42, so even if the piston 12 moves, the pressure P will not decrease.

[0105] The above is the behavior of the differential circuit in a pneumatic system.

[0106] 3. Pneumatic actuator of the embodiment

[0107] The pneumatic actuator of the embodiment is described in detail below. The cylinder utilizes the concept of the differential circuit in three stages, and effectively utilizes all (or most) of the output of the compressed air "during the period of expansion from the supply pressure to the atmospheric pressure", thereby improving efficiency.

[0108] 3.1 Basic Configuration

[0109] The pneumatic actuator of this embodiment is used by directly connecting two cylinders with different pressure-bearing areas on both sides of the piston, and is hereinafter also referred to as a double-cylinder actuator. The double-cylinder actuator 100 has four pressure-bearing surfaces, and its pressure-bearing area is A on both sides of the first cylinder. 1 and A 2 and A on both sides of the second cylinder 3 and A 4 Their areas increase successively, making A 1 <A 2 <A 3 <A 4 .

[0110] Figure 5 1 is a diagram showing a twin-cylinder actuator 100 according to an embodiment. The twin-cylinder actuator 100 includes a first air cylinder 110, a second air cylinder 130, and a control valve 150. The control valve 150 may be a solenoid valve, but is not limited thereto. In the figure, the right side is the output direction in the forward stroke of the twin-cylinder actuator 100, and the left side is the output direction in the return stroke of the twin-cylinder actuator 100. In addition, it is assumed that the twin-cylinder actuator 100 repeatedly reciprocates a plurality of times.

[0111] The first cylinder 110 includes a first cylinder tube 112 and a first piston 114. The first piston 114 is displaceable in the first cylinder tube 112, and the space in the first cylinder tube 112 is partitioned into a left air chamber 116 and a right air chamber 118 by the first piston 114.

[0112] The pressure receiving area A of the first surface (left air chamber 116 side) of the first piston 114 1 Smaller than the pressure receiving area A of the second surface (right air chamber 118 side) 2 .

[0113] A 1 <A 2

[0114] In this embodiment, the first cylinder 110 is a double-rod cylinder, in which a left rod 120 is provided on the left air chamber 116 side of the first piston 114, and a right rod 122 is provided on the right air chamber 118 side. The cross-sectional area of ​​the first cylinder tube 112 is A C1 , the cross-sectional area of ​​the left rod 120 is A R1_L , the cross-sectional area of ​​the right rod 122 is A R1_R , at this time, the following relationship holds.

[0115] A 1 =A C1 -A R1＿L

[0116] A 2 =A C1 -A R1＿R

[0117] Among them, A R1＿L >A R1＿R

[0118] The second cylinder 130 includes a second cylinder tube 132 and a second piston 134. The second piston 134 is displaceable in the second cylinder tube 132, and the space in the second cylinder tube 132 is partitioned into a left air chamber 136 and a right air chamber 138 by the second piston 134.

[0119] The first cylinder 110 and the second cylinder 130 are arranged so that the first piston 114 and the second piston 134 are parallel to each other. In addition, the second piston 134 is connected to the first piston 114 so that the displacement is the same. Figure 5 In the embodiment, the second piston 134 and the first piston 114 are connected via the right rod 122 and the left rod 140 .

[0120] The pressure receiving area A of the first surface (left air chamber 136 side) of the second piston 134 3 Smaller than the pressure area A of the second side (right air chamber 138 side) 4 .

[0121] A 3 <A 4

[0122] In this embodiment, the second cylinder 130 is also a double-rod cylinder. A left rod 140 is provided on the left air chamber 136 side of the second piston 134, and a right rod 142 is provided on the right air chamber 138 side. The cross-sectional area of ​​the second cylinder tube 132 is A C2 , the cross-sectional area of ​​the left rod 140 is A R2_L , the cross-sectional area of ​​the right rod 142 is A R2_R , at this time, the following relationship holds.

[0123] A 3 =A C2 -A R2＿L

[0124] A 4 =A C2 -A R2＿R

[0125] Among them, A R2＿L >A R2＿R

[0126] In addition, in this embodiment, A 2 <A 3 The relationship holds. That is,

[0127] A 1 <A 2 <A 3 <A 4

[0128] The two air chambers 116 and 118 of the first cylinder 110 and the two air chambers 136 and 138 of the second cylinder 130 are respectively referred to as the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber in the order from the smallest to the largest pressure area, and the reference numerals 161, 162, 163, and 164 are newly added. In this example, they are related as follows.

[0129] First air chamber 161 = left air chamber 116 of first cylinder 110

[0130] The second air chamber 162 = the right air chamber 118 of the first cylinder 110

[0131] The third air chamber 163 = the left air chamber 136 of the second cylinder 130

[0132] Fourth air chamber 164 = right air chamber 138 of second cylinder 130

[0133] Part or all of the rods of the first cylinder 110 and the second cylinder 130 are used as design parameters of the pressure-bearing area, and they also serve as connecting means for connecting the first piston 114 and the second piston 134 .

[0134] In this example, the control valve 150 is shown as a 6-way two-position valve. The first port (1) to the sixth port (6) are respectively connected to the air pressure source 102, the atmosphere 104, and the first air chamber 161 to the fourth air chamber 164. In addition, the control valve 150 only needs to be able to switch between the first position and the second position described later, and the number of positions is not limited to two. For example, when it is assumed that the piston stops at a position in the middle of the stroke, a directional control valve with a closed center function can be used, in which case a three-position valve can be used. In addition, there is no particular restriction on the maintenance and operation method of the control valve, and a single solenoid type (spring return type), a double solenoid type, and various other types of valves can be used.

[0135] Generally speaking, there are two types of cylinders: a "double-acting cylinder" that outputs both in the forward stroke and the return stroke, and a "single-acting cylinder" that outputs only in the forward stroke but does not need to output in the return stroke but returns by a spring or its own weight. Therefore, the double-cylinder actuator 100 according to the embodiment may also have a double-acting cylinder and a single-acting cylinder. The structure of the control valve 150 differs depending on whether the double-cylinder actuator 100 is a single-acting cylinder or a double-acting cylinder. Therefore, hereinafter, the description will be made in the order of the double-acting cylinder and the single-acting cylinder.

[0136] (1) Double-acting cylinder

[0137] (1-1) Forward travel

[0138] Figure 61 is a diagram showing the forward stroke of the double-acting double-cylinder actuator 100a. In this forward stroke, the control valve 150a connects the first air chamber 161 and the air pressure source 102, connects the second air chamber 162 and the third air chamber 163, and opens the fourth air chamber 164 to the atmosphere 104. Specifically, the control valve 150a is set in the first position and conducts from the first port (1) to the third port (3), conducts between the fourth port (4) and the fifth port (5), and conducts from the sixth port (6) toward the second port (2).

[0139] In the forward stroke (movement of rightward output), compressed air is supplied to the first air chamber 161 to obtain rightward output. In addition, although the second air chamber 162 and the third air chamber 163 are connected, because A 2 <A 3 , so the rightward output can be obtained by the same principle as the differential circuit. The resultant force F of the two rightward outputs is greater than the output in the case of only one cylinder 110.

[0140] (1-2) Return trip

[0141] Figure 7 This is a diagram for explaining the return stroke of the double-acting twin-cylinder actuator 100a. In the return stroke, the control valve 150a connects the first air chamber 161 and the second air chamber 162 to the air pressure source 102, and connects the third air chamber 163 and the fourth air chamber 164. Specifically, the control valve 150a is set to the second position, the first port (1) and the third port (3) are connected to the fourth port (4), the fifth port (5) and the sixth port (6) are connected, and the second port (2) is closed (closed).

[0142] In the return stroke (movement output to the left), compressed air is supplied to the second air chamber 162. At the same time, since the second air chamber 162 and the first air chamber 161 of the first cylinder 110 are connected, and A 1 <A 2 , so the leftward output can be obtained by the same principle as the differential circuit.

[0143] In addition, although the third air chamber 163 and the fourth air chamber 164 of the second cylinder 130 are connected, due to A 3 <A 4 , so the leftward output can be obtained by the same principle as the differential circuit. The resultant force F of these two leftward outputs R This is greater than the output of the single cylinder 110 alone.

[0144] As mentioned above, in a double-acting cylinder, the output F during the forward stroke and the output F during the return stroke are R Both are greater than the output of the single cylinder 110. This is because the force generated during the expansion of the compressed air is also utilized.

[0145] For example, assuming that the pressure area ratio of the twin-cylinder actuator 100 is A 1 :A 2 :A 3 :A 4 =1:2:4:8, because the supply pressure of compressed air is usually 0.8 [MPa (abs)], so if the state change is an isothermal change, the pressure in each chamber is inversely proportional to the volume. Therefore, the pressure in each air chamber changes roughly as follows in each forward stroke and return stroke.

[0146] (Forward stroke)

[0147] First air chamber 161 = 0.8 MPa

[0148] Second air chamber 162 = 0.8 → 0.8 × (2 / 4) = 0.4 MPa

[0149] The third gas chamber 163 = 0.8 → 0.8 × (2 / 4) = 0.4 MPa

[0150] Fourth air chamber 164 = 0.1 MPa (atmospheric pressure)

[0151] (Return trip)

[0152] First air chamber 161 = 0.8 MPa

[0153] Second air chamber 162 = 0.8 MPa

[0154] The third gas chamber 163 = 0.4 → 0.4 × (4 / 8) = 0.2 MPa

[0155] Fourth air chamber 164 = 0.4 → 0.4 × (4 / 8) = 0.2 MPa

[0156] In the fourth air chamber 164, the pressure is reduced to about 0.2 MPa. It can be seen that the force of the expansion process of compressed air can be fully utilized to a pressure closer to atmospheric pressure than in conventional actuators. Furthermore, for example, if the output of the twin-cylinder actuator 100 is twice that of the single-cylinder 110, the entire pressure-receiving area of ​​the twin-cylinder actuator 100 can be reduced to half of the previous one in order to obtain the same output. As a result, the air consumption is halved, and the efficiency is close to 100% from the current about 50%.

[0157] When a single cylinder is used, noise is generated when compressed air is discharged to atmospheric pressure. In many cases, a muffler is inserted to reduce the sound. In the case of using the double cylinder actuator 100, since the air whose pressure is reduced to near atmospheric pressure is discharged, the muffler can be omitted, thereby reducing costs.

[0158] (2) Single-acting cylinder

[0159] (2-1) Forward travel

[0160] The forward stroke in a single-acting cylinder is the same as the forward stroke in a double-acting cylinder and is Figure 6 described, and therefore its description will be omitted.

[0161] (2-2) Return trip

[0162] Figure 8 1 is a diagram for explaining the return stroke of the single-acting double-cylinder actuator 100b. In the single-acting double-cylinder actuator 100b, the function of the control valve 150b in the return stroke is different from that of the double-acting control valve 150a. In the return stroke, the control valve 150b connects the first air chamber 161 and the second air chamber 162, and connects the third air chamber 163 and the fourth air chamber 164 in a state separated from the air pressure source 102. Specifically, the control valve 150b is set in the second position, the first port (1) and the second port (2) are closed, the third port (3) and the fourth port (4) are connected, and the fifth port (5) and the sixth port (6) are connected.

[0163] In the single-acting cylinder, since the output is not necessarily required in the return stroke (movement of output to the left), the compressed air from the air pressure source 102 is not supplied to the second air chamber 162. Therefore, the compressed air is not consumed during the return stroke. However, since the pair of the first air chamber 161 and the second air chamber 162 and the pair of the third air chamber 163 and the fourth air chamber 164 are respectively differential circuits, a certain degree of output can be obtained even in the return stroke.

[0164] Assume that the pressure area ratio of the dual-cylinder actuator 100 is A 1 :A 2 :A 3 :A 4 =1:2:4:8, the supply pressure of compressed air is 0.8 [MPa (abs)], at this time, the pressure in each air chamber changes approximately as follows in the forward stroke and the return stroke.

[0165] (Forward stroke)

[0166] First air chamber 161 = 0.8 MPa

[0167] Second air chamber 162 = 0.4 → 0.4 × (2 / 4) = 0.2 MPa

[0168] The third gas chamber 163 = 0.4 → 0.4 × (2 / 4) = 0.2 MPa

[0169] Fourth air chamber 164 = 0.1 MPa (atmospheric pressure)

[0170] (Return trip)

[0171] First air chamber 161 = 0.8 → 0.8 × (1 / 2) = 0.4 MPa

[0172] Second air chamber 162 = 0.8 → 0.8 × (1 / 2) = 0.4 MPa

[0173] The third gas chamber 163 = 0.2 → 0.2 × (4 / 8) = 0.1 MPa

[0174] The fourth gas chamber 164 = 0.2 → 0.2 × (4 / 8) = 0.1 MPa (atmospheric pressure)

[0175] In the final fourth air chamber 164, the pressure has dropped to 0.1 MPa, that is, atmospheric pressure. It can be seen that energy can be utilized more efficiently than a double-acting cylinder.

[0176] 4. Output characteristics of the twin-cylinder actuator 100

[0177] Next, the output characteristics of the twin-cylinder actuator 100 will be described separately for a double-acting cylinder and a single-acting cylinder.

[0178] (1) Double-acting cylinder

[0179] (1-1) Output during forward travel

[0180] Fig. 9 1 is a diagram showing the output characteristics of the double-acting double-cylinder actuator 100a in the forward stroke. Let L be the length of the first cylinder 110 and the second cylinder 130, and x be the position of the first piston 114 and the second piston 134. In the forward stroke, x = L is the initial state, and x = 0 is the final state. In the figure, t represents the thickness of the piston.

[0181] The pressures of the first air chamber 161, the second air chamber 162, the third air chamber 163, and the fourth air chamber 164 are respectively denoted as P 1 , P 2 , P 3 , P 4 .

[0182] exist Fig. 9 When the output in the right direction is F, because P 2 =P 3 , so equation (11) holds.

[0183] [Number 11]

[0184] F={A 1 P 1 -A 2 P 2 +(A 2 -A1 ) a}+{A 3 P 3 -A 4 P 4 +(A 4 -A 3 ) a}

[0185] =A 1 P 1 +(A 3 -A 2 ) 2 -A 4 P 4 +(A 2 +A 4 -A 1 -A 3 ) a …(11)

[0186] In the initial state of x = L, P 2 =P S , which is the final state following the previous return trip. As x→0, from P 2 =P 3 =P S Change to P 2 =P 3 =(A 2 / A 3 ) S In addition, due to P 1 =P S , P 4 =P a (Atmospheric pressure) maintains this state, so the output in the initial state is expressed by equation (12), and the output in the final state is expressed by equation (13).

[0187] [Number 12]

[0188]

[0189] [Number 13]

[0190]

[0191] (1-2) Output during return trip

[0192] Fig.10 1 is a diagram showing the output characteristics of the return stroke of the double-acting double-cylinder actuator 100a. In the return stroke, x=0 is the initial state, and x=L is the final state.

[0193] exist Fig.10 If the output on the left is F R, then P 1 =P 2 And P 3 =P 4 , so equation (14) holds.

[0194] [Number 14]

[0195] F R ={A 2 P 2 -A 1 P 1 -(A 2 -A 1 ) a}+{A 4 P 4 -A 3 P 3 -(A 4 -A 3 ) a}

[0196] =(A 2 -A 1 ) 1 +(A 4 -A 3 ) 3 -(A 2 +A 4 -A 1 -A 3 ) a …(14)

[0197] In this case, the pair of the first air chamber 161 and the second air chamber 162 and the pair of the third air chamber 163 and the fourth air chamber 164 are connected to each other, and compressed air from the air pressure source 102 as a pressure source is supplied to the second air chamber 162. In the initial state x=0, P 3 =(A 2 / A 3 ) S , which is the final state of the previous forward journey. As x→L, from P 3 =(A 2 / A 3 ) S Change to P 3 =P 4 =(A 2 / A 3 ) s ×(A 3 / A 4 )=(A 2 / A 4 ) s The first air chamber 161 and the second air chamber 162 are P1 =P 2 =P S remains unchanged. Therefore, the output of the initial state is expressed by equation (15), and the output of the final state is expressed by equation (16).

[0198] [Number 15]

[0199]

[0200] [Number 16]

[0201]

[0202] Here, as an example, regarding A 2 / A 1 =A 3 / A 2 =A 4 / A 3 = 2, try to find F and F of the double-acting cylinder R This is A 4 =2A 3 =4A 2 =8A 1 In addition, the supply pressure of compressed air is P S =0.8MPa(abs). That is, P S =8P a .

[0203] The output F in the initial state and the final state during the forward stroke are as follows.

[0204] [Number 17]

[0205]

[0206] In addition, the output F of the initial state and the final state during the return trip R The following values ​​are given.

[0207] [Number 18]

[0208]

[0209] In both cases, the output of the dual-cylinder actuator at the start of the movement is much greater than the output of the single-cylinder 110 1 P S However, at the end of the movement, it becomes less than 2 times. In many cases, this is not a problem, because the initial movement of the cylinder is important. More precisely, the outputs F, F in the final state R The smaller case can be viewed as a pseudo cushion at the end of the stroke, which may be desirable in some applications.

[0210] In addition, if the output reduction of the final state becomes a problem, it is necessary to smooth the outputs of the initial state and the final state. This method will be described later.

[0211] (2) Single-acting cylinder

[0212] The output of the single-acting double-cylinder actuator 100b is described here. A single-acting cylinder is a cylinder that outputs during the forward stroke, but does not need to output during the return stroke and returns by a spring or its own weight.

[0213] (2-1) Output during forward travel

[0214] Fig.11 1 is a diagram showing the output characteristics of the single-acting twin-cylinder actuator 100b in the forward stroke. In the forward stroke, x=L is the initial state, and x=0 is the final state.

[0215] exist Fig.11 In the example, assuming that the output pointing to the right is F, since P2=P3, the following equation holds.

[0216] [Number 19]

[0217] F={A 1 P 1 -A 2 P 2 +(A 2 -A 1 ) a}+{A 3 P 3 -A 4 P 4 +(A 4 -A 3 ) a}

[0218] =A 1 P 1 +(A 3 -A 2 ) 2 -A 4 P 4 +(A 2 +A 4 -A 1 -A 3 ) a …(11)

[0219] In this case, in the initial state x = L, P 2 =(A 1 / A 2 ) S , which is the final state of the return trip immediately preceding it, but as x→0 changes, from P2 =P 3 =(A 1 / A 2 ) S Change to P 2 =P 3 =(A 1 / A 2 ) S ×(A 2 / A 3 )=(A 1 / A 3 ) S In addition, P 1 =P S , P 4 =P a (Atmospheric pressure) remains unchanged, so the output F in the initial state is expressed by equation (17), and the output F in the final state is expressed by equation (18).

[0220] [Number 20]

[0221] When x = L,

[0222]

[0223] [Number 21]

[0224] At x=0,

[0225]

[0226] (2-2) Output during the return trip

[0227] Fig.12 1 is a diagram showing the output characteristics of the single-acting twin-cylinder actuator 100b in the return stroke. In the return stroke, x=0 is the initial state, and x=L is the final state.

[0228] exist Fig.12 When the left output is F R When P 1 =P 2 And P 3 =P 4 , so equation (14) holds.

[0229] [Number 22]

[0230] F R ={A 2 P 2 -A 1 P 1 -(A 2 -A 1 ) a}+{A4 P 4 -A 3 P 3 -(A 4 -A 3 ) a}

[0231] =(A 2 -A 1 ) 1 +(A 4 -A 3 ) 3 -(A 2 +A 4 -A 1 -A 3 ) a …(14)

[0232] In this case, the first air chamber 161 and the second air chamber 162 are connected as well as the third air chamber 163 and the fourth air chamber 164 are connected as well. 3 =P 4 =(A 1 / A 3 ) S , which is the final state following the previous trip, and P 1 =P 2 =P S As x→L changes, from P 1 =P 2 =P S Change to P 1 =P 2 =(A 1 / A 2 ) S , from P 3 =P 4 =(A 1 / A 3 ) s Change to P 3 =P 4 =(A 1 / A 3 ) s ×(A 3 / A 4 )=(A 1 / A 4 ) S Therefore, the output F of the initial state in the return trip R As shown in formula (19), the final state output F R It is expressed by formula (20).

[0233] [Number 23]

[0234]

[0235] [Number 24]

[0236]

[0237] Here, as an example, in A 2 / A 1 =A 3 / A 2 =A 4 / A 3 =2, try to find F and F of the single-acting cylinder R This is A 4 =2A 3 =4A 2 =8A 1 The supply pressure of compressed air is P S =0.8MPa(abs). That is, P S =8P a .

[0238] The output F in the initial state and final state during the forward stroke is as follows.

[0239] [Number 25]

[0240]

[0241] [Number 26]

[0242]

[0243] In a single-acting cylinder, only the output F of the forward stroke is important. The output in the initial state of the forward stroke is larger than that of a single cylinder, but it is not about twice as large, and in the final state, it is not much different from that of a single cylinder. This is because no compressed air is supplied in the return stroke.

[0244] 5. Optimization of cylinder pressure area

[0245] (1) Description of design parameters

[0246] Here, the pressure receiving area ratio of the cylinder is studied. First, the pressure receiving area ratio is set as follows.

[0247] A 2 / A 1 =α

[0248] A 3 / A 2 =β

[0249] A 4 / A 3 =γ

[0250] In this state, there are three parameters, so it is difficult to study. Therefore, here, we will study with α=γ as the constraint condition. This is because α and γ are the area ratios on both sides of the same cylinder. Therefore, it becomes as follows.

[0251] A 2 / A 1 =α

[0252] A 3 / A 2 =β

[0253] A 4 / A 3 =α

[0254] In addition, the supply pressure of compressed air is P S =0.8MPa(abs), that is, P S =8P a Therefore, in order to utilize all the forces generated when compressed air expands to atmospheric pressure, the product of the area ratios is set to 8. That is,

[0255] Set α 2 β=8

[0256] This limitation.

[0257] (2) Relationship between the output and pressure area ratio of a double-acting cylinder

[0258] Substituting the above design parameters into equations (12) and (13), the output F during the forward stroke is obtained, which is expressed as follows.

[0259] [Number 27]

[0260]

[0261] Substituting the above design parameters into equations (15) and (16), the output FR during the return stroke is calculated as shown below.

[0262] [Number 28]

[0263]

[0264] Fig.13 This is a graph showing the relationship between the output magnification and α of the double-acting double-cylinder actuator 100. During the forward stroke (x = L → 0), the output F changes from the line of the output F (x = L) to the line of the output F (x = 0). During the return stroke (x = 0 → L), the output F R From the output F R Line output F of (x=0) R (x=L) line transformation.

[0265] The average of the outputs of both during this period becomes larger than 2 in the vicinity indicated by the thick arrow in the figure.

[0266] When α = 2.06 and β = 1.89, F(average) = (2.04)A 1 P S , F R (Average) = (2.04) A 1 P S .

[0267] In this case, the average value of the output F during the forward stroke and the output F during the return stroke R The average value is about the output A of a single cylinder 1 P S twice as much.

[0268] (3) Relationship between output and pressure area ratio of single-acting cylinder

[0269] Substituting the above design parameters into equations (17) and (18), the output F during the forward stroke is obtained, which is expressed as follows.

[0270] [Number 29]

[0271]

[0272] Substituting the above design parameters into equations (19) and (20), the output FR during the return stroke is obtained, which is expressed as follows.

[0273] [Number 30]

[0274]

[0275] Fig.14 This is a graph showing the relationship between the output magnification and α of the single-acting double-cylinder actuator 100. During the forward stroke (x = L → 0), the output F changes from the line of the output F (x = L) to the line of the output F (x = 0). During the return stroke (x = 0 → L), the output F R From the output F R Line output F of (x=0) R (x=L) line transformation.

[0276] The average output during the forward stroke is greater than 2, and near the thick arrow in the figure, the output in the second half of the action is also relatively large.

[0277] When α = 1.51 and β = 3.51, F(average) = (2.0)A 1 P S , F R (maximum value) = (0.45) A 1 P S .

[0278] In this case, the average value F(average) of the output F during the forward stroke is the output A of a single cylinder. 1 P S On the other hand, although the output during the return stroke is not required, an output close to half of the single-cylinder output can be obtained.

[0279] 6. Smoothing of the output of the twin-cylinder actuator 100

[0280] As described above, in the twin-cylinder actuator 100, when the displacement of the cylinder increases, the pressure in the cylinder decreases, and the output decreases. In applications where such changes are not desired, a "negative spring characteristic" can be introduced to smooth the output.

[0281] Fig.15 1 is a diagram showing a dual-cylinder actuator 100A after smoothing the output. The dual-cylinder actuator 100A includes magnets 170 and 172 disposed near the end of the stroke, i.e., near x=L and x=0. The magnets 170 and 172 provide a characteristic similar to a negative spring characteristic. Specifically, as the pistons 114 and 134 approach the end of the stroke, the output decreases, but the attractive force of the magnets 170 and 172 compensates for the decrease. At the beginning of the stroke, the outputs F and F of the cylinders are R This can smooth the outputs F and F in the initial and final states to a certain extent. R .

[0282] Furthermore, the method of introducing the negative spring characteristic is not limited to the method using a magnet, and for example, a method such as attaching a two-position stabilizing spring to the piston may be considered.

[0283] Furthermore, in the case of a single-acting cylinder, magnet 170 is not required and only magnet 172 may be used.

[0284] As described above, the present disclosure has been described based on the embodiments. The embodiments are examples, and various modifications can be made to the combination of each component and each processing process. In addition, those skilled in the art will understand that such modifications are also within the scope of the present disclosure. In the following, such modifications will be described.

[0285] Fig.16 (a)~ Fig.16 (c) is a diagram showing a basic form of the twin-cylinder actuator 100 and Modifications 1 and 2 of the twin-cylinder actuator 100 .

[0286] Fig.16 (a) is the basic form of the double cylinder actuator 100, which has Figure 5 The same configuration as in A 1 <A2 <A 3 <A 4 In addition, Fig.16 In (a), the right rod 122 of the first cylinder 110 and the left rod 140 of the second cylinder 130 have the same cross-sectional area.

[0287] In the basic form, the first cylinder 110 and the second cylinder 130 are double-rod cylinders, but are not limited thereto. Fig.16 In the first modification of (b), the single-rod cylinder of the right rod 142 is omitted for the second cylinder 130. Also in this case, keep A 1 <A 2 <A 3 <A 4 relationship.

[0288] exist Fig.16 In the second modification example (c), the arrangements of the first cylinder 110 and the second cylinder 130 are interchanged.

[0289] Fig.17 17 (a) and 17 (b) are views showing Modification 3 and Modification 4 of the twin-cylinder actuator 100. Fig.17 In the modification 3 of (a), Fig.16 The positions of the second air chamber 162 and the fourth air chamber 164 in (a) are interchanged. That is, the left air chamber 116 of the first cylinder 110 is assigned to the first air chamber 161, the right air chamber 118 of the first cylinder 110 is assigned to the fourth air chamber 164, the left air chamber 136 of the second cylinder 130 is assigned to the third air chamber 163, and the right air chamber 138 of the second cylinder 130 is assigned to the second air chamber 162. Here, A 1 <A 2 <A 3 <A 4 The relationship also holds.

[0290] exist Fig.17 In the modification 4 of (b), Fig.17 (a) The first cylinder 110 and the second cylinder 130 are interchanged. Fig.16 (c) of FIG. 17 and (a) of FIG. 17 and (b) of FIG. 17 show a control valve 150a for a double-acting cylinder, but it can also be replaced by a control valve 150b for a single-acting cylinder.

[0291] from Fig.16 (a) to Fig.16 (c) and Fig.17 (a) and Fig.17The following techniques can be mastered in (b). The dual-cylinder actuator 100 includes a first cylinder 110 and a second cylinder 130, wherein the first piston 114 and the second piston 134 are connected to have the same displacement. The first piston 114 has two pressure-bearing surfaces, and the second piston 134 has two pressure-bearing surfaces, for a total of four pressure-bearing surfaces, among which the pressure-bearing area (A) of one side of the first piston 114 (the left side in the figure) is the smallest. 1 ), the pressure area on the same side (left side) of the second piston 134 is the third smallest (A 3 ). The two air chambers of the first cylinder 110 and the two air chambers of the second cylinder are called the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber in order from the air chamber with the smallest pressure area. At this time, (i) in the forward stroke, the control valve 150 connects the air pressure source to the first air chamber, connects the second air chamber and the third air chamber, and opens the fourth air chamber to the atmosphere.

[0292] Fig.18 (a) and Fig.18 (b) is a diagram showing a twin-cylinder actuator 100a according to Modification 5 and Modification 6. In the embodiments so far, the first cylinder 110 and the second cylinder 130 are coaxially arranged, but the present invention is not limited thereto.

[0293] exist Fig.18 In the modification 5 of (a), Figure 1 The first cylinder 110 and the second cylinder 130 of the dual cylinder actuator 100 are arranged in a non-coaxial manner (in parallel). For example, the first piston 114 and the second piston 134 are connected to each other at the right rod 122, 142 through a connecting member 180. The connecting member 180 can be the load 2 itself.

[0294] Fig.18 The modification 6 shown in (b) omits Fig.18 The right rod 122 and the right rod 142 of the modification 5 of (a). The first piston 114 and the second piston 134 are connected to the left rods 120 and 140 via a connecting member 180. The connecting member 180 may be the load 2 itself.

[0295] Fig.19 (a) and Fig.19 (b) is a diagram showing a twin-cylinder actuator 100 according to Modification 7 and Modification 8. Fig.19 In the modification 7 of (a), Fig.16 In the modification example 3 of (c), the first cylinder 110 and the second cylinder 130 are arranged in a non-coaxial manner (in parallel). The first piston 114 and the second piston 134 are connected to the right rods 122 and 142 through a connecting member 180. The connecting member 180 may be the load 2 itself.

[0296] exist Fig.19 In the modification example 8 of (b), the Fig.19 In the modification 7 of (a), the first piston 114 and the second piston 134 are connected to the left rods 120 and 140 via the connection member 180. In the modification 8, the right rod 122 is omitted.

[0297] exist Fig.18 In (a), (b) of 18, (a) of 19 and (b) of 19, a control valve 150a for a double-acting cylinder is shown, but it can be replaced by a control valve 150b for a single-acting cylinder.

[0298] Generally speaking, single-rod cylinders are cheaper than double-rod cylinders. Fig. 20 20(a) and 20(b) are views showing a double-cylinder actuator 100a using a single-rod cylinder. Fig. 20 (a) will Fig.18 The twin-cylinder actuator 100a of (b) is reversed left and right and applies force to the load on the right side of the paper. The twin-cylinder actuator 100a pulls the load in the forward stroke and pushes the load in the return stroke. Fig. 20 In (b), Fig. 20 (a) is the opposite, changing the method of extracting force so that the load is pushed in the forward stroke and pulled in the return stroke. Although the control valve 150a for the double-acting cylinder is Fig. 20 20(a) and 20(b) are shown, but can be replaced by a control valve 150b for a single-acting cylinder.

[0299] Fig.21 1 is a diagram showing a twin-cylinder actuator 100a according to a ninth modification. The twin-cylinder actuator 100a is a double-acting actuator. Fig. 20 The structure of the control valve 150a is changed based on the twin-cylinder actuator 100a of (b). Fig.21 In the embodiment, the control valve 150a includes a first control valve 152 and a second control valve 154. The first control valve 152 and the second control valve 154 are respectively four-way two-position valves (four-way two-position directional control valves). In the first state (first position), the control valves 152 and 154 are connected from the first port (1) to the second port (2), and the third port (3) and the fourth port (4) are closed. In the second state (second position), the first port (1) and the second port (2) of the control valves 152 and 154 are closed, and the fourth port (4) is connected to the third port (3).

[0300] The first port (1) and the third port (3) of the first control valve 152 are connected to the second air chamber 162. The second port (2) of the first control valve 152 is connected to the third air chamber 163 and the fourth port (4) of the second control valve 154. The fourth port (4) of the first control valve 152 is connected to the first air chamber 161 and the air pressure source 102. The first port (1) and the third port (3) of the second control valve 154 are connected to the fourth air chamber 164. The second port (2) of the second control valve 154 is connected to the atmosphere 104.

[0301] exist Fig.21 In the embodiment, the first control valve 152 and the second control valve 154 are in the first position, thereby realizing the forward stroke. By switching the first control valve 152 and the second control valve 154 to the second position, the return stroke can be realized. The 4-way 2-position directional control valve or the 4-way 3-position directional control valve with the closed-center function added thereto is a universal component, so Fig.21 The twin-cylinder actuator 100a can be realized at low cost by using commercially available products.

[0302] Fig. 22 10 is a diagram showing a twin-cylinder actuator 100a according to a modification 10. Fig.21 The first control valve 152 is divided into two two-way two-position directional control valves 152_1 and 152_2. Fig.21 The second control valve 154 is divided into two two-way two-position directional control valves 154_1 and 154_2. Since the two-way two-position reversing valve is a general component, it can be realized at a low cost by using a commercially available product.

[0303] Fig.23 11. The twin-cylinder actuator 100b is a diagram showing a twin-cylinder actuator 100b according to a modification 11. Fig.21 The control valve 150b includes a first control valve 155 and a second control valve 154. The structure of the second control valve 154 is similar to Fig.21 The first control valve 155 is a four-way two-position directional control valve, wherein the first port (1) is connected to the second air chamber 162, the second port (2) is connected to the third air chamber 163, the third disconnect port (3) is connected to the first air chamber 161, and the fourth port (4) is connected to the air pressure source 102.

[0304] In the first state (first position), the first control valve 155 is connected from the first port (1) to the second port (2) and from the fourth port (4) to the third port (3). In the second state (second position), the third port (3) of the first control valve 155 is connected to the first port (1) (open state), and the second port (2) and the fourth port (4) are closed.

[0305] exist Fig.23 In the embodiment, the first control valve 155 and the second control valve 154 are in the first position, thereby realizing the forward stroke. When the first control valve 155 and the second control valve 154 are switched to the second position, the return stroke can be realized. The second control valve 154 can use a general product.

[0306] Similar to Fig. 22 A variation of Fig.23 The four-way directional control valve can also be divided into two-way directional control valves.

[0307] In addition to the modifications shown here, there are various modifications of the configuration of the control valves 150 a and 150 b , and these modifications are also included in the scope of the present disclosure.

[0308] (Other Modifications)

[0309] In this embodiment, the dual-cylinder actuator 100 is composed of two cylinders with rods, but the present invention is not limited thereto.

[0310] For example, the twin-cylinder actuator 100 may be constructed by combining two cylinders with guides.

[0311] Alternatively, the twin cylinder actuator 100 may be constructed by combining two rodless cylinders. There are two types of rodless cylinders: a slit type and a magnet type. When the slit type is used, the pressure receiving area may be changed like a rod by extending a buffer tube extending from the center of the cylinder head to the piston according to the cross-sectional area of ​​the buffer tube. Even in the case of the magnet type, the pressure receiving area may be adjusted according to the cross-sectional area of ​​the rod by adding a rod inside.

[0312] As described above, the structure of the cylinders constituting the twin-cylinder actuator 100 is not particularly limited, and the actuator may be constructed by combining various cylinders having different pressure receiving areas of the pistons in the two air chambers.

[0313] In the embodiment, the dual-cylinder actuator 100 including two cylinders has been described, but the number of cylinders may be increased to three, four, ..., which will be generalized and referred to as a multi-cylinder actuator. The multi-cylinder actuator has the following features.

[0314] The multi-cylinder actuator includes a plurality of N (N≥2) cylinders and a control valve. Each of the N cylinders includes a cylinder tube and a piston that divides the space in the cylinder tube into two air chambers. The pistons of each of the N cylinders are connected so that the displacement is equal. The pressure area on one side of the i-th (1≤i≤N) piston is the (2i-1)th smallest. The two air chambers of each of the N cylinders (a total of 2N air chambers) are called the first air chamber, the second air chamber, ..., the (2N-1)th air chamber and the (2N)th air chamber in order from the smallest to the largest pressure area. At this time, (i) in the forward stroke, the control valve connects the air pressure source to the first air chamber, opens the (2N) air chamber to the atmosphere, and connects the other two adjacent air chamber pairs.

[0315] In the double-acting multi-cylinder actuator, (ii) in the return stroke, the control valve connects the first air chamber and the second air chamber to the air pressure source. In addition, from the third air chamber to the (2N)th air chamber, two adjacent air chamber pairs are connected.

[0316] In the single-acting multi-cylinder actuator, (iii) in the return stroke, the control valve connects two adjacent air chamber pairs from the first air chamber to the (2N)th air chamber.

[0317] Although the present disclosure has been described using specific terms based on the embodiments, the embodiments merely indicate the principles and applications of the present disclosure, in which many variations and arrangement changes are allowed without departing from the idea of ​​the present invention defined in the scope of protection.

[0318] Industrial Applicability

[0319] The present disclosure may be used in pneumatic actuators.

[0320] Description of Reference Numerals

[0321] 10 Cylinders

[0322] 12 Piston

[0323] 14 Left air chamber

[0324] 16 Right air chamber

[0325] 34 Left oil chamber

[0326] 36 Right oil chamber

[0327] 100 Double Cylinder Actuator

[0328] 102 Air pressure source

[0329] 104 Atmosphere

[0330] 110 First Cylinder

[0331] 112 First cylinder pipe

[0332] 114 First Piston

[0333] 116 Left air chamber

[0334] 118 Right air chamber

[0335] 120 Left lever

[0336] 122 Right lever

[0337] 130 Second Cylinder

[0338] 132 Second cylinder pipe

[0339] 134 Second Piston

[0340] 136 Left air chamber

[0341] 138 Right Air Chamber

[0342] 140 Left lever

[0343] 142 Right Rod

[0344] 150 Control valve

[0345] 152 First control valve

[0346] 154 Second control valve

[0347] 161 First Air Chamber

[0348] 162 Second Air Chamber

[0349] 163 Third Air Chamber

[0350] 164 Fourth Air Chamber

Claims

1. A pneumatic actuator, characterized in that: have: A first cylinder, comprising a first cylinder tube and a first piston, wherein the first piston divides the space in the first cylinder tube into two air chambers; A second cylinder, comprising a second cylinder tube and a second piston, the second piston dividing the space in the second cylinder tube into two air chambers and connected to the first piston in a manner with the same displacement amount; as well as Control valves, Among the two pressure-bearing surfaces of the first piston and the two pressure-bearing surfaces of the second piston, the pressure-bearing area on one side of the first piston is the smallest, and the pressure-bearing area on the same side of the second piston is the third smallest. The two air chambers of the first cylinder and the two air chambers of the second cylinder are called the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber in order from the smallest pressure area to the largest. At this time, the control valve can be operated to position the pneumatic actuator in the forward stroke so that the air pressure source is only connected to the first air chamber, the second air chamber is only connected to the third air chamber, and only the fourth air chamber is open to the atmosphere.

2. The pneumatic actuator according to claim 1, characterized in that: The control valve is operable to position the pneumatic actuator in a return stroke so that the air pressure source is connected only to the first air chamber and the second air chamber, and the third air chamber is connected only to the fourth air chamber.

3. The pneumatic actuator according to claim 1, characterized in that: The control valve is operable to position the pneumatic actuator in a return stroke so that the first air chamber is connected only to the second air chamber in a state separated from the air pressure source, and the third air chamber is connected only to the fourth air chamber.

4. The pneumatic actuator according to claim 1, characterized in that: The first cylinder and the second cylinder are arranged non-coaxially.

5. The pneumatic actuator according to claim 4, characterized in that: The first air chamber and the second air chamber are formed in the same cylinder, and the third air chamber and the fourth air chamber are formed in the same cylinder.

6. The pneumatic actuator according to claim 5, characterized in that: The first cylinder and the second cylinder are single-rod cylinders.

7. The pneumatic actuator according to claim 1, characterized in that: The first cylinder and the second cylinder are coaxially arranged.

8. The pneumatic actuator according to any one of claims 1 to 7, characterized in that: The control valve comprises a first control valve and a second control valve with four ports. The first control valve and the second control valve are configured such that: (a) in a first position, the first port is connected to the second port, and the third port and the fourth port are closed; (b) in a second position, the first port and the second port are closed, and the fourth port is connected to the third port. The first port and the third port of the first control valve are connected to the second air chamber, the second port of the first control valve is connected to the third air chamber and the fourth port of the second control valve, the fourth port of the first control valve is connected to the first air chamber and the air pressure source, the first port and the third port of the second control valve are connected to the fourth air chamber, and the second port of the second control valve is connected to the atmosphere.

9. A pneumatic actuator, characterized in that: have: N cylinders, wherein N ≥ 2, each of the N cylinders comprises a cylinder tube and a piston, and the piston divides the space in the cylinder tube into two air chambers; and Control valves, The pistons of the N cylinders are connected in such a way that the displacements are equal. Among all the pressure-bearing surfaces of the pistons of the N cylinders, the pressure-bearing area on one side of the i-th piston is the (2i-1)th smallest, where 1≤i≤N, When the two air chambers of each of the N cylinders are called the first air chamber, the second air chamber, ..., the (2N-1)th air chamber, and the (2N)th air chamber in order from the smallest pressure area to the largest, the control valve can be operated to position the pneumatic actuator in the forward stroke so that the air pressure source is only connected to the first air chamber, only the (2N)th air chamber is connected to the atmosphere, the second air chamber is only connected to the third air chamber, the fourth air chamber is only connected to the fifth air chamber, ..., and the (2N-2)th air chamber is only connected to the (2N-1)th air chamber.

Images