Variable flow semi-closed circuit scuba and method of breathing

Abstract

This invention discloses a variable flow semi-closed recirculating breathing apparatus and its breathing method. The breathing circuit comprises a human breathing system, an exhalation bag, an absorbent canister, an inhalation bag, and the human breathing system connected in sequence. It includes an oxygen partial pressure sensor connected to the exhalation bag, a constant flow valve and an electronic control valve connected in parallel between the inhalation bag and a nitrogen-oxygen mixture cylinder, and a control unit connected between the oxygen partial pressure sensor and the electronic control valve. The control unit has a pre-stored oxygen concentration setpoint = target maximum oxygen partial pressure / (0.1 * maximum working depth + 1), and the oxygen concentration of the nitrogen-oxygen mixture is higher than the setpoint. The constant flow valve is always open to supply air at the minimum flow rate corresponding to the maximum working depth. The oxygen partial pressure sensor detects the oxygen partial pressure in the breathing circuit in real time. The control unit calculates the oxygen concentration based on the oxygen partial pressure. When the oxygen concentration is lower than the setpoint, the electronic control valve opens, and the breathing circuit replenishes the nitrogen-oxygen mixture until the oxygen concentration increases to the setpoint, at which point the electronic control valve closes.

Description

Technical Field

[0001] This invention relates to the field of diving breathing apparatus technology, and in particular to a variable flow semi-closed circulation diving breathing apparatus and its breathing method. Background Technology

[0002] Diving respirators are essential equipment for ensuring the safety of divers' underwater breathing. Based on the different air supply methods, diving respirators can be divided into open-circuit respirators and circulating respirators. Open-circuit respirators directly release the diver's exhaled air into the water, which cannot be recycled, resulting in shorter underwater working time and poor concealment; they are mainly used for recreational diving. Circulating respirators retain most or all of the diver's exhaled air within the system, purifying it before reuse, greatly improving gas utilization. This not only extends underwater working time but also enhances underwater concealment, making them primarily used for military diving and scientific diving such as underwater photography and specimen collection. Due to the specific applications and obvious advantages of circulating respirators, various countries have attached great importance to their research and development. However, their complex structure and high requirements for maintenance and operation skills make their development crucial. Therefore, in-depth analysis of the types and characteristics of circulating respirators, and the rational selection, development, and safe use of circulating respirators according to specific diving applications, have significant military and social implications. Among them, the semi-closed diving respirator is a type of circulating respirator, typically employing a constant mass flow rate air supply method. Compared to open systems, semi-closed diving respirators conserve gas and provide longer underwater working time. The basic working principle of a constant-flow nitrogen-oxygen semi-closed diving respirator is as follows: a pre-mixed gas mixture (fresh gas) with a certain oxygen concentration is supplied to the breathing bag at a pre-set flow rate. After the fresh gas mixes with the gas in the breathing bag, it is supplied to the diver for breathing. The gas exhaled by the diver is absorbed and purified by the absorbent tank and then returned to the breathing bag. Excess gas is discharged from the breathing bag at the same rate as the fresh gas supply. Based on the working principle of this type of respirator, under steady conditions, the oxygen concentration (volume fraction) in its breathing circuit can usually be calculated using equation (1):

[0003]

[0004] This type of respirator has the following drawbacks: 1. As shown in equation (1), the oxygen concentration in the breathing circuit of this type of semi-closed respirator is related to the oxygen consumption (the air supply flow rate of the respirator and the oxygen concentration of the gas source are determined), while the oxygen consumption is related to the diver's workload underwater. Since the diver's underwater workload is not a constant value, the oxygen concentration in the breathing circuit of this type of respirator is an uncertain dynamic process during diving. To ensure decompression safety, it is necessary to use the oxygen partial pressure under the maximum workload to calculate the decompression scheme, which leads to an increase in decompression time, and the decompression scheme also requires a large number of experiments to verify its safety. 2. According to equation (1), when the diver's workload is high, this type of respirator needs to increase the air supply flow rate by designing a larger metering orifice to ensure that the diver does not lack oxygen, thus wasting a lot of gas. 3. This type of respirator relies entirely on the metering orifice to supply oxygen in a quantitative manner to ensure that the breathing gas is within a safe range. However, when the metering orifice malfunctions (blocked or partially blocked), there will be a risk of oxygen deficiency. Summary of the Invention

[0005] This invention addresses the problems and shortcomings of existing technologies by providing a novel variable-flow semi-closed recirculating diving respirator and its breathing method.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] This invention provides a variable flow semi-closed recirculating diving breathing apparatus, which includes an exhalation bag, an inhalation bag, a human breathing system, an absorbent canister, and a nitrogen-oxygen mixture cylinder. The breathing circuit is formed by the human breathing system, the exhalation bag, the absorbent canister, the inhalation bag, and the human breathing system connected in sequence. The invention is characterized by further including an oxygen partial pressure sensor connected to the exhalation bag, a constant flow valve and an electronic control valve connected in parallel between the inhalation bag and the nitrogen-oxygen mixture cylinder, and a control unit electrically connected between the oxygen partial pressure sensor and the electronic control valve.

[0008] The control unit has a pre-stored oxygen concentration setting value, which is greater than the oxygen concentration in the air, and the oxygen concentration setting value = target maximum oxygen partial pressure value / (0.1 * maximum working depth + 1). The oxygen concentration of the nitrogen-oxygen mixture in the nitrogen-oxygen mixture cylinder is higher than the oxygen concentration setting value.

[0009] The constant flow valve remains open while the diver is wearing a semi-closed recirculating breathing apparatus to supply the minimum flow rate of air corresponding to the maximum working depth.

[0010] The oxygen partial pressure sensor is used to detect the oxygen partial pressure of the breathing circuit in real time and transmit it to the control unit. The control unit is used to calculate the oxygen concentration based on the oxygen partial pressure, compare the oxygen concentration with the oxygen concentration set value, and control the electronic control valve to open when the oxygen concentration is lower than the oxygen concentration set value. The breathing circuit uses a nitrogen-oxygen mixed gas cylinder to supplement the nitrogen-oxygen mixed gas until the oxygen concentration increases to the oxygen concentration set value before controlling the electronic control valve to close.

[0011] The present invention also provides a breathing method for a variable flow semi-closed recirculating diving respirator, characterized in that it includes the following steps:

[0012] S1. The control unit stores an oxygen concentration setting value, which is greater than the oxygen concentration in the air, and the oxygen concentration setting value = target maximum oxygen partial pressure value / (0.1 * maximum working depth + 1). The oxygen concentration of the nitrogen-oxygen mixture in the nitrogen-oxygen mixture cylinder is higher than the oxygen concentration setting value.

[0013] S2. While the diver is wearing the semi-closed recirculating breathing apparatus, the constant flow valve is always open to supply air at the minimum flow rate corresponding to the maximum working depth.

[0014] S3. The oxygen partial pressure sensor detects the oxygen partial pressure of the breathing circuit in real time and transmits it to the control unit. The control unit calculates the oxygen concentration based on the oxygen partial pressure, compares the oxygen concentration with the oxygen concentration set value, and controls the electronic control valve to open when the oxygen concentration is lower than the oxygen concentration set value. The breathing circuit uses a nitrogen-oxygen mixed gas cylinder to supplement the nitrogen-oxygen mixed gas until the oxygen concentration increases to the oxygen concentration set value before controlling the electronic control valve to close.

[0015] The positive and progressive effects of this invention are as follows:

[0016] This invention designs a novel variable flow semi-closed recirculating diving respirator. This respirator can change the air supply flow according to the changes in the diver's workload, so as to maintain the oxygen concentration in the breathing circuit at the set oxygen concentration value.

[0017] In this invention, since the oxygen concentration in the breathing circuit is constant, the oxygen partial pressure in the breathing circuit can be controlled within a safe range (e.g., if the oxygen partial pressure is controlled to a maximum of 1.4 ata, then when diving to a maximum depth of 40m, the oxygen concentration setting can be set to 28%, and the oxygen concentration of the nitrogen-oxygen mixture can be set to 31% or more).

[0018] In this invention, the oxygen concentration setting (e.g., 28%) is typically set higher than the oxygen concentration of air (21%). Based on this, the theory of equivalent air diving depth for nitrogen-oxygen diving can be directly applied, and decompression can be performed directly according to the air diving decompression table at the equivalent air diving depth. No additional decompression plan is needed. Furthermore, because the oxygen concentration is higher than air, the non-decompression diving time can be extended, and the decompression time shortened. For example, if the oxygen concentration setting is 28% and the maximum depth is 40m, the equivalent air diving depth is 35.6m. Therefore, the 36m decompression plan in the air diving decompression table can be used, which not only extends the non-decompression dwell time but also shortens the decompression time. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a variable flow semi-closed recirculating diving respirator according to a preferred embodiment of the present invention.

[0020] Figure 2 A flowchart illustrating the breathing method of a variable flow semi-closed recirculating diving respirator according to a preferred embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figure 1 As shown, this embodiment of the invention provides a variable flow semi-closed recirculating diving breathing apparatus, which includes an exhalation bag, an inhalation bag, a human breathing system, an absorbent canister, and a nitrogen-oxygen mixture cylinder. The breathing circuit is formed by the human breathing system, exhalation bag, absorbent canister, inhalation bag, and human breathing system connected in sequence (human breathing system → exhalation bag → absorbent canister → inhalation bag → human breathing system). It also includes an oxygen partial pressure sensor connected to the exhalation bag, a constant flow valve and an electronic control valve connected in parallel between the inhalation bag and the nitrogen-oxygen mixture cylinder, and a control unit electrically connected between the oxygen partial pressure sensor and the electronic control valve.

[0023] The control unit has a pre-stored oxygen concentration setting value. This oxygen concentration setting value is greater than the oxygen concentration in the air, and the oxygen concentration setting value = target maximum oxygen partial pressure value / (0.1 * maximum working depth + 1). The oxygen concentration of the nitrogen-oxygen mixture in the nitrogen-oxygen mixture cylinder is higher than the oxygen concentration setting value.

[0024] The constant flow valve remains open while the diver is wearing a semi-closed recirculating breathing apparatus to supply the minimum flow rate corresponding to the maximum working depth.

[0025] The oxygen partial pressure sensor is used to detect the oxygen partial pressure in the breathing circuit in real time and transmit it to the control unit. The control unit is used to calculate the oxygen concentration based on the oxygen partial pressure, compare the oxygen concentration with the oxygen concentration set value, and control the electronic control valve to open when the oxygen concentration is lower than the oxygen concentration set value. The breathing circuit uses a nitrogen-oxygen mixture cylinder to supplement the nitrogen-oxygen mixture until the oxygen concentration increases to the oxygen concentration set value before controlling the electronic control valve to close.

[0026] In this embodiment, the design depth is 40m, and the constant flow valve is always open to ensure that the respirator always maintains a minimum air supply of 5L / min (this flow rate value can be determined according to the actual situation).

[0027] In this embodiment, an oxygen partial pressure sensor is used to measure the oxygen partial pressure in the breathing circuit in real time and convert it into oxygen concentration. When the oxygen concentration drops below the set oxygen concentration value, the electronic control valve opens to replenish the nitrogen-oxygen mixture until the oxygen concentration increases to the set oxygen concentration value, and then the electronic control valve closes.

[0028] In this embodiment, when setting the oxygen concentration setting value, in order to shorten the decompression time, the oxygen concentration setting value is usually set to be higher than the oxygen concentration of air. The oxygen concentration of the gas source (i.e., the oxygen concentration of the nitrogen-oxygen mixture) can be configured as needed, but it needs to be higher than the oxygen concentration setting value.

[0029] The advantage of this respirator in this embodiment is that, since the oxygen concentration in the breathing circuit is constant, the oxygen partial pressure in the breathing circuit can be controlled within a safe range (e.g., if the oxygen partial pressure is controlled to a maximum of 1.4 ata, then when diving to a maximum depth of 40m, the oxygen concentration setting can be set to 28%, and the oxygen concentration of the nitrogen-oxygen mixture can be set to 31% or more).

[0030] In this embodiment, the oxygen concentration setting (e.g., 28%) is typically set higher than the oxygen concentration of air (21%). Therefore, the theory of equivalent air diving depth for nitrogen-oxygen diving can be directly applied, and decompression can be performed directly according to the air diving decompression table at the equivalent air diving depth. No additional decompression plan is needed. Furthermore, because the oxygen concentration is higher than air, the non-decompression diving time can be extended, and the decompression time shortened. For example, if the oxygen concentration setting is 28% and the maximum depth is 40m, the equivalent air diving depth is 35.6m. Therefore, the 36m decompression plan in the air diving decompression table can be used, which not only extends the non-decompression dwell time but also shortens the decompression time.

[0031] The respirator in this embodiment uses a constant oxygen concentration, the gas supply flow rate varies according to the workload, and it supplies a nitrogen-oxygen mixture. Therefore, the gas is still periodically discharged from the respirator, so it is still defined as a semi-closed respirator.

[0032] like Figure 2As shown, this embodiment of the invention also provides a breathing method for a variable flow semi-closed recirculating diving respirator, which includes the following steps:

[0033] Step 101: The control unit stores the oxygen concentration setting value. This oxygen concentration setting value is greater than the oxygen concentration in the air, and the oxygen concentration setting value = target maximum oxygen partial pressure value / (0.1 * maximum working depth + 1). The oxygen concentration of the nitrogen-oxygen mixture in the nitrogen-oxygen mixture cylinder is higher than the oxygen concentration setting value.

[0034] Step 102: While the diver is wearing the semi-closed recirculating breathing apparatus, the constant flow valve remains open to supply air at the minimum flow rate corresponding to the maximum working depth.

[0035] Step 103: The oxygen partial pressure sensor detects the oxygen partial pressure of the breathing circuit in real time and transmits it to the control unit. The control unit calculates the oxygen concentration based on the oxygen partial pressure, compares the oxygen concentration with the oxygen concentration set value, and controls the electronic control valve to open when the oxygen concentration is lower than the oxygen concentration set value. The breathing circuit uses a nitrogen-oxygen mixed gas cylinder to supplement the nitrogen-oxygen mixed gas until the oxygen concentration increases to the oxygen concentration set value before controlling the electronic control valve to close.

[0036] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and all such changes and modifications shall fall within the scope of protection of the present invention.

Claims

1. A variable flow semi-closed recirculating breathing apparatus, comprising an exhalation bag, an inhalation bag, a human breathing system, an absorbent canister, and a nitrogen-oxygen mixture cylinder, wherein the human breathing system, exhalation bag, absorbent canister, inhalation bag, and human breathing system are sequentially connected to form a breathing circuit, characterized in that, It also includes an oxygen partial pressure sensor connected to the exhalation bag, a constant flow valve and an electronic control valve connected in parallel between the inhalation bag and the nitrogen-oxygen mixture cylinder, and a control unit electrically connected between the oxygen partial pressure sensor and the electronic control valve. The control unit has a preset oxygen concentration setting value, which is greater than the oxygen concentration in the air, and the oxygen concentration setting value = target maximum oxygen partial pressure value / (0.1 * maximum working depth + 1). The oxygen concentration of the nitrogen-oxygen mixture in the nitrogen-oxygen mixture cylinder is higher than the oxygen concentration setting value. The constant flow valve remains open while the diver is wearing a semi-closed recirculating breathing apparatus to supply the minimum flow rate of air corresponding to the maximum working depth. The oxygen partial pressure sensor is used to detect the oxygen partial pressure of the breathing circuit in real time and transmit it to the control unit. The control unit is used to calculate the oxygen concentration based on the oxygen partial pressure, compare the oxygen concentration with the oxygen concentration set value, and control the electronic control valve to open when the oxygen concentration is lower than the oxygen concentration set value. The breathing circuit uses a nitrogen-oxygen mixed gas cylinder to supplement the nitrogen-oxygen mixed gas until the oxygen concentration increases to the oxygen concentration set value before controlling the electronic control valve to close.

2. A breathing method for a variable flow semi-closed recirculating diving respirator, characterized in that, It utilizes the variable flow semi-closed recirculating breathing apparatus as described in claim 1, and the breathing method includes the following steps: S1. The control unit stores an oxygen concentration setting value, which is greater than the oxygen concentration in the air, and the oxygen concentration setting value = target maximum oxygen partial pressure value / (0.1 * maximum working depth + 1). The oxygen concentration of the nitrogen-oxygen mixture in the nitrogen-oxygen mixture cylinder is higher than the oxygen concentration setting value. S2. While the diver is wearing the semi-closed recirculating breathing apparatus, the constant flow valve is always open to supply air at the minimum flow rate corresponding to the maximum working depth. S3. The oxygen partial pressure sensor detects the oxygen partial pressure of the breathing circuit in real time and transmits it to the control unit. The control unit calculates the oxygen concentration based on the oxygen partial pressure, compares the oxygen concentration with the oxygen concentration set value, and controls the electronic control valve to open when the oxygen concentration is lower than the oxygen concentration set value. The breathing circuit uses a nitrogen-oxygen mixed gas cylinder to supplement the nitrogen-oxygen mixed gas until the oxygen concentration increases to the oxygen concentration set value before controlling the electronic control valve to close.

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